Aloe Vera & Glucosamine Joint Formula by Lifeplan Products Limited

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Each tablet contains: Glucosamine Sulphate 560 mg • Chondroitin Sulphate 150 mg • Calcium 75 mg • Vitamin C 50 mg • Aloe Vera (equivalent to 10 mL/10,000 mg fresh juice) 50 mg • Selenium 50 mcg.

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Below is general information about the effectiveness of the known ingredients contained in the product Aloe Vera & Glucosamine Joint Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe Vera)

POSSIBLY EFFECTIVE

Acne. Topical aloe gel may reduce acne lesions when used with topical tretinoin in children and adults with acne. Details: One clinical trial in children and adults with acne shows that topical application of a gel containing aloe 50% in the morning and evening, in addition to topical application of tretinoin 0.025% cream and twice daily cleansing with a medical soap, improves acne lesions by approximately 35% more than using the same treatments without aloe (90124).
Burns. Topical aloe gel or cream may reduce healing time in patients with superficial or partial thickness burns. Details: A meta-analysis of four small clinical trials in patients with second-degree burns shows that use of topical aloe vera reduces time to healing by about 4.4 days when compared to control groups treated with silvadene, silver sulfadiazine, or gauze containing 0.5% chlorhexidine acetate (110209). Most clinical research shows that applying aloe gel or cream topically up to twice daily reduces healing time when compared with silver sulfadiazine (19771,110210,110212), framycetin (19775), vaseline gauze (19773), or placebo (101,97320) in patients with superficial or partial thickness burns. Topical application of aloe cream up to twice daily might also decrease wound size when compared with silver sulfadiazine and framycetin (19771,19775). In addition, some clinical research in patients with burns caused by sulfur mustard shows that applying cream containing aloe and olive oil twice daily for 6 weeks improves pruritus similarly to betamethasone 0.1% cream and may lead to further reductions in excoriation and fissure (19768). However, some preliminary clinical research shows that applying fresh aloe mucilage or aloe extract daily is no more effective than silver sulfadiazine for reducing wound healing time in patients with superficial or partial thickness burns (19774,19776).
Constipation. Oral aloe latex may improve symptoms in patients with constipation; however, the U.S. Food and Drug Administration (FDA) has banned the use of aloe latex as a laxative due to safety concerns. Details: Taking aloe latex 100-200 mg daily or aloe extract 50 mg as a stimulant laxative seems to relieve constipation due to the cathartic effects of the anthraquinones in the aloe (4,5,8). Taking 1-3 capsules of a formulation containing aloe 150 mg, celandine 300 mg, and psyllium 50 mg also seems to improve stool consistency and the mean number of stools in patients with chronic constipation when compared with placebo (19747). However, in 2002, the U.S. FDA banned the use of aloe latex for constipation due to safety concerns (8229,8443).
Diabetes. Oral aloe may reduce blood glucose and glycated hemoglobin (HbA1c) in patients with diabetes. It may be most effective in patients with fasting blood glucose levels of 200 mg/dL or greater. Details: Most clinical research in adults with prediabetes and diabetes shows that taking aloe vera orally can reduce fasting blood glucose by 30-47 mg/dL and HbA1c by 0.41% to 1% (12164,17488,17489,19756,95943,95945,95946). One meta-analysis of 92 patients shows that aloe vera is associated with a larger overall reduction of fasting blood glucose in those with a baseline fasting blood glucose level greater than or equal to 200 mg/dL (95945). Another meta-analysis of 206 patients shows that aloe vera increases high-density lipoprotein (HDL) levels and reduces triglyceride, total cholesterol, and low-density lipoprotein (LDL) levels when compared with placebo in adults with prediabetes and untreated diabetes (95943). These analyses include studies that used multiple forms of aloe vera, including gel powder, extract, raw crushed leaves, and fresh extracted juice, as well as multiple doses ranging from 100-1000 mg of powder and 15-150 mL of juice taken for durations ranging from 4-14 weeks. Significant heterogeneity between studies, small sample sizes, and wide variability in the form and dose of aloe used limit the validity of these findings and the ability to identify an effective dose (95943,95945,95946). Additionally, some research has shown no benefit. This may be due to the different forms and doses of aloe used. One clinical study shows that taking aloe gel as 15 mL twice daily or taking aloe juice 15 mL twice daily does not decrease glucose levels in patients with type 2 diabetes (17420). Other clinical research shows that taking a specific aloe gel complex (Aloe QDM complex, Univera Inc.) containing processed aloe gel 147 mg twice daily for 8 weeks does not affect glycemic indices when compared with placebo in patients with diabetes or prediabetes (90121).
Genital herpes. Topical aloe extract cream may improve healing of genital herpes lesions. Details: Clinical research in males with genital herpes shows that applying a cream containing aloe extract 0.5% three times daily, 5 days weekly, for up to 2 weeks increases healing rates when compared with aloe gel or placebo. The mean time to healing after application of the aloe extract was 5 days, compared with 12 days with placebo (12164,19745,19746).
Lichen planus. Rinsing the mouth with aloe-containing mouthwash or applying aloe gel to the mouth or vulva may reduce pain and improve lesion healing in patients with lichen planus. Details: Clinical research in patients with oral lichen planus shows that using 0.4 mL of mouthwash containing aloe gel 70% three times daily for 12 weeks or applying a gel containing aloe mucilage 70% twice daily for 8 weeks is up to 6 times more likely to reduce pain when compared with placebo (19762,19763,19764). However, these findings are questionable due to poor study design. Other clinical research in patients with oral lichen planus shows that using 2 tablespoons of aloe-containing mouthwash four times daily for a month, or applying aloe gel three times daily for 8 weeks, reduces pain and improves lesion healing at least as much as triamcinolone acetonide paste (0.1% in one study) (19765,90130). However, aloe gel may not be as beneficial as laser therapy. A clinical study in patients with lichen planus show that applying a gel containing aloe powder 500 mg to the affected site three times daily for 2 months is less effective for improving pain and lesion healing than receiving low-level laser therapy twice weekly for 2 months. However, no between-group differences were maintained at 7 months after treatment completion (108722). A network meta-analysis of 2 small clinical trials shows that applying aloe trails only purslane of the herbal agents studied with regard to clinical improvement as measured by the Thongprasom scale. However, aloe does not seem to improve complete clinical resolution, clinical scores, or pain (111640). In patients with vulval lichen planus, clinical research shows that topical application with aloe gel twice daily for 8 weeks increases the number of patients who experience clinical improvement of at least 50% when compared with placebo (19766).
Obesity. Oral aloe gel may modestly reduce body weight and fat mass in adults who are overweight or obese. Details: One clinical trial in overweight and obese adults with diabetes or prediabetes shows that taking a specific aloe gel complex (Aloe QDM complex, Univera Inc.) containing processed aloe gel 147 mg twice daily for 8 weeks reduces body weight by 0.6 kg and fat mass by 1 kg when compared with placebo (90121).
Oral submucous fibrosis. Topical aloe may reduce burning sensations in patients with oral submucous fibrosis, but it may not improve mouth opening, tongue protrusion, or cheek flexibility in these patients. Details: A meta-analysis of five small clinical studies in patients with oral submucous fibrosis shows that topical application of aloe gel for 3 months reduces burning sensation, possibly for up to two months after treatment, when compared with placebo or active control. A network meta-analysis also found that aloe is most effective in reducing burning sensation, ranked only after treatment with corticosteroids, hyaluronidase, and antioxidants (113514). However, aloe does not seem to improve mouth opening, tongue protrusion, or cheek flexibility (100256). One of the studies included in the analysis used a specific aloe gel (Sheetal lab Surat) 5 mg applied topically on each side of the buccal mucosa three times daily for 3 months (90131). All of the studies included in the analysis were conducted in India, so it is unclear if the results are generalizable to other geographic locations. Limited research has also evaluated the use of topical and oral aloe vera in combination. A small clinical study shows that consuming pure aloe vera juice (Hamant Sai, Sun Vision Company) 30 mL twice daily and applying pure aloe vera gel (Hamant Sai, Sun Vision Company) three times daily for 3 months improves cheek flexibility and tongue protrusion when compared with a treatment regimen consisting of intralesional injections of hydrocortisone acetate 25 mg and hyaluronidase 1500 IU weekly for 6 weeks and supplementation with Cap SM Fibro (Indoco Remedies) twice daily for 3 months. Both treatment regimens show an improvement in mouth opening and burning sensation when compared to baseline, with the aloe vera treatment producing a more rapid improvement in burning sensation (95944). It is not clear how this combination of oral and topical aloe vera compares with topical aloe vera alone.
Psoriasis. Topical aloe extract cream may reduce erythema and scaling and improve the resolution of psoriatic plaques in patients with psoriasis. Limited research suggests that topical aloe gel does not have the same effects. Details: Applying aloe extract 0.5% cream topically three times daily for 4 weeks significantly improves and increases the resolution of psoriatic plaques when compared with placebo (101,12096,12164). Aloe extract cream also seems to reduce desquamation, erythema, and infiltration (12096). Other preliminary clinical research shows that applying cream containing aloe mucilage 70% twice daily for 8 weeks improves psoriasis severity more effectively than triamcinolone 0.1% cream, although both treatments had similar effects on dermatology-specific quality of life (19741). Treatment with aloe gel does not seem to improve erythema, infiltration, and desquamation associated with psoriasis when compared with placebo (19748).
Traumatic oral ulcers. Topical aloe gel may prevent oral ulcers after application of orthodontic appliances in adolescents and adults. Details: Clinical research in patients aged 12 years and older shows that applying a gel containing aloe 80% to the gums twice daily for one month after the cementation of orthodontic appliances prevents the development of mouth ulcers when compared with a chlorhexidine gel. Ulcers occurred in about 6% of patients using the aloe gel compared with 81% of those using the chlorhexidine gel. Bleeding and inflammation were also reduced (103305).

INSUFFICIENT RELIABLE EVIDENCE to RATE

Alveolar osteitis. It is unclear if topical aloe or the aloe constituent acemannan is beneficial in patients with alveolar osteitis. Details: One small clinical trial in patients with alveolar osteitis shows that applying a patch containing the aloe constituent acemannan (SaliCept patch) to the tooth socket, once after curettage and irrigation and again 3 days later, reduces pain intensity and improves clinical symptoms when compared with curettage and irrigation alone (19754).
Amenorrhea. Although there has been interest in using oral aloe for amenorrhea, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Anal fissures. It is unclear if topical aloe is beneficial in patients with anal fissures. Details: One small clinical study in patients with chronic anal fissures shows that applying an aloe cream containing 0.5% powdered spray-dried inner aloe leaf juice (Zarban Phyto-Pharmaceutical Co) three times daily for at least 3 weeks, as an adjuvant to sitz baths three times daily, using a laxative, and eating a full fiber diet, improves pain, wound healing, and bleeding severity when compared with placebo (90129).
Asthma. Although there has been interest in using oral aloe for asthma, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Atopic dermatitis (eczema). Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in patients with atopic dermatitis shows that application of a specific combination cream (Olivederma, Kimi Daru Pharmaceutical Co.) containing aloe gel and virgin olive oil twice daily for 6 weeks improves disease severity and quality of life when compared with betamethasone cream (105020). It is unclear if this effect is due to aloe, olive oil, or the combination.
Breast engorgement. It is unclear if topical aloe improves lactation-associated breast pain. Details: Meta-analyses of 4-5 clinical trials in lactating patients show that use of topical aloe modestly reduces nipple/breast pain and irritation when compared with no treatment, routine care with topical breast milk or breast massage, or treatment with lanolin (110213). However, studies included in this analysis were not specific to breast engorgement.
Burning mouth syndrome. It is unclear if topical aloe is beneficial in patients with burning mouth syndrome. Details: One small clinical trial in patients with chronic burning mouth syndrome shows that applying 0.5 mL of aloe 70% gel to sore areas on the tongue three times daily prior to wearing a tongue protector for 12 weeks does not improve pain or symptoms when compared with placebo gel or using the tongue protector alone in patients with chronic burning mouth syndrome (90127). However, differences in baseline pain ratings between study groups limit the validity of these findings.
Cancer. Oral aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study in patients with lung cancer shows that, when administered with standard chemotherapy, three daily doses of 10 mL of a mixture consisting of fresh aloe leaves 300 grams plus honey 500 grams dissolved in 40 mL of alcohol 40% increases the rate of complete response, partial response, or disease control when compared with chemotherapy alone (19752).
Canker sores. Small clinical studies suggest that applying the aloe constituent acemannan to cancer sores may reduce ulcer size, but not pain. However, the effect of aloe is unclear. Details: Meta-analyses of clinical research show that topical aloe is no more effective than control interventions for reducing the size and pain of oral ulcers (110216). Control interventions have included carrier gel or triamcinolone acetonide 0.1% (19751,110216). However, a recent clinical trial shows that topical aloe gel (G.U.M Canker-X, Sunstar Americas, Schaumburg, USA) after meals and before bedtime for 5 days is more effective than amlexanox 5% paste and placebo for reducing pain and the size of canker sores in patients with recurrent symptoms (110215). Other small clinical trials have investigated the effects of fermented aloe or the aloe constituent acemannan. One small clinical trial in adults with recurrent canker sores shows that applying a fermented aloe gel to oral ulcers three times daily seems to accelerate healing time when compared with chitosan gel (104173). Another small clinical trial in patients with canker sores shows that using a wound dressing containing the aloe constituent acemannan (Carrisyn Gel Wound Dressing) shortens the average healing time of canker sores when compared with an oral analgesic (Orabase-Plain) (19750). Other clinical research shows that applying acemannan 0.5% in Carbopol 934P NF three times daily for 7 days reduces ulcer size, but not pain, when compared with Carbopol 934P NF alone in patients with canker sores (90123). However, applying triamcinolone acetonide 0.1% appears to be more effective in reducing pain and similarly effective in reducing ulcer size when compared with acemannan 0.5% (90123).
Common cold. Although there has been interest in using oral aloe for the common cold, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Dental plaque. Using aloe-containing toothpaste may reduce dental plaque in adults; however, it is unclear if this is more effective than fluoride-containing toothpaste. Rinsing with an aloe-containing mouthwash may reduce dental plaque in children. Details: One small clinical trial in adults shows that brushing teeth with a dentifrice containing aloe gel (Forever Bright, Forever Living Products) three times daily for 30 days does not reduce the occurrence of plaque better than a fluoridated dentifrice (Sorriso Dentes Brancos, Kolynos do Brasil), although both treatments seem to show improvement when compared to baseline (19755). Another small clinical study in adults with gingivitis shows that using toothpaste containing aloe daily for 24 weeks reduces plaque more effectively than placebo or triclosan-containing toothpaste (19760). In children aged 8-14 years with mild plaque, using a mouth wash containing aloe vera 7% twice daily for 4 weeks reduced plaque by a large amount when compared with placebo. In addition, it was as effective as chlorhexidine 0.2% (103306).
Depression. Although there has been interest in using oral aloe for depression, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Diabetic foot ulcers. It is unclear whether topical aloe is beneficial for patients with diabetic foot ulcers. Details: One small clinical trial in patients with a stage 1 or 2 diabetic foot ulcer who are receiving oral antibiotics shows that applying a topical product containing aloe and great plantain twice daily for 4 weeks reduces ulcer surface area and time to healing, but not ulcer depth, when compared with antibiotics alone (97323). The effect of applying aloe gel alone without concomitant oral antibiotic therapy is unknown.
Diaper rash. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial shows that applying a cream containing aloe gel and olive oil three times daily for 5-10 days reduces diaper rash severity in children less than 3 years of age when compared to baseline; however, it does not seem to be as effective as calendula ointment (19779). The validity of this finding is limited by the lack of a placebo group.
Dry mouth. It is unclear if rinsing with an aloe-containing mouthwash is beneficial for dry mouth. Details: In patients with dry mouth related to type 2 diabetes, clinical research shows that an aloe vera 50% mouthwash, as 20 mL swished and spit three times daily for 14 days, modestly reduces symptoms of dry mouth when compared with rinsing with a saline control mouthwash (106068). The validity of this study is limited due to unclear reporting.
Dry skin. Topical aloe or oral aloe sterols may improve some measures of dry skin. However, findings are mixed due to the use of varied formulations and doses. Details: One small clinical trial shows that applying a cream containing freeze-dried aloe extract 0.1% to 0.5% to the skin for 2 weeks increases the amount of water in the stratum corneum, but does not reduce transepidermal water loss, when compared with placebo (19758). Another small clinical study in females with occupational dry skin shows that wearing gloves coated in aloe 8 hours daily for 30 days improves symptoms of dry skin when compared with no treatment (19759). However, it is not clear if the benefits resulted from applying aloe or wearing gloves. One small clinical trial in healthy females shows that consumption of a yogurt containing 500 mg of aloe vera gel powder (0.4 mg of aloe sterol) daily for 12 weeks increases skin hydration, skin elasticity, and collagen content of the dermis while reducing markers of skin fatigue and transepidermal water loss when compared with placebo (95942). However, another study in healthy females shows that taking aloe sterol-enriched aloe extract 0.5 grams daily for 12 weeks does not improve skin hydration when compared with placebo, although redness, itching, collagen content, and transepidermal water loss were improved (101577).
Epilepsy. Although there has been interest in using oral aloe for epilepsy, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Frostbite. Although there has been interest in using topical aloe for frostbite, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Gingivitis. Using aloe-containing toothpaste may reduce gingivitis in adults, but it does not seem to be more effective than fluoride-containing toothpaste. Rinsing with an aloe-containing mouthwash may reduce gingivitis in children. Details: One small clinical trial in adults shows that brushing teeth with a dentifrice containing aloe gel (Forever Bright, Forever Living Products) three times daily for 30 days does not reduce the occurrence of gingivitis more effectively than a fluoridated dentifrice (Sorriso Dentes Brancos, Kolynos do Brasil), although both treatments seem to show improvement when compared to baseline (19755). Another small clinical study in adults with gingivitis shows that using aloe-containing toothpaste daily for 24 weeks reduces gingivitis more effectively than placebo, but not more than triclosan-containing toothpaste (19760). In children aged 8-14 years with mild gingivitis, using a mouthwash containing aloe vera 7% twice daily for 4 weeks reduced gingivitis by a large amount when compared with placebo. In addition, it was as effective as chlorhexidine 0.2% (103306).
Heart failure. It is unclear if oral aloe is beneficial in patients with systolic heart failure. Details: A very small clinical study in adults with moderate to moderately severe chronic systolic heart failure shows that taking aloe vera gel capsules 150 mg twice daily for 8 weeks in addition to standard treatment decreases New York Heart Association (NYHA) functional class, improves Minnesota Living with Heart Failure Questionnaire (MLHFQ) total, physical, emotional, and social scores, and enhances sleep quality but does not reduce the severity of obstructive sleep apnea scores or improve six-minute walk test distance when compared with placebo (111663). The study may have been inadequately powered to detect a difference between groups. Additionally, the validity of these effects may be limited by the small sample size.
Hematopoietic stem cell transplant (HSCT). Oral and topical aloe have only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients undergoing hematopoietic stem cell transplantation shows that treatment with colostrum and aloe orally (Remargin Colostrum Gastro-Gel, Solimè srl, Cavriago, Reggio Emilia, Italy) and as a mouthwash (Remargin Colostrum OS, Solimè srl, Cavriago, Reggio Emilia, Italy) modestly reduces the risk and duration of severe oral mucositis and febrile neutropenia when compared with historical values. There was no effect on the duration of neutropenia, the length of hospital stay, pain, or duration of medications. All patients were also given standard care. The mouthwash was used after each oral hygiene, and the oral treatment was 3 to 5 times daily depending on symptoms (110211).
Hepatitis. It is unclear if oral aloe is beneficial in patients with hepatitis. Details: One small clinical trial in patients with liver fibrosis primarily caused by hepatitis B or hepatitis C shows that taking a high molecular weight fraction of aloe 0.05 grams three times daily for 12 weeks reduces fibrosis, attenuates liver enzyme activity, and decreases hepatic glutathione content when compared with placebo (19780).
HIV/AIDS. Small clinical studies suggest that oral aloe or the aloe constituent acemannan may not improve CD4 counts or viral load in patients with HIV. Details: One small clinical trial in patients with HIV shows that taking the aloe constituent, acemannan, 400 mg four times daily does not significantly improve CD4 counts, ratio of CD4 to CD8, or viral load when compared with placebo (19851). Another small clinical study in patients with HIV shows that taking aloe gruel 30-40 mL daily does not improve CD4 counts when compared with those treated with antiretroviral therapy, although both groups show similar increases in weight compared to baseline (19852).
Hyperlipidemia. Although there has been interest in using oral aloe for hyperlipidemia, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Hypertrophic scars. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in patients undergoing median sternotomy shows that applying a silicone gel containing aloe extract and other herbal extracts (Bangkok Botanica) to postoperative hypertrophic scars for 6 months reduces the height of the scar and improves pliability by a moderate amount when compared with a silicone placebo gel. There was no effect on pigmentation or vascularity (102793). It is unknown whether any benefit is related to aloe, other ingredients, or their combination.
Influenza. Oral aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in healthy adults shows that taking a combination supplement containing aloe vera gel, rosemary, and poria mushrooms twice daily 28 days before administering the influenza vaccine and 28 days after vaccination does not improve immunologic markers or reduce symptom severity, symptom duration, frequency of upper respiratory tract infection symptoms, or the use of cold and flu medications when compared with placebo (111921).
Irritable bowel syndrome (IBS). Small clinical studies suggest that oral aloe extract or juice may not improve symptoms in patients with IBS. Details: Most research suggests that aloe is not effective for improving symptoms of IBS; however, the available evidence is of low-quality, with some studies having high dropout rates or inadequate power to detect significant differences. Two clinical trials show that taking a specific aloe extract (AVH200, Calmino Group AB) 250-500 mg twice daily for 4 weeks does not improve IBS-related symptoms or response rates when compared with placebo (101579,104169), although one of these studies did find a trend toward a higher response rate, defined as a 50% or greater improvement in symptom scores, with aloe over placebo (104169). Also, a pooled analysis of these two studies shows that taking this specific product improves IBS-related pain severity and frequency in patients with diarrhea-prominent IBS (IBS-D) when compared with placebo, but does not seem to improve stool consistency or frequency (108718). Clinical trials evaluating aloe juice 50 mL four times daily for 1 month or 60 mL twice daily for 5 months show no significant improvement in quality of life scores or IBS symptoms when compared with placebo (104170,104171), although one study did find a trend toward improved response in patients with IBS-D (104171). Despite a lack of significant findings in the individual studies, a pooled analysis of the two smallest studies above (104169,104171) shows that aloe extract or juice, taken for 4 weeks, may increase the rate of symptom response by almost 70% when compared with placebo (103307).
Nipple Fissures. It is unclear if application of an aloe poultice improves nipple-related complications of breastfeeding, such as nipple fissures. Details: A clinical study in females who have just given birth and are breastfeeding for the first time shows that applying a poultice containing aloe gel to the nipples after breastfeeding six times daily for 5 days improves nipple eschar when compared with no treatment. Although there were modest improvements in other outcomes, such as redness, fissures, and epidermolysis, these differences were not significant (108721). Participants were instructed to clean with purified water before the next breastfeeding session.
Multiple sclerosis (MS). Although there has been interest in using oral aloe for MS, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Oral mucositis. Small clinical studies suggest that oral aloe juice or application of aloe solution inside the mouth may prevent oral mucositis in patients receiving chemotherapy or radiation. Details: Some clinical research shows that drinking 15 mL of juice containing aloe 80% three times daily during radiation therapy decreases the risk of developing moderate or severe mucositis by approximately 39% when compared with placebo (19767,19964). In addition, in children aged 3-6 years undergoing chemotherapy for leukemia, application of a solution containing aloe 70% twice daily inside the mouth, starting three days before chemotherapy, reduces the severity of oral mucositis and delays its onset by 2 weeks when compared with sodium bicarbonate 5% (103304). Other clinical research in adults with head and neck cancer shows that rinsing and then swallowing 20 mL of a solution containing aloe juice 94.5% four times daily throughout the course of radiation therapy does not prevent mucositis when compared with placebo (19963). However, this study was not adequately powered to detect significant differences between study groups. Aloe has also been evaluated in combination with other ingredients for the treatment of oral mucositis. Preliminary clinical research in patients undergoing hematopoietic stem cell transplantation shows that treatment with colostrum and aloe orally (Remargin Colostrum Gastro-Gel, Solimè srl, Cavriago, Reggio Emilia, Italy) and as a mouthwash (Remargin Colostrum OS, Solimè srl, Cavriago, Reggio Emilia, Italy) modestly reduces the risk and duration of severe oral mucositis when compared with historical values. There was no effect on overall risk or time of onset of mucositis. All patients were also given standard care. The mouthwash was used after each oral hygiene, and the oral treatment was 3 to 5 times daily depending on symptoms (110211). Another small clinical study in adults with head and neck cancer receiving radiotherapy shows that rinsing with 5 mL of a mouthwash containing aloe, German chamomile, peppermint oil, and honey 3 times daily for 60 seconds for 6 weeks starting on the first day of radiotherapy reduces oral mucositis incidence, severity, and pain when compared with chlorhexidine and placebo (111291). It is unclear if these findings are due to aloe, other ingredients, or the combination.
Osteoarthritis. Although there has been interest in using oral and topical aloe for osteoarthritis, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Peptic ulcers. Although there has been interest in using oral aloe for peptic ulcers, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Periodontitis. It is unclear if application of aloe inside the mouth is beneficial for chronic periodontitis. Details: A meta-analysis of small clinical studies in patients with chronic periodontitis shows that using various aloe-containing gels, mouthwashes, and toothpastes improves plaque index when compared with placebo or other treatments (i.e., chlorhexidine rinse, metformin, and tea tree oil). The effect of these aloe products on gingival index could not be determined (108719). The validity of this finding is limited by the variety of aloe formulations and comparators used in the included studies.
Pressure ulcers. It is unclear if topical aloe is beneficial for the prevention or treatment of pressure ulcers. Details: One small clinical study shows that applying a gel containing the aloe constituent acemannan to pressure ulcers daily for 10 weeks does not reduce the time to healing when compared with management with moist saline gauze (12160,19853). Another small clinical study conducted in Iran in patients with category II pressure ulcers shows that applying topical aloe vera gel after cleaning with normal saline and prior to dressing daily for 15 days reduces pain during dressing changes when compared with normal saline dressing (113672). Other clinical research shows that cleansing wounds with a saline spray containing aloe, silver chloride, and decyl glucoside for 2 weeks improves pressure ulcer healing when compared with isotonic saline spray (19854). It is unclear if this improvement is due to aloe, other ingredients, or the combination in the spray. Aloe has also been evaluated for the prevention of pressure ulcers. A small clinical study in hospitalized patients in an orthopedic ward shows that applying aloe vera gel to the hips, sacrum, and heels twice daily for 10 days reduces pressure ulcer occurrence to 3 of 39 patients, compared to 12 of 38 patients of those receiving placebo (98816). However, methodological limitations with this study, including differences in how the gels were applied, limit the reliability of these results. A clinical study in hospitalized patients receiving intensive care has evaluated either aloe gel 94%, olive oil 100%, or a compounded product containing aloe vera and olive oil in a 3:2 ratio, applied to pressure areas as 10-15 mL every 8 hours. At the end of 30 days, pressure ulcers occurred in 17% of patients receiving the combination product, 20% receiving olive oil, 33% receiving aloe gel, and 37% receiving standard care, suggesting that any benefit may be due to olive oil (108723).
Radiation dermatitis. There is conflicting evidence about the effectiveness of topical aloe gel for preventing or delaying dermatitis in patients undergoing radiation therapy. These conflicting findings may be due to differences in study designs, products used, and application practices. Details: Two meta-analyses of clinical trials, some of which overlap, in patients with various types of cancer shows that topical aloe does not reduce the incidence or severity of radiation dermatitis (110325,113674) and does not reduce the incidence of erythema, pruritis, moist desquamation, or dry desquamation when compared with control (110325). However, the included studies are limited by a lack of blinding, questionable methodological quality, and a high risk of bias. In contrast, another meta-analysis of generally poor quality randomized controlled trials shows that topical pre-treatment application with aloe as gel, cream, lotion, or fresh plant reduces the risk of radiation dermatitis by 23%, especially mild to moderate radiation dermatitis, when compared with a control group not treated with aloe (110214). One U.S. study included in the analysis shows that applying aloe 98% gel twice daily starting within three days of radiation initiation does not reduce radiation dermatitis when compared with a placebo gel or no treatment (12163). Other research has focused on specific side effects. One clinical trial shows that applying aloe 98% gel three times daily throughout radiation treatment and after treatment does not seem to reduce symptoms of radiation dermatitis in patients being treated for breast cancer (12098). Some research shows that applying aloe 100% gel 6-8 times daily might prolong the time before radiation-related side effects occur, but only when the cumulative dose of radiation is high (>2,700 cGy) (12159). In addition, applying aloe-based gel once daily after radiation treatment is less effective than applying anionic phospholipid-based cream for reducing dryness, erythema, and peeling in children being treated for Hodgkin disease (19855). Aloe has also been evaluated in combination with other ingredients. A small cohort study in patients with head and neck cancer receiving radiation therapy shows that applying aloe 2% and radish 4% gel twice daily until ten days after the last radiotherapy session prevents radiation dermatitis as shown by fewer cases of radiation dermatitis in the 10th, 30th, and 35th radiation sessions when compared with placebo. Furthermore, after the 35th session, the subjects prophylactically treated with the aloe and radish gel had milder grades of radiation dermatitis when compared with control (111662). A preliminary clinical study shows that applying a specific cream product (Radioskin 2, Herbalab di Perazza Massimiliano Company), which contains aloe, ginkgo extract, and metal esculetina, along with another specific cream product (Radioskin 1, Herbalab di Perazza Massimiliano Company), which contains alga atlantica and ethylbisiminomethylguaicolo manganese cloruro, may improve skin hydration and reduce skin toxicity associated with radiation therapy in patients with breast cancer (89727). These creams were applied topically 2-3 times daily at least 3 hours before and after radiation treatment, from 15 days prior to radiation until one month after completion.
Radiation proctopathy. It is unclear if topical aloe is beneficial for the prevention or treatment of radiation proctopathy. Details: One very small clinical study in females with radiation proctopathy shows that applying 1 gram of an ointment containing aloe vera 3% rectally twice daily in conjunction with taking sulfasalazine 500 mg four times daily for 4 weeks modestly reduces diarrhea, fecal urgency, radiation toxicity, and clinical symptoms when compared with sulfasalazine alone (95941). This same product, applied twice daily for 6 weeks starting on the first day of radiotherapy, has also been evaluated for the prevention of radiation proctopathy. One small clinical study in patients with pelvic cancer shows that applying this ointment prevents proctopathy-related diarrhea, rectal bleeding, and fecal urgency when compared with placebo. Proctopathy-related symptoms occurred in 5% of patients using aloe, compared with 65% of those using placebo. However, there was no difference in rectal pain, constipation, or symptoms of cystitis between groups (101578). A very small clinical study in patients with colorectal cancer shows that applying this ointment prevents proctopathy-related diarrhea and reduces proctopathy severity, but does not improve rectal bleeding, rectal pain, fecal urgency, or symptoms of cystitis, when compared with placebo (108717). Reasons for discrepancies are unclear but might relate to differences in cancer diagnosis and radiation regimens.
Scabies. It is unclear if topical aloe is beneficial in patients with scabies. Details: One small open-label clinical study in children and adults with scabies shows that application of crude aloe gel for 3 consecutive days, repeated again after one week, may reduce itching and lesions similar to benzyl benzoate lotion in patients with scabies when compared to baseline (19769). The validity of this finding is limited by the lack of a placebo group.
Seborrheic dermatitis. It is unclear if topical aloe is beneficial in patients with seborrheic dermatitis. Details: One small clinical study in adults with seborrheic dermatitis shows that applying aloe 30% emulsion twice daily for 4-6 weeks reduces scaling, itching, and the number of sites involved, but not erythema, when compared with placebo (19749).
Stretch marks (striae gravidarum). It is unclear if topical aloe is effective for the prevention or treatment of stretch marks. Details: One small clinical trial in nulliparous patients shows that topical application of a cream containing aloe twice daily, starting at gestational week 16-18, reduces erythema and itching related to abdominal stretch marks, but does not seem to decrease the number of stretch marks, when compared with a base cream (97322). Aloe gel has also been evaluated in combination with fractional carbon dioxide (CO2) laser treatments. A small clinical trial shows that applying a gel containing aloe 87.4% twice daily for up to one month after each of three CO2 laser treatments improves the texture of the skin for up to 6 months after the last laser treatment when compared to baseline. This was as effective as topical recombinant human epidermal growth factor (rhEGF) and CO2 laser treatments. However, when specific sites were examined, only the texture of stretch marks on the buttocks were improved, and these improvements were less than those seen with rhEGF (101580). The effect of aloe for the prevention of stretch marks is unknown.
Sunburn. Although there has been interest in using topical aloe for sunburn, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Tungiasis. Topical aloe has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study shows that applying a product containing coconut oil, jojoba oil, and aloe leaf extract (Zanzarin, Engelhard Arzneimittel GmbH & Co. KG) to the feet twice daily for one-week intervals seems to reduce the number of embedded sandfleas in individuals with tungiasis when compared with a control group (19778). It is not clear if this effect is due to aloe, the other ingredients, or the combination.
Ulcerative colitis. It is unclear if oral aloe gel is beneficial in patients with ulcerative colitis. Details: One small clinical trial in patients with mild to moderate ulcerative colitis shows that taking aloe gel for 4 weeks, starting at 25-50 mL twice daily for the first 3 days and increasing to 100 mL twice daily thereafter, reduces symptoms when compared with placebo (11984).
Vaginitis. It is unclear if topical aloe is beneficial for vaginitis. Details: One small clinical trial in postmenopausal patients with atrophic vaginitis shows that applying 5 mg of a vaginal cream containing aloe gel 2% nightly for 2 weeks, then 3 nights per week for 4 weeks, reduces vaginal dryness, burning, and pain during intercourse and improves measures of vaginal health and maturity when compared to baseline. These effects were similar to those seen with estrogen vaginal cream (104175).
Varicose veins. Although there has been interest in using oral and topical aloe for varicose veins, there is insufficient reliable information about the clinical effects of aloe for this purpose.
Wound healing. There is conflicting evidence about the effectiveness of topical aloe products for improving wound healing. These conflicting findings may be due to differences in study designs, products used, and application practices. Details: One small clinical study shows that applying aloe gel to a caesarean wound after surgery, followed by a dry gauze, improves wound healing over the first 24 hours when compared with the dry gauze alone (90128). However, other clinical research in a small number of patients undergoing gynecologic surgery or cesarean section shows that applying an aloe gel extract (Carrington Dermal Wound Gel) to surgical wounds may actually delay wound healing (11982). Another small clinical trial shows that applying a formulation of aloe gel 0.5% cream (Zarband, Phytopharmaceutical Co.) to hemorrhoidectomy wounds three times daily for 4 weeks improves healing rates and pain relief scores and decreases intake of narcotic analgesics when compared with placebo (17418). However, another clinical trial in patients with biopsy wounds shows that application of a hydrogel containing the aloe constituent, acemannan (Carrasyn, Carrington hydrogel), does not improve wound epithelialization, wound infections, or pain when compared with conventional therapy (19856). Additionally, there is contradictory evidence about the effectiveness of aloe for improving skin graft donor site healing. One small clinical study shows that applying aloe gel 87.4% daily to split-thickness skin graft donor sites reduces time to complete healing by about 2 days when compared with placebo (97320). However, another small clinical study shows that applying aloe cream three times daily to split-thickness skin graft donor sites does not improve healing time when compared with placebo (97321).
Wrinkled skin. Although there has been interest in using topical aloe for wrinkled skin, there is insufficient reliable information about the clinical effects of aloe for this purpose. More evidence is needed to rate aloe for these uses.

(Read more about ALOE)

CALCIUM

EFFECTIVE

Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

POSSIBLY EFFECTIVE

Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
Hypertension. Oral calcium seems to reduce blood pressure by a small amount. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies show that intake of calcium supplements or dietary calcium modestly reduces blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as salt-sensitive people and patients with low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221). Also, a meta-analysis of clinical research shows that calcium intake during pregnancy reduces systolic blood pressure in offspring by 1-2 mmHg (38852). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplement sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367).
Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia in high risk pregnancies, especially if calcium intakes are low. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces pregnancy-related hypertension and pre-eclampsia (973,1833,8828,39043,39319,39426,96480). Calcium appears to reduce the risk of pre-eclampsia by about 50% when compared with placebo. One meta-analysis of 19 controlled trials involving over 29,000 pregnancies found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (96480). Calcium appears to have the greatest effect in individuals at high-risk of pre-eclampsia or with low calcium levels, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,96480,99714). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely. Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium supplementation 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low, in order to prevent pre-eclampsia (97347).
Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

POSSIBLY INEFFECTIVE

Breast cancer. Oral calcium does not seem to be beneficial for breast cancer prevention. Details: Although some population research disagrees (15631,39041,95811,107237), most research shows that increased calcium intake is not associated with a reduced risk of breast cancer (15631,16715,98895,107236,107237). Subgroup analyses of population research suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237). Another subgroup analysis in a large meta-analysis of population research also suggests that dietary intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most other research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: The most recent and robust meta-analysis of clinical research shows that calcium supplementation with or without vitamin D is NOT associated with reduced fractures in older adults without osteoporosis (95822). A large-scale study in postmenopausal females aged 50-79 years suggests calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the Women's Health Initiative study found that, in older females with the lowest genetic susceptibility to low bone mineral density (BMD), taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
Obesity. Oral calcium does not seem to improve weight loss. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). The most recent meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308).

INEFFECTIVE

Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

INSUFFICIENT RELIABLE EVIDENCE to RATE

Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
Diabetes. It is unclear if oral calcium is beneficial for type 2 diabetes prevention. Details: Some population research has found that a higher intake of calcium from diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473). However, population research is often limited by confounding variables. For example, one analysis found that any beneficial effect might be influenced by concomitant magnesium intake (96473). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis. This study is limited because it was not determined whether increased serum calcium was due to increased calcium intake or another factor such as parathyroid function (95815).
Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
Hypercholesterolemia. It is unclear if oral calcium is beneficial for hypercholesterolemia. Details: Some evidence shows that taking calcium carbonate 400 mg three times daily reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% after 6 weeks of treatment when used in combination with a low-fat diet (American Heart Association Step 1) (2557). In contrast, a study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years might INCREASE total cholesterol levels by about 12 mg/dL when compared with placebo. This same study showed an association between calcium supplementation and an increase in total cholesterol levels and carotid intimal thickness in postmenopausal females, but not premenopausal females (97350). A recent meta-analysis of randomized controlled trials which included both healthy patients and patients with dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is more effective in patients with dyslipidemia at baseline. It is unclear if this effect is due to calcium, vitamin D, or the combination (107227). However, other research shows that taking a specific supplement containing calcium 600 mg plus vitamin D 200 IU (Caltrate 600 D, Wyeth Consumer Healthcare Inc.) twice daily in combination with calorie restriction does not reduce total or LDL cholesterol levels when compared with placebo (15601).
Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

(Read more about CALCIUM)

CHONDROITIN SULFATE (Chondroitin Sulphate)

POSSIBLY EFFECTIVE

Cataracts. Chondroitin sulfate in combination with sodium hyaluronate is approved as a medical device to be ophthalmically injected during cataract surgery. It is unknown if other routes of administration are beneficial. Details: Injecting ophthalmic viscosurgical devices (OVDs) containing a combination of chondroitin sulfate and sodium hyaluronate into the eye protects the corneal endothelium during small-incision cataract surgery. Various medical devices containing chondroitin sulfate and sodium hyaluronate (Viscoat, Alcon Laboratories) have been granted approval by US Food and Drug Administration (FDA) for use as an adjunct to cataract surgery (89436,89437). However, OVDs that cannot be easily removed after surgery can cause intraocular pressure (IOP) spikes and reduced visual acuity. A meta-analysis of small clinical studies shows that using a specific chondroitin sulfate 4% and sodium hyaluronate 3% solution (Viscoat, Alcon Laboratories) after small-incision cataract surgery increases IOP at postoperative days 1 and 2, but not at any later postoperative days for up to 1 month (104452).
Osteoarthritis. Chondroitin sulfate seems to modestly reduce osteoarthritis pain and improve function. Pharmaceutical-grade chondroitin sulfate products have shown the most benefit. Details: Meta-analyses of randomized controlled trials in patients with mostly knee osteoarthritis show that taking chondroitin sulfate 800-2000 mg in single or divided doses daily for at least 3 months modestly reduces pain and disability when compared with placebo. However, included studies were heterogeneous and most had high attrition bias. A sub-group analysis of high-quality studies shows that 16 patients need to take chondroitin sulfate for 6 months for one patient to experience at least a 20% reduction in pain (94381,95792,99685,104446). When compared with conventional treatments like diclofenac 50 mg three times daily, chondroitin sulfate improves symptoms more slowly; however, the improvement seems to persist for up to 3 months after treatment cessation (322). Chondroitin also seems to have disease-modifying benefits. Clinical research in patients with osteoarthritis of the knee or hip shows that taking chondroitin sulfate 800 mg daily or more for 2 years might modestly reduce joint degeneration and narrowing when compared with placebo or celecoxib (42348,42398,94381,95516). Overall, most of the positive research involved pharmaceutical-grade chondroitin sulfate products, which are available as prescription products in some countries, such as Chondrosulf (IBSA Institut Biochimique SA) (17732,42348,42398,42536,89596,94360,104446), Chondrosan (Bioibérica, S.A.) (42463,42513), and Structum (Laboratoires Pierre Fabre) (22212,42520,89593). One clinical study shows that taking a pharmaceutical-grade chondroitin product (Chondrosulf) 800 mg daily seems to be comparable to taking celecoxib 200 mg daily for reducing pain and improving knee function (94360). Pharmaceutical-grade chondroitin products might demonstrate greater benefit due to higher quality (94360,102116). It is also important to note that most clinical studies using pharmaceutical-grade products are manufacturer-funded (94381). Furthermore, they may not be readily available for purchase in the US. Experts have conflicting stances on the use of chondroitin for osteoarthritis. The American College of Rheumatology (ACR) strongly recommends against the use of chondroitin for any form of osteoarthritis (102114). Conversely, the European Society of Clinical and Economic Aspects of Osteoarthritis (ESCEO) strongly recommends for the use of pharmaceutical-grade chondroitin products. Additionally, the ESCEO provides a weak recommendation against the use of chondroitin in combination with glucosamine (102141). These differing recommendations seem to be related to interpretation of the evidence for pharmaceutical-grade products. The ACR has determined that the inconsistent evidence may indicate the presence of industry bias; the ESCEO has determined that the inconsistent evidence is due to inconsistent product quality. Chondroitin is often used in combination with glucosamine and/or other products. Long-term studies in patients with osteoarthritis show that taking non-branded chondroitin sulfate with glucosamine sulfate modestly reduces joint-space narrowing when compared with control (89558,94380,95792). However, meta-analyses and individual clinical studies assessing non-branded preparations of chondroitin sulfate with glucosamine hydrochloride or glucosamine sulfate do not show reduced pain in patients with knee osteoarthritis when compared with control (13579,89558,95788,99683,99685). In contrast, pain reduction was reported for branded formulations such as chondroitin sulfate with glucosamine hydrochloride and manganese ascorbate (Cosamin DS, Nutramax Laboratories) (4237,7169); chondroitin sulfate with glucosamine hydrochloride (Droglican, Bioiberica, S.A.) (89516); or chondroitin sulfate with collagen peptides and hyaluronic acid (BioCell Collagen, BioCell Technology, LLC) (28678,28680). A large, prospective observational study in adults with knee or hip osteoarthritis suggests that taking glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg (Theraflex, Bayer) three times daily for the first 3 weeks, then twice daily thereafter for up to 64 weeks, is associated with reductions in pain, stiffness, and the need for concomitant analgesic therapy, and improvements in daily function and knee- or hip-related quality of life, when compared to baseline. The most pronounced improvements are from 16-24 weeks (111647). It is unclear if the benefit seen with these specific products is due to bias introduced by industry funding or due to higher quality. Limited research has also evaluated INTRAMUSCULAR and TOPICAL chondroitin. Some clinical research shows that receiving daily intramuscular injections of chondroitin sulfate for 6 months improves pain and function in patients with osteoarthritis (42396,42397). A topical preparation of chondroitin sulfate in combination with glucosamine sulfate, shark cartilage, and camphor also seems to reduce arthritis symptoms. However, any symptom relief is most likely due to the counterirritant effect of camphor and not the other ingredients (10327). There is no research showing that chondroitin is absorbed topically.

INSUFFICIENT RELIABLE EVIDENCE to RATE

Aging skin. Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in females with aging skin shows that taking a specific combination product (BioCell Collagen, BioCell Technology, LLC) containing chondroitin sulfate 200 mg, collagen peptides 600 mg, and hyaluronic acid 100 mg daily for 12 weeks reduces lines and wrinkles by about 13% when compared with baseline (28681). The validity of these findings is limited by the lack of a comparator group. It is also unclear if these improvements are due to chondroitin sulfate, other ingredients, or the combination. Furthermore, it should be noted that this study was funded by the product manufacturer.
Aromatase inhibitor-induced arthralgia. Oral chondroitin sulfate has only been evaluated in combination with glucosamine sulfate; its effect when used alone is unclear. Details: A small open-label clinical study in postmenopausal females with early stage breast cancer shows that taking a combination of glucosamine sulfate 1500 mg and chondroitin sulfate 1200 mg in 2-3 divided doses daily for 24 weeks improves pain and symptoms associated with aromatase inhibitor-induced arthralgias when compared to baseline (89561). The validity of this finding is limited by the lack of a control group.
Cancer. Some low-quality observational studies suggest that oral chondroitin use is not associated with a lower risk of cancer. Details: A meta-analysis of observational research has found that use of chondroitin with or without glucosamine is not associated with a lower risk of cancer when compared with no use (110625).
Colorectal adenoma. Oral chondroitin has only been evaluated in combination with glucosamine; its effect when used alone is unclear. Details: An observational study in older adults has found that taking oral chondroitin and glucosamine is associated with a 26% reduced chance of high-risk adenoma and 10% reduced chance of conventional adenoma when compared with not using these supplements. This benefit was not seen in a subgroup of younger females (104444).
Dry eye. It is unclear if ophthalmic chondroitin sulfate improves dry eye symptoms. Details: A small clinical study in patients with dry eye suggests that administering an ophthalmic preparation of chondroitin sulfate every two hours while awake for 2 weeks seems to improve symptoms when compared to baseline (1974). Chondroitin has also been used in combination with other ingredients. A large clinical trial in patients with mild to moderate dry eye disease shows that applying preservative-free eye drops containing chondroitin sulfate with sodium hyaluronate (Humylub Ofteno PF, Laboratorios Sophia), one drop into each eye four times daily for 90 days, seems to be no different for improving dry eye severity when compared with using polyethylene/propylene glycol eye drops (Systane Ultra, Alcon Laboratories) (104443). Another small clinical trial in patients with mild to moderate dry eye shows that using specific eye drops containing chondroitin sulfate and xanthan gum (PRO-148, Laboratorios Sophia) four times daily for 60 days does not improve tear stability, but might improve dry eye severity, when compared with using polyethylene/propylene glycol eye drops (Systane, Alcon Laboratories) (89591).
Exercise-induced muscle soreness. It is unclear if oral chondroitin sulfate improves muscle soreness from exercise. Details: Preliminary clinical research in untrained males shows that taking chondroitin sulfate 1800 mg twice daily for 14 days before exercise does not reduce post-exercise muscle soreness when compared with placebo (42352). However, another small clinical study in healthy, recreationally active adults shows that a specific combination product (BioCell Collagen, BioCell Technology, LLC) containing chondroitin sulfate 300 mg, collagen peptides 900 mg, and hyaluronic acid 150 mg, taken twice daily for 6 weeks prior to two bouts of resistance exercise, attenuates muscle damage and decreases delayed-onset muscle soreness when compared with placebo (96301). It is unclear if these effects are due to chondroitin sulfate, the other ingredients, or the combination.
Gastroesophageal reflux disease (GERD). Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Patients with non-erosive GERD are thought to be less responsive to conventional acid suppression with proton pump inhibiters (PPIs) and H-2 blockers. A small preliminary clinical study shows that taking a syrup containing hyaluronic acid and chondroitin sulfate along with PPIs, H2-receptor antagonists, and/or antacids, reduces the intensity of symptoms associated with non-erosive GERD by about 3.5-fold when compared with placebo (89592). A larger clinical study in patients with non-erosive GERD shows that taking the same combination agent (Esoxx by Alfa Wassermann) in addition to acid suppression with PPIs improves GERD symptom severity by 21%, heartburn by 15%, and regurgitation by 10% when compared with PPIs with a placebo (101271). This product is available in Canada as EsopH (Exzell Pharma). It is unclear if the benefit of this combination product is due to chondroitin sulfate, hyaluronic acid, or the combination. Chondroitin sulfate has also been evaluated in patients with GERD who experience extraesophageal symptoms. A small clinical study in patients reporting symptoms of cough, hoarseness, postnasal drip, sore throat, and/or throat clearing shows that taking a specific combination product (Gerdoff, SOFAR S.p.A.) containing chondroitin sulfate, hyaluronic acid, and aluminum hydroxide three times daily with omeprazole 40 mg once daily for 6 weeks does not reduce overall symptom scores, based on the Reflux Symptoms Index (RSI) score, when compared with omeprazole alone. However, it does increase the probability of treatment response, defined as a 50% or greater improvement in RSI score, by nearly 40% (109648). This product is available in Italy. It is unclear if these findings are due to chondroitin sulfate, other ingredients, or the combination.
Gastritis. Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with gastritis shows that taking a specific liquid product (Esoxx, Alfa Wasserman Spa) containing chondroitin sulfate and hyaluronic acid four times daily for 4 weeks modestly reduces upper abdominal pain when compared with placebo (99687). It is not clear if this effect is due to chondroitin sulfate, hyaluronic acid, or the combination.
Hyperlipidemia. Although there is interest in using oral chondroitin for hyperlipidemia, there is insufficient reliable information about the clinical effects of chondroitin for this condition.
Interstitial cystitis. Small clinical studies suggest that intravesical chondroitin sulfate may not improve interstitial cystitis symptoms. Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Several uncontrolled, open-label studies suggest that intravesical chondroitin sulfate, with or without hyaluronic acid, improves clinical symptoms of interstitial cystitis and reduces the problems caused by symptoms in these patients (42338,42371,42373,42385,42387). However, in controlled clinical trials, intravesical chondroitin sulfate 2%, instilled weekly for 6-7 weeks, does not significantly improve symptoms when compared with a placebo solution (42473,42517). Furthermore, a meta-analysis of clinical research shows that intravesical chondroitin sulfate with hyaluronic acid does not improve pain due to interstitial cystitis better than using hyaluronic acid solution alone (97054). Oral chondroitin has been evaluated in combination with other ingredients. Preliminary clinical research shows that taking a specific product (CystoProtek, Tischon Corporation) containing glucosamine sulfate 120 mg, sodium hyaluronate 10 mg, chondroitin sulfate 150 mg, quercetin 150 mg, and rutin 20 mg, as two capsules twice daily for 12 months, reduces symptoms of interstitial cystitis by 44% to 52% (42391). It is not clear if this effect is due to chondroitin, other ingredients, or the combination.
Kashin-Beck disease. It is unclear if oral chondroitin sulfate improves Kashin-Beck disease symptoms such as pain. Details: A small clinical study in Chinese adults with Kashin-Beck disease shows that taking chondroitin sulfate 600 mg twice daily with or without glucosamine hydrochloride 480 mg three times daily for 6 months decreases pain and stiffness when compared with placebo (42516).
Osteoporosis. Although there is interest in using oral chondroitin for osteoporosis, there is insufficient reliable information about the clinical effects of chondroitin for this condition.
Overall mortality. Oral chondroitin has only been evaluated in combination with glucosamine; its effect when used alone is unclear. Details: A cross-sectional observational study suggests that using oral chondroitin and glucosamine for at least one year is associated with a 27% lower incidence of overall mortality and 58% lower incidence of cardiovascular mortality when compared with not using these supplements (104445). However, this study did not clarify the forms of chondroitin and glucosamine used, or the doses, frequencies, or durations of use. Furthermore, the adults that reported glucosamine and chondroitin use also reported overall healthier lifestyle habits than those that were not taking glucosamine and chondroitin. Another observational study suggests that regular use of chondroitin with glucosamine for an average of 8 years is associated with a 30% lower risk of mortality when compared with no use. However, when these findings are adjusted for differences in age, body mass index, and comorbidities, overall mortality risk does not seem to be reduced with chondroitin and glucosamine supplementation (110626). Higher quality, prospective research is needed to clarify the relationship, if any, with overall mortality. Additionally, it is unclear if the effects on mortality are due to chondroitin, glucosamine, or the combination.
Psoriasis. It is unclear if oral chondroitin sulfate is beneficial for reducing psoriasis disease severity. Details: A clinical study in patients with plaque psoriasis and knee osteoarthritis shows that taking chondroitin sulfate (Condrosan, CS Bio-Active, Bioibérica S.A.) 800 mg daily for 3 months does not appear to reduce the extent or severity of plaque psoriasis when compared with placebo (42463).
Stroke. It is unclear if oral chondroitin sulfate is beneficial for reducing stroke risk. Details: An observational study in Spanish patients found that chondroitin sulfate use is associated with 23% lower odds of ischemic stroke when compared with non-use; however, the benefit was only observed in patients taking at least 800 mg for no more than one year (109643).
Temporomandibular disorders (TMD). Oral and topical chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of two small clinical studies in patients with TMD shows that taking chondroitin sulfate 1200 mg and glucosamine sulfate 1500 mg daily for 2 months does not reduce pain or increase maximum mouth opening when compared with tramadol 50-100 mg daily (109647). Another small clinical trial in children aged 10-13 years with class II malocclusion shows that application of a specific combination gel product containing glucosamine, chondroitin, and essential oils (Jointace Gel, Vitabiotics) with an expander device twice daily for 3 months does not improve pain, tension, or temporomandibular space measures when compared with placebo (110629).
Urinary incontinence. Although there is interest in using intravesical chondroitin for urinary incontinence, there is insufficient reliable information about the clinical effects of chondroitin for this condition.
Urinary tract infections (UTIs). It is unclear if intravesical administration of chondroitin sulfate alone is beneficial in patients with recurrent UTIs. Most research has evaluated the effects of chondroitin sulfate in combination with hyaluronic acid, with promising results. Details: One small observational study in patients with recurrent UTIs has found that intravesical administration of 40 mL of chondroitin sulfate 0.2% weekly for 6 weeks, then every 2 weeks for 2 months, then every 3 weeks for 2 months, and finally every 6 weeks for a total treatment duration of 1 year is associated with a lower number of UTIs and urologist visits when compared with low-dose long-term antibiotic therapy (109649). Most research on the use of chondroitin sulfate for UTIs has evaluated its effects when used in combination with hyaluronic acid. Several small clinical studies and a pooled analysis of the available clinical research show that intravesical administration of 50 mL of specific solutions containing chondroitin sulfate 2% and hyaluronic acid 1.6% (iAluRil, IBSA Farmaceutici; Cystistat, Bioniche) for up to 6 months reduces the rate of UTI recurrence by about 2-3 incidents per year and delays the time to the first UTI recurrence when compared with placebo or prophylaxis with sulfamethoxazole-trimethoprim (42511,42519,89590,89594,99688). However, the validity of these findings is limited by the low quality and high heterogeneity of the included studies, as well as concerns for publication bias (99688). More evidence is needed to rate chondroitin sulfate for these uses.

GLUCOSAMINE (Glucosamine Sulphate)

LIKELY EFFECTIVE

Osteoarthritis. Oral glucosamine sulfate taken for at least 4 weeks is modestly beneficial for improving pain and function in knee osteoarthritis. However, oral glucosamine hydrochloride seems to only be beneficial when used in combination with chondroitin and other ingredients. It is unclear if glucosamine can slow disease progression or improve symptoms in other forms of osteoarthritis. Details: Meta-analyses of the available research in adults with KNEE osteoarthritis show that taking glucosamine SULFATE 1500 mg daily for up to 3 years modestly improves pain, function, and joint space narrowing when compared with placebo (14305,89521,94382,95785,99684,113636). Individual studies show 28% to 41% pain reduction and 21% to 46% improvement in function when compared with placebo (7026,8942,12461,20084,94382). Some research suggests that glucosamine sulfate reduces pain similarly to various non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen 400 mg three times daily and piroxicam 20 mg daily. However, NSAIDs appear to relieve symptoms within 2 weeks, while glucosamine sulfate takes 4-8 weeks. Notably, glucosamine sulfate appears to sustain benefit for longer after treatment withdrawal when compared with piroxicam (2604,20094,20096). Other clinical research shows that glucosamine sulfate 1500 mg once daily for 6 months might be more effective for reducing symptoms than acetaminophen 1 gram three times daily or 650 mg once daily in patients with moderate knee osteoarthritis (13578,20098). However, not all research shows benefit. One meta-analysis of clinical studies in adults with knee osteoarthritis shows that taking glucosamine sulfate 1500 mg daily for 4 weeks to 3 years reduces some, but not all, measures of pain intensity and does not reduce pain when moving or improve function when compared with placebo (113636). Furthermore, small clinical studies suggest that glucosamine sulfate 1500 mg daily for 2-6 months may NOT work for severe, long-standing osteoarthritis (1330,11459). It is unclear if glucosamine sulfate can slow disease progression. A specific crystalline glucosamine sulfate product (Dona, Rotta Pharmaceuticals) taken as 1500 mg daily for up to 3 years seems to prevent joint space narrowing of greater than 0.5 mm by up to 54% when compared with placebo (7026,8942,13719,42420). In contrast, other glucosamine sulfate formulations have not consistently been shown to improve symptoms or prevent joint space narrowing when compared with placebo (14305,89558,94382,95788). It is unclear if the benefit seen with this specific product (Dona) is due to bias introduced by industry funding or due to a higher quality product (42492). Glucosamine products associated with quality concerns have demonstrated inconsistent benefits in research (8128,102116). Limited research on the use of a different salt, glucosamine HYDROCHLORIDE, has found no benefit for knee osteoarthritis. A meta-analysis of clinical research and two other clinical trials show that taking glucosamine hydrochloride 1500 mg daily for up to 18 months does not seem to reduce pain when compared with placebo (18344,89519,89521). However, one small, unblinded clinical study in patients with mild to moderate osteoarthritis shows that taking a combination of glucosamine hydrochloride 480 mg every 12 hours and celecoxib 200 mg daily reduces pain scores, osteoarthritis severity, and inflammatory markers to a greater extent than celecoxib alone (106883). There is mixed evidence of benefit when glucosamine hydrochloride is used with chondroitin. Clinical research in patients over 40 years of age shows that taking a noncommercial preparation of glucosamine hydrochloride 1500 mg daily in combination with chondroitin sulfate 1200 mg daily for 6-24 months does not reduce pain when compared with placebo. The placebo response in these studies was sometimes as high as 60% (13579,14809,42477). However, a large, prospective observational study in adults with knee or hip osteoarthritis suggests that taking glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg (Theraflex, Bayer) three times daily for the first 3 weeks then twice daily thereafter for up to 64 weeks is associated with reductions in pain, stiffness, and the need for concomitant analgesic therapy and improvements in daily function and knee- or hip-related quality of life when compared to baseline. The most pronounced improvements were from 16-24 weeks (111647). The validity of these effects is limited by subjective outcomes, a lack of control group, and the observational design of the study. Furthermore, another clinical trial shows that taking a prescription product available in Spain (Droglican, Bioibérica S.A.), providing a similar daily dose of glucosamine hydrochloride with chondroitin sulfate for 6 months is non-inferior to celecoxib 200 mg daily for relieving pain, but not stiffness or function (89516). Small clinical studies show that taking a specific combination product (Cosamin or Cosamin DS, Nutramax Laboratories) containing glucosamine hydrochloride 1500-2000 mg, low molecular weight chondroitin sulfate 1200-1600 mg, and manganese ascorbate 228-304 mg, in 2-3 divided doses daily for 2-6 months improves pain in patients with mild or moderate, but not severe, osteoarthritis when compared with placebo (4237,7169). A different combination product (Gurukosamin & Kondoroichin, Suntory Wellness Ltd.) containing glucosamine hydrochloride 1200 mg, chondroitin sulfate 60 mg, and quercetin glycosides 45 mg, taken daily for 16 weeks, also seems to improve symptoms of knee osteoarthritis when compared with placebo (42514). It is unclear if the findings of any of these studies are due to glucosamine, chondroitin, other ingredients, or the combination. Despite evidence suggesting differing benefit (89521,94382), head-to-head comparisons of glucosamine sulfate and glucosamine hydrochloride are limited, and it is not universally acknowledged that these salts have different effectiveness profiles. One large clinical study in patients with knee osteoarthritis shows that taking a specific product (Artrolive, Aché Laboratórios Farmacêuticos S.A.) containing glucosamine sulfate 500 mg and chondroitin sulfate 400 mg three times daily for 4 months seems to be no different for reducing pain when compared with taking glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg (Cosamin DS, Nutramax Laboratories, Inc.) three times daily (89520). This study was funded by the supplement manufacturer. Many meta-analyses have pooled studies of both glucosamine salts together, producing largely inconsistent results (94381,99683,99685,112444). Experts have conflicting stances on the use of glucosamine. The American College of Rheumatology (ACR) strongly recommends against the use of any glucosamine products for any form of osteoarthritis (102114). Conversely, the European Society of Clinical and Economic Aspects of Osteoarthritis (ESCEO) strongly recommends the use of pharmaceutical-grade glucosamine sulfate products, such as Dona (Rotta Pharmaceuticals), in patients with osteoarthritis. Additionally, the ESCEO provides a weak recommendation against the use of glucosamine in combination with chondroitin (102141). These differing recommendations seem to be related to interpretation of the evidence for pharmaceutical-grade products. The ACR has determined that the inconsistent evidence may indicate the presence of industry bias; the ESCEO has determined that the inconsistent evidence is due to inconsistent product quality. Limited research has found mixed benefit of using glucosamine on osteoarthritis of the SPINE, HIP, or HAND. In one study of patients with osteoarthritis of the lumbar spine, taking glucosamine sulfate (Dona, Rotta Pharmaceuticals) 1500 mg daily for 6 weeks reduced pain in more patients when compared with placebo (1316). However, in another study, using a different glucosamine sulfate product (Glucosamine Sulfate, PharmaNord) 1500 mg daily for 6 months did not reduce pain when compared with placebo (89562). In patients with hip osteoarthritis, taking glucosamine sulfate 1500 mg once daily for 2 years did not reduce symptoms or slow disease progression when compared with placebo (16717,20100); however, there was a high rate of hip replacement, which may have confounded results (16717,16718). In patients with erosive osteoarthritis of the hand, observational research has found that taking glucosamine sulfate (Dona, Rotta Pharmaceuticals) 1500 mg daily along with conventional therapy for 6 months is associated with reduced hand pain, a shorter duration of morning stiffness, and improved hand function when compared with conventional therapy alone (108897). Limited research has also evaluated INTRAMUSCULAR and TOPICAL glucosamine sulfate. A clinical study in patients with mild to moderate knee osteoarthritis (radiological stage I-III) shows that giving intramuscular glucosamine sulfate 400 mg twice per week for 6 weeks reduces the severity of symptoms when compared with placebo (2605). There is also a small study showing that a topical preparation of glucosamine sulfate in combination with chondroitin sulfate, shark cartilage, and camphor reduces osteoarthritis symptoms when compared with placebo. However, any symptom relief is most likely due to the counterirritant effect of camphor and not the other ingredients (10327,12467). There is no evidence that glucosamine is absorbed topically. Glucosamine sulfate does not seem to PREVENT osteoarthritis. Clinical studies in overweight healthy females aged 50-60 years shows that taking crystalline glucosamine sulfate 1500 mg orally daily for 2.5 years does not reduce the incidence of osteoarthritis after a 6-7 year follow-up; however, it may reduce the percentage of patients who experience knee joint space narrowing (95789,97053).

INSUFFICIENT RELIABLE EVIDENCE to RATE

Aging skin. Topical N-acetyl glucosamine has only been evaluated in combination with niacinamide for reducing hyperpigmentation and liver skin spots on aging skin; its effect when used alone is unclear. Details: A clinical study in females ages 40-60 years with skin hyperpigmentation and solar lentigines (liver spots) primarily due to aging and sun exposure shows that applying a cream containing 2% N-acetyl glucosamine and 4% niacinamide to the face twice daily with sunscreen for 10 weeks decreases facial hyperpigmentation when compared with sunscreen alone (92721). The effect of N-acetyl glucosamine alone is unclear.
Aromatase inhibitor-induced arthralgia. Oral glucosamine sulfate has only been evaluated in combination with chondroitin; its effect when used alone is unclear. Details: A small open-label clinical study in patients with aromatase inhibitor-induced arthralgia shows that taking a combination of glucosamine sulfate 1500 mg and chondroitin sulfate 1200 mg in 2-3 divided doses daily for 24 weeks improves pain when compared to baseline in postmenopausal adults with early stage breast cancer (89561). The validity of this finding is limited by a lack of control group.
Back pain. Although there is interest in using oral glucosamine for back pain, there is insufficient reliable information about the clinical effects of glucosamine for this condition.
Cancer. Some low-quality observational studies have inconsistently found that glucosamine may be associated with a lower risk of different cancers; however, better quality evidence is needed. Details: A meta-analysis of observational research has found that use of glucosamine with or without chondroitin is associated with a 7% to 12% lower risk of cancer when compared with no use of glucosamine. A subgroup analysis showed a reduction in the risk of colorectal cancer, but not other types of cancer (110625). Observational research report conflicting relationships between glucosamine and cancer. Some observational research in adults in the United Kingdom has found that taking glucosamine is associated with 4% higher risk of cancer over a median follow up for 13 years. However, a subgroup analysis showed a reduction in the risk of lung cancer (110627). Other observational research in adults in the United Kingdom has found that taking glucosamine is associated with a 5% reduced risk of cancer mortality over a median follow-up of around 12 years, with reductions specifically occurring in those with kidney, lung, and rectal cancers. However, glucosamine use was not linked to a reduced risk of mortality due to bladder, brain, breast, colon, ovarian, prostate, skin, stomach, thyroid, or uterine cancer (109645). Other large, propensity-score-adjusted, observational research in adults with osteoarthritis in the United Kingdom suggests that treatment with glucosamine, with an average of 8 years of follow-up, is not associated with a reduction in cancer, including lung, colorectal, breast, or prostate cancer, when compared with patients not prescribed glucosamine (114571). These studies are limited by observational designs, which also did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Although some studies attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and the risk for cancer and/or cancer-related mortality. Of note, some researchers have called into question the results from observational research linking glucosamine use to a lower rate of cancer, claiming that these studies suffer from a high risk of selection bias (109646).
Cardiovascular disease (CVD). It is unclear if oral glucosamine prevents fatal or non-fatal CVD events. Details: Some observational research of adults in the United Kingdom has found that taking glucosamine is associated with an overall 15% reduced risk for fatal and non-fatal CVD events, including coronary heart disease (CHD) and stroke (99682). However, this study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Conversely, an observational study in Chinese patients with osteoarthritis has found that glucosamine use is associated with a 10% increase in the risk of CVD events and a 12% increase in the risk of CHD, with no increase in the risk of stroke. The risk for these outcomes was greatest in patients with higher adherence to glucosamine and in those taking larger doses (109642). However, this study also did not clarify the form of glucosamine used or provide specifics related to the frequency or duration of use. Furthermore, glucosamine users were generally older, more likely to be on antihyperlipidemic or antiplatelet therapy, and more likely to have multiple comorbidities compared with non-users. Both studies attempted to control for the differences in characteristics between glucosamine users and non-users; despite this, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and CVD risk.
Colorectal adenoma. Oral glucosamine has only been evaluated in combination with chondroitin; its effect when used alone is unclear. Details: An observational study in older adults has found that taking glucosamine and chondroitin is associated with a 26% reduced risk of high-risk adenoma and 10% reduced risk of conventional adenoma when compared with not using these supplements. This benefit was not seen in a subgroup of younger females (104444). This study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use.
Colorectal cancer. It is unclear if oral glucosamine reduces the risk of colorectal cancer. Details: A meta-analysis of observational research has found that use of glucosamine with or without chondroitin is associated with a 7% to 12% lower risk of cancer when compared with no use of glucosamine. A subgroup analysis showed a reduction in the risk of colorectal cancer, but not other types of cancer (110625). However, not all research agrees. A large, observational study in adults has found that regular use of oral glucosamine is not associated with a reduced risk of colorectal cancer over a median of 7 years of follow-up, regardless of sex, age, body mass index, smoking status, or non-steroidal anti-inflammatory drug use (108018). Other large, propensity-score-adjusted, observational research in adults with osteoarthritis in the United Kingdom suggests that treatment with glucosamine, with an average of 8 years of follow-up, is not associated with a reduction in cancer, including colorectal cancer, when compared with patients not prescribed glucosamine (114571).These studies did not clarify the form or dose of glucosamine used or the frequency or duration of use.
Coronavirus disease 2019 (COVID-19). It is unclear if oral glucosamine is beneficial for COVID-19. Details: A large observational study in adults suggests that regular glucosamine use over a median of 1.7 years is not linked to a lower odds of COVID-19 infection but is associated with a 20% lower risk of hospital admission and a 19% lower risk of mortality due to COVID-19 when compared with adults not using glucosamine (111649). This study did not clarify the form or dose of glucosamine used or the frequency or duration of use.
Dementia. Observational studies suggest that long-term, regular glucosamine intake might reduce the risk of developing certain types of dementia. Details: An observational study has found that regularly taking glucosamine for an average of 8.9 years is associated with a 19% lower risk of developing dementia, including Alzheimer disease and vascular dementia (110630). Another large observational study in older adults without dementia suggests that regularly taking glucosamine for a median of 12 years is associated with an 18% lower risk of vascular dementia. However, habitual glucosamine consumption is not associated with a reduced risk of Alzheimer disease or frontotemporal dementia (112461).
Depression. It is unclear if oral glucosamine hydrochloride reduces depression symptoms. Details: A small, open-label clinical trial in patients with unipolar depression shows that taking glucosamine hydrochloride 1 gram daily for 1 week, followed by 2 grams daily for 3 weeks, reduces scores on the Hamilton Rating Scale for Depression (HAM-D) and Montgomery-Asberg Depression Rating Scale (MADRS) by 31% or 33% when compared to baseline. However, only 20% of patients experienced a 50% or greater reduction in HAM-D scores, and there were no improvements in Clinical Global Impression scores (103281). The lack of a control group limits the validity of these findings.
Diabetes. It is unclear if oral glucosamine reduces the risk of developing type 2 diabetes in adults. Details: Observational research in adults in the United Kingdom has found that glucosamine use is associated with a 17% lower risk of type 2 diabetes. The relationship between glucosamine use and diabetes appears to be even more pronounced in patients with high baseline levels of C-reactive protein, a marker of inflammation (103234). However, this study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Although this study attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and the risk for diabetes.
Gout. It is unclear if oral glucosamine reduces the risk of developing gout. Details: Observational research in adults in the United Kingdom has found that glucosamine use is associated with a 19% lower risk of gout in females, but not males (109644). However, this study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Although this study attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and the risk for gout.
Heart failure. It is unclear if oral glucosamine prevents heart failure. Details: A large, prospective observational study in adults without heart failure suggests that taking glucosamine regularly over a median of 9 years is associated with a 13% lower risk of developing heart failure when compared with adults not taking glucosamine (111646). This study did not clarify the form or dose of glucosamine used or the frequency or duration of use.
Hyperlipidemia. It is unclear if oral glucosamine hydrochloride improves hyperlipidemia when used with conventional medicine. Details: Preliminary clinical research shows that glucosamine hydrochloride does not reduce cholesterol or triglyceride levels in patients with hyperlipidemia. A small crossover study in older adults taking simvastatin or atorvastatin shows that adding a specific glucosamine hydrochloride product (Artrox, Pfizer) 750 mg twice daily for 4 weeks does not seem to affect lipid levels when compared with placebo (18341).
Inflammatory bowel disease (IBD). It is unclear if oral or rectal N-acetyl glucosamine improves symptoms of IBD in children. Details: A very small clinical study in children ages 8-17 years with Crohn disease or ulcerative colitis that were unresponsive to conventional treatment suggests that oral or rectal N-acetyl glucosamine 1.5-2 grams in 10 mL water twice daily for 6 weeks might decrease symptoms of IBD when compared with baseline (10234). The validity of this finding is limited by a lack of control group.
Interstitial cystitis. Oral glucosamine sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: An open-label clinical study in patients with interstitial cystitis shows that taking a specific product (CystoProtek, Tischon Corporation) containing glucosamine sulfate 120 mg, sodium hyaluronate 10 mg, chondroitin sulfate 150 mg, quercetin 150 mg, and rutin 20 mg per capsule, as two capsules twice daily for 12 months, reduces symptom severity by up to 52% when compared with baseline (42391). The validity of this finding is limited by a lack of control group.
Joint pain. Oral glucosamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with joint pain shows that taking capsules of a specific combination product (Instaflex Joint Support, Direct Digital) containing glucosamine sulfate 1500 mg, methylsulfonylmethane 500 mg, white willow bark extract 250 mg, ginger root concentrate 50 mg, Boswellia serrata extract 125 mg, turmeric root extract 50 mg, cayenne 40 m H.U. 50 mg, and hyaluronic acid 4 mg, daily in three divided doses for 8 weeks, reduces joint pain severity by 37% compared to only 16% with placebo. However, the specific combination product does not appear to improve joint stiffness or function compared with placebo (89560).
Kashin-Beck Disease. It is unclear if oral glucosamine hydrochloride improves Kashin-Beck Disease symptoms such as pain. Details: A small clinical study in Chinese adults with Kashin-Beck Disease shows that taking glucosamine hydrochloride 480 mg three times daily along with chondroitin sulfate 600 mg twice daily for 6 months decreases pain scores by at least 20% to 50% in more patients when compared with placebo. Taking glucosamine alone had a non-significant trend toward pain reduction in these patients (42516). An open-label study in Chinese adults with Kashin-Beck Disease shows that taking glucosamine hydrochloride 750 mg twice daily for 6 weeks seems to be no different for improving pain and physical function when compared with taking to diclofenac 50 mg twice daily or naproxen 300 mg twice daily (18339). The validity of this finding is limited by a lack of blinding.
Kidney stones (nephrolithiasis). Oral glucosamine might reduce the risk of developing kidney stones. Details: A large observational study in adults without kidney stones suggests that regularly taking glucosamine is associated with a 28% lower risk of new-onset kidney stones in people with a total sedentary time under 3.5 hours daily. This association follows a dose-dependent relationship. However, regular glucosamine use does not seem to reduce the risk of new-onset kidney stones in people with total sedentary time exceeding 3.5 hours daily (112451).
Knee pain. Small clinical studies suggest that oral glucosamine hydrochloride might improve exercise-induced knee pain and chronic knee pain. However, it is unclear if glucosamine sulfate, N-acetyl glucosamine, or lower doses of glucosamine hydrochloride are beneficial in these patients. Details: A small clinical study in athletes following an acute knee injury shows that taking glucosamine sulfate 500 mg three times daily for 28 days does not improve pain but might modestly improve mobility when compared with placebo (20103). Glucosamine has also been evaluated for chronic knee pain. A small clinical study in patients with chronic knee pain of unclear origin shows that taking glucosamine hydrochloride 2000 mg daily for 12 weeks might modestly improve pain when compared with placebo (10312). However, lower doses of glucosamine hydrochloride and N-acetyl glucosamine used in combination with other ingredients have not demonstrated benefit for chronic knee pain. A small clinical trial in Japanese adults over 40 with knee pain shows that taking a combination supplement with glucosamine hydrochloride and other ingredients for 16 weeks does not improve pain, function, or walking speed when compared with placebo. The combination supplement provided glucosamine hydrochloride 1200 mg, chondroitin sulfate 60 mg, type II collagen peptides 45 mg, quercetin glycosides 90 mg, imidazole peptides 10 mg, and vitamin D 200 IU daily (95784). Another small clinical study in Japanese patients over 50 years of age with chronic knee pain shows that taking a specific supplement (Walker's Glucosamine, Kyowa) containing N-acetyl glucosamine 100 mg and chondroitin sulfate 180 mg daily for 24 weeks does not reduce pain or improve knee function when compared with placebo (95795).
Metabolic dysfunction-associated steatotic liver disease (MASLD). It is unclear if oral glucosamine is beneficial in patients with MASLD. Details: Observational research in adults with MASLD and type 2 diabetes suggests that regular use of glucosamine orally for an average follow up of 11 years is associated with a lower risk of adverse liver outcomes when compared with those not regularly using glucosamine. Non-users of glucosamine had 35% to 44% higher risk of cirrhosis, encephalopathy, and esophageal varices. This study did not report the glucosamine dose or frequency (114573).
Multiple sclerosis (MS). It is unclear if oral glucosamine sulfate is beneficial in patients with MS. Details: A small clinical study in patients with MS shows that taking glucosamine sulfate 1000 mg once daily for 6 months modestly reduces relapse when compared to baseline, but not when compared with placebo (20104).
Overall mortality. It is unclear if oral glucosamine reduces overall mortality. Details: An observational study in the United States has found that regular use of oral glucosamine, with or without chondroitin, for an average of 8 years is associated with a 30% lower risk of mortality when compared with no glucosamine use. However, when adjusted for covariates such as age, body-mass index, and comorbidities, there was no difference in overall mortality (110626). In contrast, a cross-sectional observational study has found that using oral glucosamine and chondroitin for at least one year is associated with 27% reduced incidence of overall mortality and 58% reduced incidence of cardiovascular mortality when compared with not using these supplements (104445). This study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine and chondroitin use also reported overall healthier lifestyle habits than those that were not taking glucosamine and chondroitin. Although this study attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, with overall mortality. Of note, some researchers have called into question the results from observational research linking glucosamine use to a lower rate of overall mortality, claiming that these studies suffer from a high risk of selection bias (109646).
Postoperative recovery. It is unclear if oral glucosamine sulfate improves recovery after surgery. Details: A small clinical study in male athletes who have undergone anterior cruciate ligament (ACL) reconstruction shows that taking glucosamine sulfate (Solgar Inc.) 1000 mg daily for 8 weeks does not improve rehabilitation outcomes such as functional ability, pain, and muscular performance when compared with placebo (95584).
Rheumatoid arthritis (RA). It is unclear if oral glucosamine hydrochloride is beneficial in patients with RA. Details: A small clinical study in patients with RA shows that taking glucosamine hydrochloride tablets (Rohto Pharmaceutical Co.) 500 mg three times daily by mouth for 12 weeks reduces pain, but not the number of painful or swollen joints, when compared with placebo (17407).
Stroke. It is unclear if oral glucosamine is beneficial for reducing stroke risk. Details: An observational cohort study of adults in the United Kingdom found that taking glucosamine is associated with a modest 9% reduced risk for overall stroke; however, sub-analyses show that glucosamine use is not associated with a reduced risk for fatal or non-fatal stroke, hemorrhagic stroke, or ischemic stroke (99682). This study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. A case-control study in Spanish patients found that glucosamine use is associated with 45% lower odds of ischemic stroke when compared with non-use; however, the benefit was only observed in patients taking glucosamine for 1 year or less (109643). This study did not clarify the form of glucosamine used or the dose or frequency of use. Furthermore, patients in the control group were generally healthier and less likely to have a history of cardiovascular disease, diabetes, or hyperlipidemia. Although both studies attempted to control for differences between patient populations, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and stroke risk.
Temporomandibular disorders (TMD). It is unclear if oral glucosamine sulfate is beneficial in patients with temporomandibular joint osteoarthritis. Details: A small and low-quality clinical study in patients with temporomandibular joint osteoarthritis shows that taking glucosamine sulfate 500 mg three times daily for 90 days seems to be no different than taking ibuprofen 400 mg three times daily for relieving pain and improving functional abilities such as chewing, yawning, talking, and laughing (3714). However, another small clinical study in patients with the same condition shows that taking glucosamine sulfate 1200 mg daily for 6 weeks does not improve pain or jaw opening capacity when compared with placebo (20105). Glucosamine sulfate has also been evaluated in combination with chondroitin for this condition. A meta-analysis of two small clinical studies in patients with TMD shows that taking glucosamine sulfate 1500 mg and chondroitin sulfate 1200 mg daily for 2 months does not reduce pain or increase maximum mouth opening when compared with tramadol 50-100 mg daily (109647). Other meta-analyses have reported similar results, however, these analyses may have been inadequately powered to detect a difference between groups (114572). Another small clinical trial in children aged 10-13 years with class II malocclusion shows that application of a specific combination gel product containing glucosamine, chondroitin, and essential oils (Jointace Gel, Vitabiotics) with an expander device, twice daily for 3 months does not improve temporomandibular space measures or pain or tension scores, when compared with placebo (110629).
Wound healing. Although there is interest in using topical glucosamine for wound healing, there is insufficient reliable information about the clinical effects of glucosamine for this condition. More evidence is needed to rate glucosamine for these uses.

(Read more about GLUCOSAMINE)

SELENIUM

LIKELY EFFECTIVE

Selenium deficiency. Oral selenium is effective for the treatment and prevention of selenium deficiency. Details: Selenium supplementation is effective for reversing symptoms of selenium deficiency, as well as for preventing the development of selenium deficiency (4844,90357).

POSSIBLY EFFECTIVE

Autoimmune thyroiditis. Oral selenium seems to improve autoimmune thyroiditis in adults but not in children. Details: Clinical research in adults with thyroiditis shows that taking selenium up to 200 mcg daily in combination with levothyroxine reduces thyroid peroxidase antibodies by about 6% to 30% more than placebo after 3-12 months of treatment (9797,17510,17511,17512,17513,17515,17516,97943,104424). Selenium also seems to improve measures of quality of life such as feelings of well-being and mood (17515). Doses under 200 mcg daily might not be as effective (17512); selenomethionine might be more effective than sodium selenite (97943). Some research shows that selenium might be more effective in patients with more severe disease activity and less effective in patients with only moderate disease activity (9797,17513,17515). Also, selenium might not reduce thyroid autoantibodies in patients newly diagnosed with thyroiditis not receiving concurrent levothyroxine (97943). There is no reliable evidence about the effect of selenium on thyroid function or thyroid morphology. Despite positive findings in adults, clinical research in children suggests that taking selenium 50-200 mcg daily for 3-12 months does not significantly improve thyroid peroxidase antibodies, thyroglobulin antibody, or thyroid echogenicity (17514,90362).
Kashin-Beck disease. Selenium seems to help prevent Kashin-Beck disease, but does not improve symptoms in patients with existing disease. Details: A meta-analysis of prospective studies conducted in China shows that adding salt enriched with selenium to the diet of healthy children for up to 4 years reduces the odds of developing Kashin-Beck disease by 84% when compared with the use of iodine salt. Additionally, in children with Kashin-Beck disease, adding salt enriched with selenium to the diet might help heal metaphyseal lesions (97945). However, selenium does not seem to improve symptoms in those with existing disease. A clinical trial in children with Kashin-Beck disease shows that selenium supplementation does not improve joint pain or mobility when compared with placebo (55941).
Pre-eclampsia. Oral selenium might reduce the risk of pre-eclampsia in pregnant patients. Details: A meta-analysis of three low-quality clinical trials in pregnant patients shows that taking selenium 60-100 mcg daily for up to 6 months reduces the risk of pre-eclampsia by 72% when compared with placebo. Additionally, a meta-analysis of population research has found that the risk of pre-eclampsia is higher in pregnant patients with low selenium levels. Selenium levels were about 6.5 mcg/L lower in those who developed pre-eclampsia compared with those who did not (97946).

POSSIBLY INEFFECTIVE

Asthma. Oral selenium does not seem to improve asthma symptoms. Details: Epidemiological research has found that plasma selenium concentration is not associated with asthma (74422). Also, clinical research in patients with asthma shows that taking selenium 100 mcg daily for 14-24 weeks does not improve symptoms, lung function, use of rescue inhalers, or quality of life when compared with placebo (74490,74387).
Atopic dermatitis (eczema). Oral selenium-enriched yeast does not seem to improve eczema symptoms. Details: A small clinical study in patients with eczema shows that taking selenium-enriched yeast 600 mcg daily for 12 weeks, either alone or in combination with vitamin E 600 IU daily, does not improve symptom severity when compared with placebo (74456).
Bladder cancer. Despite promising initial research, oral selenium does not seem to prevent bladder cancer development or recurrence. Details: In 2009, the US Food and Drug Administration (FDA) approved a qualified health claim regarding selenium and bladder cancer risk based on two small studies. However, the FDA determined that it is highly uncertain that selenium supplements reduce the risk of bladder cancer (102373). Since that time, the available research has not confirmed an association between selenium and bladder cancer risk. Epidemiological research has found that selenium supplementation is not associated with a reduced risk of bladder cancer (97085). Furthermore, a clinical study shows that taking selenium 200 mcg daily with or without vitamin E 400 IU daily for about 7 years does not prevent bladder cancer in older men (90352). Selenium also does not seem to prevent bladder cancer recurrence. A clinical study shows that taking selenium yeast 200 mcg daily for 3 years does not prevent the recurrence of bladder cancer when compared with placebo in patients that had undergone a transurethral resection for non-invasive bladder cancer (97087).
Cardiovascular disease (CVD). Most research shows that oral selenium does not reduce the risk of CVD. Details: Meta-analyses of clinical trials in patients with and without risk factors for CVD show that taking selenium alone or with other supplements for up to 8 years does not reduce the risk of CVD mortality or fatal and non-fatal CVD events (90360,97078). When reported, patients in these studies all had adequate plasma selenium levels at baseline (90360).
Colorectal cancer. Oral selenium does not seem to prevent cancer of the colon and rectum. Details: Epidemiological research has found no association between serum concentrations of selenium and the risk of developing colorectal cancer (74321,97085). Also, meta-analyses of clinical research, as well as individual clinical trials, show that taking selenium 100-200 mcg daily, alone or in combination with other vitamins and minerals, does not reduce the risk of colorectal cancer when compared with control (16707,34676,90361,97092).
Diabetes. Increased intake of selenium, either in the diet or as a supplement, is associated with an increased risk for developing type 2 diabetes. It is unclear if oral selenium is beneficial in patients with type 2 diabetes. Details: Observational research has found that high serum selenium levels, high dietary selenium intake, and selenium supplementation are each linked to an increased risk of developing diabetes (97091,99661). Consuming more than the recommended dietary allowance (RDA) of selenium daily is associated with an increased risk of developing diabetes when compared with consuming less than the RDA (99661). However, the effect of short-term selenium supplementation in patients with diabetes is unclear. Three small clinical trials in patients with type 2 diabetes and various other conditions, such as cardiovascular disease or kidney failure, show that taking selenium (Nature Made) 200 mcg daily for 8-24 weeks does not improve fasting blood glucose. However, taking selenium seems to reduce insulin resistance and improve insulin sensitivity and levels of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol when compared with placebo (97084,97086,109092). These three studies were included in a meta-analysis of 10 small, mostly moderate-quality clinical studies. This analysis shows that taking selenium 100-200 mcg daily for 4 to 24 weeks improves markers of insulin resistance and reduces serum insulin levels but does not lower fasting blood glucose when compared with placebo. Selenium supplementation did not reduce total or LDL cholesterol or triglycerides but may improve HDL cholesterol (110593). However, the validity of the findings from this meta-analysis is limited by the heterogeneity of the included studies, which enrolled patients with diabetes, gestational diabetes, cardiovascular disease, heart failure, or obesity. Additionally, all studies were conducted in Iran; it is unclear if these findings are generalizable to populations in other geographic locations.
Dyslipidemia. Most research shows that oral selenium supplementation does not improve cholesterol levels. Details: A meta-analysis of 11 clinical studies in adults with dyslipidemia shows that taking selenium 50-300 mcg daily for 8-24 weeks does not increase high-density lipoprotein (HDL) cholesterol levels or decrease total or low-density lipoprotein (LDL) cholesterol levels when compared with placebo. Taking selenium might modestly improve triglyceride levels, but this improvement is unlikely to be considered clinically significant (99662). Another meta-analysis of 21 mostly small, low-quality clinical studies, some of which were included in the prior meta-analysis, shows that taking various forms of selenium may modestly decrease total cholesterol levels, but does not improve triglycerides, LDL, or HDL cholesterol when compared with placebo (110595). However, the validity of the findings from this meta-analysis is limited by the heterogeneity of the included studies, which assessed various selenium dosing regimens and enrolled healthy patients or those with various cardiovascular and non-cardiovascular conditions.
Low birth weight. Oral or intravenous selenium supplementation does not improve outcomes in low birth weight infants. Details: Low selenium levels have been documented in low birth weight infants. However, selenium supplementation, orally or intravenously, does not appear to improve most outcomes in low birth weight infants. Clinical research shows that administering selenium, either as 7-10 mcg/kg daily parenterally or 5 mcg/kg daily orally, does not improve oxygen dependency or reduce the risk of death in low birth weight infants when compared with placebo. However, supplementation decreases the incidence of sepsis by up to 33% (74288,97083).
Lung cancer. Oral selenium does not reduce lung cancer risk in most patients. Details: A meta-analysis of three large clinical trials of over 20,000 patients, including patients with resected stage I non-small-cell lung cancer, shows that taking selenium 200-400 mcg daily for up to 5 years does not reduce the risk of lung cancer when compared with control (92912,97092). A secondary analysis of one of these studies found that selenium supplementation might reduce lung cancer risk in people with selenium levels below 105 ng/mL (9798). Also, a large study in healthy Chinese patients shows no benefit of using selenium in combination with other nutrients for over 5 years when compared with control (34539).
Nonmelanoma skin cancer. Oral selenium does not reduce the risk of nonmelanoma skin cancer and has been linked to increased risk in some patients. Details: Epidemiological research has found that higher selenium intake is not associated with a reduced risk of nonmelanoma skin cancer (97085). Furthermore, clinical research shows that taking selenium orally 200 mcg daily does not reduce the risk of basal cell carcinoma when compared with control (2664,10687). In addition, some evidence shows that daily selenium supplementation might increase the risk of squamous cell carcinoma and total non-melanoma skin cancer (10687).
Prostate cancer. Oral selenium does not seem to reduce prostate cancer risk. Details: Population studies have found that higher serum or toenail selenium levels are associated with a decreased risk of prostate cancer (8734,8735,8736,92911,10263). However, clinical research does not support this finding. A meta-analysis of 5 large clinical trials of over 20,000 patients shows that selenium 200-400 mcg daily for up to 5 years does not reduce the risk of prostate cancer when compared with control (97092). A 7-14 year follow-up study of one of these trials shows there was still no reduction of prostate cancer risk (17688). Selenium has also shown no benefit when used in combination with other supplements. In a large-scale clinical study (SU.VI.MAX), taking selenium 100 mcg in combination with vitamin C, vitamin E, beta-carotene, and zinc did not reduce prostate cancer risk (14135). In 2009, the US Food and Drug Administration (FDA) approved a qualified health claim regarding selenium and prostate cancer risk, stating that it is highly unlikely that selenium supplements reduce the risk of prostate cancer (102373).
Psoriasis. Oral selenium does not seem to reduce psoriasis severity. Details: Clinical research shows that taking selenium-enriched yeast 600 mcg daily for 12 weeks, either alone or in combination with vitamin E 600 IU daily, does not reduce the severity of psoriasis when compared with placebo (74460).
Sepsis. Intravenous selenium does not appear to improve outcomes in septic adults. Details: Earlier meta-analyses of clinical trials in septic adults showed that parenteral administration of selenium, along with routine nutritional interventions, reduces the risk of mortality by 11% to 27% when compared with placebo (90347,92907,92910). However, a more recent meta-analysis, which includes a large, multi-center study of over 1000 cases, shows that parenteral selenium does not reduce mortality in septic adults at 28, 90, or 180 days when compared with placebo (99658). Enteral selenium with other nutrients has been studied for sepsis in children. Clinical research in children shows that taking enteral selenium 40-400 mcg daily with zinc, glutamine, and IV metoclopramide is no more effective than whey protein for reducing time to first episode of nosocomial infection or sepsis in the intensive care unit (ICU). However, the selenium combination treatment might reduce the risk for sepsis in immunocompromised pediatric patients (86095).

INSUFFICIENT RELIABLE EVIDENCE to RATE

Age-related cognitive decline. It is unclear if oral selenium reduces the risk of cognitive decline in older adults. Details: A cross-sectional study in elderly Americans has found that lower blood levels of selenium are associated with a greater risk of poor cognitive scores when compared with higher levels (104426).
Alcohol-related liver disease. Although there is interest in using oral selenium for alcohol-related liver disease, there is insufficient reliable information about the clinical effects of selenium for this condition.
Allergic rhinitis (hay fever). Although there is interest in using oral selenium for allergic rhinitis, there is insufficient reliable information about the clinical effects of selenium for this condition.
Arsenic poisoning. It is unclear if oral selenized yeast is beneficial for patients that were exposed to high levels of arsenic in the environment. Details: A small clinical study in Chinese people environmentally exposed to high concentrations of arsenic shows that taking selenized yeast providing 100-200 mcg of selenium daily for 14 months decreases the concentration of arsenic and symptoms of toxicity when compared with placebo (7831).
Benign prostatic hyperplasia (BPH). Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in men with BPH shows that taking selenium 240 mcg plus silymarin 570 mg daily for 6 months reduces lower urinary tract symptoms when compared with placebo (88155). Another clinical study in men with BPH shows that taking tamsulosin 0.4 mg plus a specific product containing selenium, saw palmetto, and lycopene (Profluss, Ayanda AS) daily for one year improves lower urinary tract symptoms and urodynamic parameters when compared with tamsulosin-alone (90354). It is unclear if these effects are due to selenium, other ingredients, or the combinations.
Burns. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Small clinical studies in patients with burns on 46% of their body surface suggest that taking a combination of copper 2.5-3.1 mg, selenium 315-380 mcg, and zinc 26.2-31.4 mg daily reduces the incidence of hospital-acquired pneumonia, but does not seem to improve wound healing, hospital stay, or mortality, when compared with placebo (6520,74382). Another very small clinical study in burn patients suggests that taking copper 4.5 mg, selenium 190 mcg, and zinc 40 mg daily reduces the duration of hospitalization, but does not have an effect on recovery and wound treatment requirements, when compared with standard dietary doses of these nutrients (74485).
Cancer. Selenium does not seem to reduce the risk of cancer in most people, but it might be beneficial in those with low selenium levels and in men. Details: Meta-analyses of clinical research and several clinical studies show that selenium supplementation does not reduce the incidence of cancer or cancer-related mortality when compared with control (14109,34538,74414,97078,97092). In clinical studies, selenium 100-400 mcg taken daily for 2-7.5 years with or without additional antioxidants did not reduce overall cancer risk (14109,34538,74414). However, most evidence did not assess baseline selenium levels. Other evidence suggests that selenium may have a benefit in men and in people with lower selenium levels. Epidemiological research has found that selenium intake at the recommended daily allowance (RDA) of 55 mcg or higher is associated with decreased cancer incidence and cancer mortality, especially in men (97085,103164). However, this research suggests that cancer risk was also influenced by age, body mass index, and smoking status (103164). Some clinical research also suggests that taking selenium might decrease the risk of cancer, when only men are considered (14109). An older meta-analysis of clinical research suggests that selenium was particularly beneficial in patients with lower baseline levels of selenium and in patients at high risk for cancer (90350). In 2003, the US Food and Drug Administration (FDA) approved a qualified health claim stating that consumption of selenium may produce anticarcinogenic effects and reduce the risk for certain forms of cancer. However, the FDA has determined that the evidence is limited and inconclusive (102374).
Cataracts. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: An ancillary clinical study shows that taking selenium 200 mcg daily with or without vitamin E 400 IU daily for around 5.6 years does not reduce the risk of age-related cataracts in men when compared with placebo (92902).
Cervical dysplasia. It is unclear if oral selenized yeast is beneficial for patients with cervical dysplasia of mild severity. Details: A small clinical study in patients with cervical intraepithelial neoplasia grade 1 (CIN1) shows that taking yeast containing selenium 200 mcg daily for 6 months resulted in regression of CIN1 in 88% of participants, compared with regression in only 55% of participants taking placebo (97944).
Chemotherapy-induced nephrotoxicity. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in cancer patients shows that drinking a beverage containing vitamin C, vitamin E, and selenium does not prevent cisplatin-induced nephrotoxicity when compared with a placebo beverage (74340). However, poor compliance to treatment may limit the validity of these findings.
Chronic fatigue syndrome (CFS). Although there is interest in using oral selenium for CFS, there is insufficient reliable information about the clinical effects of selenium for this condition.
Cirrhosis. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with primary biliary cirrhosis shows that taking a combination of selenium, vitamin A, vitamin C, vitamin E, methionine, and coenzyme Q10 for 12 weeks does not improve fatigue or any other disease-related symptoms when compared with placebo (34494).
Cisplatin-associated ototoxicity. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in cancer patients shows that drinking a beverage containing vitamin C, vitamin E, and selenium does not prevent cisplatin-associated hearing loss when compared with placebo beverage (74340). However, poor compliance to treatment may limit the validity of these findings.
Colorectal adenoma. It is unclear if oral selenium prevents recurrence of adenomas in the colon and rectum. Details: A large clinical study in patients with a history of colorectal adenomas shows that taking a specific selenium supplement (SelenoExcell High Selenium Yeast, Cypress Systems) 200 mcg daily for about 33 months does not reduce adenoma recurrence when compared with placebo. However, in a sub-group of patients with advanced adenomas at baseline, selenium seems to reduce risk of recurrence by 18% when compared with placebo (97091). Some research also shows that taking selenium in combination with zinc, and vitamins A, C, and E reduces adenoma recurrence when compared with placebo (92903). It is not clear any benefit is due to selenium, other nutrients, or the combination.
Congestive heart failure (CHF). Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large clinical study in elderly patients with heart failure living in Sweden shows that taking a specific selenium supplement (SelenoPrecise, Pharma Nord) 200 mcg plus a specific coenzyme Q10 supplement (Bio-Quinon, Pharma Nord) 200 mg daily for about 4 years reduces the risk of cardiovascular mortality by about 55% when compared with placebo (92904). The risk reduction seems to be most pronounced in patients with lower selenium levels (97906). Furthermore, at 10- and 12-year follow-ups, cardiovascular mortality in the treatment group continued to be 49% and 41% lower, respectively, when compared with placebo (96546,97466). It is unclear if the benefit can be attributed to selenium, coenzyme Q10, or the combination.
Coronary artery bypass graft (CABG) surgery. It is unclear if oral selenized yeast is beneficial for patients undergoing CABG surgery. Details: A small clinical study in patients undergoing CABG surgery shows that taking selenium 200 mcg daily as selenium yeast for 4 weeks improves glycemic control, lipid levels, and markers of inflammation when compared with placebo (103163). It is not known whether this influences the outcome or complications of CABG surgery.
Critical illness (trauma). Evidence on the use of intravenous selenium in critically ill patients is conflicting. Details: The most recent meta-analysis of 24 clinical trials in critically ill patients shows that intravenous selenium does not improve survival over 6 months, shorten hospital stay, or reduce intensive care unit (ICU) stay, infectious complications, development of acute kidney failure, or duration of mechanical ventilation when compared with control. Also, length of ICU stay was increased by about 4.5-fold in patients receiving selenium in doses of more than 1000 mcg daily (109086). These findings are similar to those of a meta-analysis of 21 randomized controlled trials in critically ill patients from 2016 which shows that intravenous selenium given alone or with other nutrients does not improve mortality, duration of hospital stay, or kidney function when compared with control (97090). However, another recent meta-analysis of 19 clinical trials in critically ill patients shows that intravenous selenium reduces total mortality by 14% and shortens hospital stay by about 2 days when compared with control, without affecting ICU stay, duration of mechanical ventilation, or mortality over 28 days (101345). The reasons for these discrepancies are not clear and do not seem to be completely explained by differences in doses or durations of selenium (109086). Some reasons for the discrepancies might include differing analytic methods used in meta-analyses, as well as variations in forms of selenium, concomitant treatments, and specific patient populations. One sub-analysis shows that, when limited to randomized controlled trials examining the effect of selenium supplementation in patients sustaining traumatic injury, the odds of mortality was reduced by about 26% and duration of ICU and hospital stay were modestly reduced. There was no effect on infectious complications (109090).
Dementia. It is unclear if oral selenium prevents dementia or reduces symptoms. Details: Observational research has found that taking selenium 200 mcg daily for 4 years does not decrease the incidence of dementia in men 60 years or older (93570). However, the follow-up period may not have been long enough to reliably detect the effect of selenium on the development of dementia. Also, the screening method used to detect new cases of dementia may have failed to identify individuals presenting with only the initial symptomatic stages of the disease (93570,93571).
Depression. It is unclear if oral selenium is beneficial for the treatment of prevention of depression. Details: A meta-analysis of observational research has found no difference in serum levels of selenium between patients with or without depression. In addition, serum levels of selenium do not correlate with depression scores (109091). A meta-analysis of clinical research shows that selenium supplementation, usually 100-200 mcg daily, modestly reduces symptoms of depression; however, at least one of the three studies included in this meta-analysis investigated the effects of selenium in patients with postpartum depression, specifically (109091). These meta-analyses are limited by the quality of included research and the small number of available studies.
Diabetic nephropathy. It is unclear if oral selenium alleviates diabetic nephropathy symptoms. Details: A small clinical study in patients with diabetic nephropathy shows that taking selenium (Nature Made) 200 mcg daily for 12 weeks does not improve kidney markers such as blood urea nitrogen or serum creatinine when compared with placebo (97084).
Dilated cardiomyopathy. There is limited evidence on the oral use of selenium in patients with Keshan disease and peripartum cardiomyopathy. Details: Observational research in patients with a specific type of dilated cardiomyopathy called Keshan disease and congestive heart failure has found that selenium supplementation is associated with a 61% decreased risk of cardiac death when compared with no supplementation (101346). A small clinical study in patients with peripartum cardiomyopathy and selenium deficiency shows that taking selenium 200 mcg daily for 3 months does not seem to improve heart failure symptoms or left ventricle systolic function, or prevent death, when compared with no treatment (104420).
Esophageal cancer. Limited research suggests that oral selenium does not reduce esophageal cancer risk. Details: Low quality clinical research suggests that taking selenium supplements alone or with other vitamins does not decrease the risk of esophageal cancer when compared with control (4679,12185).
Gastric cancer. Oral selenium has only been evaluated in combination with other ingredients and in a specific patient population; its effect when used alone and in other populations is unclear. Details: Population research in Chinese patients has found that high levels of selenium are associated with lower risk of gastric cancer and cancer mortality (97948). However, clinical research does not agree. A large clinical study in patients residing in China shows that taking selenium 37.5 mcg in combination with vitamin C 250 mg and vitamin E 100 IU twice daily for about 7.3 years does not reduce the risk of developing gastric cancer or precancerous gastric lesions when compared with placebo. This combination treatment was not associated with reduced gastric cancer incidence or mortality at the 14-year follow-up of this study (14447,51470). Another clinical study in healthy Chinese adults also shows that taking a combination of selenium 50 mcg, vitamin E 30 mg, and beta-carotene 15 mg daily for 5.2 years does not reduce the risk of gastric cancer when compared with control (4679). It is unclear if these findings are generalizable to populations in geographic locations other than China.
Graves' ophthalmopathy. It is unclear if oral selenium is beneficial for Graves' ophthalmopathy. Details: A small clinical trial in adults with Graves' ophthalmopathy shows that taking selenium 100 mcg twice daily for 6 months is modestly beneficial for reducing disease activity, based on signs and symptoms including pain, swelling, and redness, when compared with placebo (109085).
Hepatitis C. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with hepatitis C shows that taking a combination of selenium 200 mcg, vitamin C 500 mcg, and vitamin E 945 IU daily for 6 months does not have an effect on levels of alanine aminotransferase or viral load when compared with placebo (74377).
HIV/AIDS. It is unclear if oral selenium improves outcomes in patients with HIV. Details: Clinical trials in HIV-positive men and women, most receiving anti-retroviral therapy (ART), shows that taking selenium 200 mcg daily for up to 2 years can reduce HIV-1 viral load, increase CD4 cell counts, and lower the risk of hospitalizations when compared with placebo (15266,74314). However, not all research agrees. Two small clinical trials in HIV-positive patients taking ART shows that taking selenium 100-200 mcg daily for 6-12 months does not reduce the risk for opportunistic infections and does not increase CD4 counts when compared with control (7830,104417). Furthermore, selenium does not seem to benefit patients that are not receiving conventional ART. A large clinical study in HIV-infected pregnant patients in Tanzania with poor access to ART shows that taking selenium 200 mcg daily with prenatal vitamins until 6 months after delivery, does not improve progression of HIV nor pregnancy outcomes when compared with no selenium supplementation (74419). Another large clinical study in HIV-infected and ART-naïve patients in Botswana shows that taking selenium 200 mcg daily for 24 months does not slow HIV progression when compared with placebo (92905).
Hypertension. It is unclear if oral selenium improves blood pressure. Some evidence suggests selenium supplementation may slightly increase systolic blood pressure. Details: A meta-analysis of 5 small clinical studies in adults with various health conditions shows that taking selenium or selenium yeast 100-200 mcg/day for 6-12 weeks may increase systolic blood pressure by about 2 mmHg but does not impact diastolic blood pressure when compared with placebo (110595). However, the validity of the findings from this meta-analysis is limited by the heterogeneity of the included studies, which enrolled patients with preeclampsia, gestational diabetes, obesity, or heart failure. Additionally, all studies were conducted in Iran; it is unclear if these findings are generalizable to populations in other geographic locations.
Hyperthyroidism. It is unclear if oral selenium alleviates symptoms in patients with Graves' disease. Details: A small clinical study in patients with Graves' hyperthyroidism shows that taking sodium selenite 300 mcg daily in addition to treatment with methimazole for 24 weeks does not affect symptoms or recurrence rates when compared with placebo plus methimazole (97089). Oral selenium has also been studied in combination with other supplements. A small preliminary clinical trial in patients with newly diagnosed Graves' disease and low levels of selenium and vitamin D shows that taking selenium 100 mcg daily for 180 days along with vitamin D as cholecalciferol 7000 IU weekly for 270 days, in addition to methimazole, modestly reduces levels of serum free thyroxine and improves quality of life when compared with methimazole alone. However, taking selenium and vitamin D did not affect levels of free triiodothyronine or positive thyroid stimulating hormone (TSH) receptor antibody (109049).
Hypothyroidism. It is unclear if oral selenium improves thyroid hormone balance in elderly individuals, pregnant patients, or patients with subclinical hypothyroidism. In patients with iodine deficiency, selenium supplementation may be harmful. Details: Low selenium levels or selenium deficiency seems to reduce conversion of thyroxine (T4) to triiodothyronine (T3). However, clinical research in healthy elderly patients is conflicting. Although one study shows that taking selenium 100 mcg daily for 3 months increases conversion of T4 to T3 when compared with placebo (17508), a larger study shows that taking selenium 100-300 mcg daily for 6 months does not impact conversion of T4 to T3 when compared with placebo (17509). Additionally, taking selenium can worsen hypothyroidism in people with iodine deficiency. People who are iodine- and selenium-deficient should not receive selenium supplements without concomitant iodine. In these individuals, selenium increases conversion of T4 to T3, but the thyroid gland lacks iodine to synthesize more T4 (1664,14563,14564,14565,17508). Selenium does not have a significant effect on thyroid function when iodine intake is adequate (1664,4844). In pregnant patients with hypothyroidism, clinical research shows that taking selenium does not reduce complications such as pre-eclampsia or preterm birth. However, selenium might improve postpartum thyroid function and decrease the risk of postpartum thyroiditis (17507). Also, taking selenium 200 mcg daily during pregnancy seems to reduce the risk of developing postpartum thyroid dysfunction and permanent hypothyroidism by 41% and 42%, respectively, when compared with placebo in euthyroid pregnant patients who are positive for thyroid peroxidase antibodies (74391). Selenium supplementation has also been studied for subclinical hypothyroidism. Clinical research in females aged 18 to 50 years with or at risk for subclinical hypothyroidism in Slovakia shows that taking selenium 83 mcg daily and myo-inositol 600 mg daily for 6 months modestly reduces thyroid stimulating hormone (TSH) and thyroid auto-antibody titers when compared with baseline. Selenium and myo-inositol supplementation also reduced patient-reported hypothyroid symptoms including fatigue, menstrual cycle irregularity, and intolerance to heat or cold (110591). The interpretation of these results is limited by the lack of a control group. In addition, it is unclear if these effects are due to selenium, myo-inositol, or the combination.
Influenza. Although there is interest in using oral selenium for influenza, there is insufficient reliable information about the clinical effects of selenium for this condition.
Kidney failure. It is unclear if oral selenium is beneficial for improving lipid parameters in patients on hemodialysis. Details: Selenium levels may be low in patients undergoing chronic hemodialysis, and supplementation might be needed (1805,11053). However, clinical research in patients on hemodialysis shows that taking selenium daily for 3 months does not improve the lipid profile when compared with taking placebo (109095).
Lichen planus. It is unclear if topical or oral selenium alleviates oral lichen planus symptoms. Details: A small clinical study in patients with oral lichen planus shows that applying a selenium hydrogel (selenomethionine 14 mcg/gram) twice daily for 6 weeks seems to significantly reduce pain at a 12 week follow-up, but not immediately after use, when compared with applying topical corticosteroids and antifungal agents 2-4 times daily. Taking oral selenium 200 mcg twice daily for 6 weeks seems to be no different than the topical corticosteroids and antifungal treatment at both time points (104422).
Liver cancer. It is unclear if oral selenium reduces liver cancer risk. Details: Preliminary clinical research in China suggest that taking selenium 200 mcg daily for 2-5 years can reduce the incidence of liver cancer when compared with control (74389). The benefit of selenium on prevention of liver cancer in Western countries is unknown.
Lymphedema. It is unclear if oral selenium reduces lymphedema complications. Details: Preliminary clinical research in patients with secondary lymphedema after breast cancer surgery shows that taking a sodium selenite solution 1000 mcg daily for 1 week followed by 300 mcg daily for 2 weeks and then 200 mcg daily for a total of 15 weeks might reduce recurrence of erysipelas, a type of bacterial skin infection, when compared with placebo (15334).
Male infertility. It is unclear if oral selenium, used alone or in combination with other antioxidants, improves pregnancy or live birth rates for couples with idiopathic male infertility. Details: Meta-analyses of 2-3 clinical trials show that taking selenium, alone or in combination with other antioxidants, for 12-26 weeks modestly improves sperm count and motility when compared with placebo. However, pregnancy rates and live birth rates were only studied in one clinical trial each, with no statistical evidence of benefit (109094). Studies included in the analysis used selenium 26-200 mcg daily for 12-26 weeks, either alone or in combination with vitamin A 1 mg, vitamin C 10 mg, and vitamin E 15 mg; vitamin E 400 IU and folic acid 5 mg; lycopene 6 mg, vitamin E 400 IU, vitamin C 100 mg, zinc 25 mg, folate 0.5 mg, and garlic 1000 mg; or N-acetyl-cysteine 600 mg (74526,74493,102968,109094).
Mercury toxicity. It is unclear if oral selenium improves clearance of mercury and reduces symptoms of toxicity. Details: A small clinical trial in Chinese adults environmentally exposed to high concentrations of mercury shows that taking selenium-enriched yeast, containing selenium 100 mcg, daily for 3 months increases urinary excretion of mercury when compared with control (90351).
Muscular dystrophy. There is limited evidence on the oral use of selenium in Duchenne muscular dystrophy. Details: Preliminary clinical research suggests that supplementation with sodium selenite 1 mg daily for 6 months does not improve disease activity in patients with muscular dystrophy (74455).
Obesity. It is unclear if oral selenium is beneficial for weight reduction. Details: A small clinical study in adults with obesity shows that taking selenium 240 mcg daily and following a low-calorie diet for 3 months is no different for weight reduction when compared with following a low-calorie diet alone (104416).
Oral mucositis. It is unclear if oral selenium is beneficial for reducing oral mucositis in patients undergoing radiotherapy. Details: A small clinical study in patients with head and neck cancers shows that taking selenium 200 mcg twice daily for the duration of radiation therapy does not seem to reduce the incidence or severity of oral mucositis when compared with placebo (104421). It is unclear if other doses or routes of administration might be beneficial.
Osteoarthritis. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with osteoarthritis shows that taking a specific selenium-containing combination supplement (Selenium-ACE) does not improve most clinical symptoms when compared with placebo (74449).
Ovarian cancer. It is unclear if oral selenium reduces ovarian cancer risk. Details: Epidemiological research has found that there is no association between dietary selenium intake and the risk of developing ovarian cancer (74342).
Overall mortality. Although oral selenium does not seem to reduce overall mortality risk in most patients, it might have benefit in patients with low nutrient intake. Details: Meta-analyses of clinical research show that selenium supplementation, alone or in combination with other micronutrients, does not reduce all-cause mortality when compared with placebo (15305,90360,97078). Selenium might also not be beneficial when used in combination with non-nutrient supplements. An additional large clinical study in elderly patients in Sweden shows that taking selenium 200 mcg daily plus coenzyme Q10 100 mg twice daily for around 5 years does not reduce the risk of all-cause mortality when compared with placebo. The baseline selenium status of these patients is unclear (92904). Despite these results, some evidence suggests that selenium used with other nutrients might have benefit in patients with low nutrient intake. In a large clinical study, selenium in combination with zinc, vitamin C, vitamin E, and beta-carotene lowered all-cause mortality risk in men, but not women, when compared with control (14109). Researchers speculate that this result occurred because men have a lower intake of dietary antioxidants than women. Another large clinical study in Chinese patients with chronically low nutrient intake shows that taking selenium with beta-carotene and vitamin E decreases stroke mortality, cancer mortality, and total mortality when compared with control (2673).
Pancreatic cancer. It is unclear if oral selenium reduces pancreatic cancer risk. Details: Some epidemiological research has found that increased selenium intake is associated with a 34% lower risk of pancreatic cancer (97093). However, other observational research has found no association (101342).
Pancreatitis. Although there is interest in using oral selenium for pancreatitis, there is insufficient reliable information about the clinical effects of selenium for this condition.
Polycystic ovary syndrome (PCOS). It is unclear if oral selenium is beneficial for PCOS. Details: A small clinical study in patients with PCOS shows that taking selenium (Nature Made) 200 mcg daily for 8 weeks results in a significantly higher pregnancy rate of 19%, compared with 3% in those taking placebo. The incidences of alopecia and acne were reduced by 77% and 73%, respectively. There were also modest reductions in hirsutism severity and serum levels of high sensitivity C-reactive protein (hs-CRP) and dehydroepiandrosterone (DHEA); however, there was no effect on other hormone levels (109096). Another small clinical study in patients with PCOS undergoing in vitro fertilization shows that taking selenium yeast 200 mcg daily for 8 weeks improves measures of insulin sensitivity and reduces serum insulin and fasting blood glucose levels when compared with placebo. However, selenium supplementation does not improve the pregnancy rate or lipid parameters (110596). The effect of selenium supplementation on the live birth rate in this population is unclear. Selenium has also been studied in combination with other supplements for patients with PCOS. A small clinical study in adults with PCOS shows that taking selenium 200 mcg daily for 12 weeks, in conjunction with a combination probiotic product, modestly improves subjective scores of depression, anxiety, and stress when compared with placebo. Taking this combination also modestly reduces total testosterone levels and subjective ratings of hirsutism when compared with placebo (99659). It is not clear if these effects are due to selenium, the probiotic, or the combination.
Postpartum depression. It is unclear if oral selenium is beneficial for postpartum depression. Details: A meta-analysis of two observational studies has found that a high selenium intake is associated with a modestly reduced risk of postpartum depression. The effect of selenium supplementation on symptoms of postpartum depression is unclear. One moderate-sized clinical trial included in this publication shows that taking selenium reduces symptoms of postpartum depression (109091).
Pregnancy-induced hypertension. It is unclear if oral selenium reduces the development of hypertension during pregnancy. Details: A small clinical study in pregnant patients shows that drinking a dietary liquid containing selenium 100 mcg daily for 6-8 weeks seems to decrease the incidence of pregnancy-induced hypertension when compared with placebo (74481).
Premature rupture of membranes (PROM). It is unclear if oral selenium during pregnancy prevents PROM. Details: One clinical trial shows that taking selenium 100 mcg daily from the first trimester of pregnancy until delivery significantly reduces the incidence of PROM to 13%, compared to 34% with placebo (109097).
Radiation-induced diarrhea. It is unclear if oral selenium reduces diarrhea in patients receiving radiation therapy for cancer. Details: A small clinical study in patients with cervical or endometrial cancer shows that taking selenium 500 mcg on days of radiation therapy and 300 mcg on days without radiation therapy reduces the incidence of radiation-induced diarrhea to 20.5%, compared to 44.5% in the control group not taking selenium. This benefit appears to be more pronounced in patients receiving a larger (>1302 mL) planning target volume of radiation (90355).
Rheumatoid arthritis (RA). It is unclear if oral selenium, as selenized yeast, reduces RA symptoms. Details: A small clinical study in patients with RA suggests that taking selenized yeast, providing selenium 200 mcg, daily for 90 days does not improve objective measures of RA when compared with placebo. However, there might be small improvements in quality of life measures (9763).
Schizophrenia. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with schizophrenia shows that taking a combination of selenium (Nature Made) 200 mcg and a combination probiotic mixture (LactoCare, Zisttakhmir Company) daily for 12 weeks modestly improves general positive and negative symptoms of schizophrenia, but not positive or negative scores, when compared with placebo. There were also modest improvements in levels of high-sensitivity C-reactive protein (CRP), fasting glucose, insulin resistance, and insulin sensitivity, but not lipid parameters (109087).
Statin-induced myopathy. Small clinical studies suggest that oral selenium may not improve symptoms of myopathy in patients taking statins. Details: Small clinical studies in patients with statin-induced myopathy suggests that taking selenium (SelenoPrecise, Pharma Nord) 200 mcg daily with or without coenzyme Q10 for 3 months does not improve myopathy symptoms when compared with placebo (92908,92909).
Stroke. It is unclear if intravenous selenium improves neurological outcomes following a stroke. Details: A small clinical trial in patients with a recent first ischemic stroke shows that intravenous sodium selenite pentahydrate (Selenase, Biosyn, Arzenitmittel GmbH) 2000 mcg after admission and then 1000 mcg daily for 5 days modestly improves some, but not all, measures of neurological deficits when compared with placebo (109088). Another small clinical trial in patients with a recent ischemic stroke shows that the same intervention improves some neurological outcome measures on day 7 or at an earlier discharge, but benefits were not maintained at 3 months (109093). The effects of oral selenium on neurological outcomes following a stroke have not been investigated.
Succinylcholine-induced myalgia. It is unclear if oral selenium is beneficial for preventing succinylcholine-induced postoperative myalgia. Details: Clinical research in patients receiving succinylcholine for a sinuscopy shows that taking a single dose of selenium 200 mcg 2 hours before anesthesia induction modestly decreases the incidence of postoperative myalgia at 24 hours. In those taking selenium, 95% of patients had no postoperative myalgia, compared with 77.5% of those taking placebo. Postoperative analgesia requirements were also modestly reduced; however, there was no difference in overall pain or the incidence of muscle twitching (109089).
Thyroid cancer. It is unclear if oral selenium reduces the risk of thyroid cancer in most patients. Details: In 2009, the US Food and Drug Administration (FDA) approved a qualified health claim regarding selenium and thyroid cancer risk. This qualified health claim was based on one weak and limited study. The FDA has determined that it is highly uncertain that selenium supplements reduce the risk of thyroid cancer (102373). More recent observational research in postmenopausal individuals using data from the Women's Health Initiative has found that selenium intake at or above the recommended daily allowance from dietary sources or supplements is not associated with a decreased risk of thyroid cancer (110590).
Ulcerative colitis. Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in patients with ulcerative colitis shows that taking a liquid supplement containing a combination of selenium, fish oil, fructo-oligosaccharides, acacia, vitamin E, and vitamin C daily for 6 months does not improve disease activity scores when compared with placebo. However, taking the combination supplement seems to reduce the need for oral prednisone for symptom control (13757). The effect of selenium alone is unclear. More evidence is needed to rate selenium for these uses.

(Read more about SELENIUM)

VITAMIN C

EFFECTIVE

Vitamin C deficiency. Oral or intramuscular vitamin C is effective for preventing or treating vitamin C deficiency. Details: Administering vitamin C orally or intramuscularly prevents and treats vitamin C deficiency, including scurvy. Vitamin C administration can reverse complications of scurvy within 2 days to 3 weeks (4844). In newborns with transient tyrosinemia due to vitamin C deficiency, oral or intramuscular vitamin C can correct this condition (15).

POSSIBLY EFFECTIVE

Anemia of chronic disease. Oral vitamin C seems to improve markers of anemia in patients on hemodialysis. Details: Meta-analyses of clinical research in hemodialysis patients with anemia shows that treatment with vitamin C 200-300 mg three times weekly for 3-6 months increases hemoglobin levels by approximately 0.9 grams/dL, increases transferrin saturation by about 8%, and decreases the required recombinant human erythropoietin dose by 17 U/kg weekly when compared with standard care (83447,83475).
Atrial fibrillation. Oral and intravenous vitamin C seems to help prevent atrial fibrillation after cardiac surgeries. Details: Meta-analyses of clinical research show that taking vitamin C prior to and after cardiac surgery reduces the risk of postoperative atrial fibrillation by 27% to 53%. Most studies administered vitamin C at doses of 1-2 grams orally daily for 1-3 days prior to cardiac surgery, followed by 1-2 grams in two divided doses daily for 4-5 days after cardiac surgery. Some studies provided vitamin C intravenously at similar doses, but oral vitamin C seems to be more effective (91233,96703,96705). Despite these findings, a meta-analysis of clinical research conducted only in the U.S. does not support the benefit of vitamin C for reducing postoperative atrial fibrillation (96703). These differences may be related to lifestyle factors such as nutrition, as well as differences in hospital treatments. Vitamin C has also been studied in combination with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with evidence of benefit (90701).
Bowel preparation. Powdered vitamin C is approved for use as part of a polyethylene glycol-based bowel preparation for colonoscopy. Details: Clinical research shows that treatment with 2 liters of oral solution containing polyethylene glycol (PEG) plus vitamin C achieves a similar quality of bowel cleansing as treatment with 4 liters of PEG when administered on the evening prior to colonoscopy or when administered in a split-dose regimen. Patients given 2 liters of PEG plus vitamin C solution also have better adherence and experience fewer adverse events, such as nausea, vomiting, or abdominal bloating, compared to patients treated with 4 liters of PEG solution without vitamin C (90413,90415,90420,90424,90428). This treatment also appears to be effective and tolerable in elderly patients aged 60-79 years, including those with poor bowel habits and a high number of comorbidities (108085). Other clinical research in older adults undergoing bowel preparation for colonoscopy also shows that taking 1 liter of PEG plus vitamin C (CleanViewAL, Taejoon Pharm) results in similar quality of bowel cleansing overall and per segment with similar tolerability and adverse effects as sodium picosulfate 170 mL plus magnesium citrate or oral sulfate solution alone (111297,112476). The most common PEG plus vitamin C preparation used in clinical research is MoviPrep (Norgine BV), which contains macrogol 3350 100 grams, sodium sulfate 7.5 grams, sodium chloride 2.7 grams, potassium chloride 1 gram, vitamin C 4.7 grams, and sodium ascorbate 5.9 grams per liter of solution (90413,90415,90424). In the U.S., MoviPrep is approved by the Food and Drug Administration (FDA) for bowel preparation prior to a colonoscopy.
Cataracts. Dietary and supplemental intake of vitamin C may reduce the risk of developing cataracts. Details: Population research suggests that people with the highest total intake of vitamin C have about a 19% reduced risk of developing cataracts when compared with those with the lowest total intake, with the most benefit observed for nuclear cataracts (96711). Additionally, another observational study shows that higher supplemental intake of vitamin C over 10 years is associated with a 60% reduction in the incidence of nuclear and cortical cataracts (4208). Other population research suggests that individuals with the highest blood levels of vitamin C have a 33% lower odds of developing age-related cataract, but any benefit is limited to Asian populations (90944). An umbrella review of meta-analyses also shows that dietary intake of vitamin C is associated with a 27% lower odds of cataract development (112095). However, a prospective clinical study shows that a combination of vitamin C, vitamin E, and beta-carotene does not prevent age-related loss of vision from cataracts in well-nourished people with an average supplementation duration of 6.3 years (7304).
Common cold. Oral high-dose vitamin C might modestly shorten and reduce cold symptoms; however, taking vitamin C prophylactically does not seem to prevent the development of a cold. Details: There is substantial controversy about the effectiveness of vitamin C for treating the common cold (1969,1989,7100,9835,9836). The majority of evidence shows that taking high doses of vitamin C orally might decrease the duration of cold symptoms by 1-1.5 days in some patients (1966,1967,1968,1987,6458,7102,9832,83487). However, other studies have found no effect with doses up to 3 grams daily (9833). A meta-analysis of clinical research in healthy children and adults shows that taking vitamin C 1-4 grams daily for one week to 5 months reduces cold severity by 13%, limits absences from daily activities, and improves the duration of severe symptoms, but does not reduce the duration of mild symptoms, when compared with placebo (113665). Vitamin C has also been investigated for preventing the common cold. A meta-analysis of clinical research suggests that vitamin C supplementation decreases the incidence of cold in individuals exposed to physical stress, but not in the general population (83487). Other research suggests vitamin C may be more effective for treating cold symptoms in children than in adults. Also, there may be a dose-dependent response; doses of at least 2 grams daily seem to work better than 1 gram doses (9834). Taking vitamin C supplements prophylactically does not decrease the risk of catching a cold (1966,1967,1968,1987,3042,6458,7101,9832). Dietary intake of vitamin C also does not seem to affect the risk of getting a cold (10780).
Complex regional pain syndrome. Most research shows that taking oral vitamin C after a wrist or distal radius fracture or after orthopedic surgery seems to reduce the risk of developing complex regional pain. Details: Although some research has found no benefit in patients with distal radius (i.e. wrist) fractures (90411,96702), most clinical research shows that taking vitamin C 500 mg daily, and possibly doses of up to 1500 mg daily, for 45-50 days beginning immediately after fracture can reduce the risk of developing complex regional pain syndrome (2045,16302,96700,96706). Reasons for discrepancies are unclear but might relate to differences in diagnostic criteria for complex regional pain syndrome (96702). Research in patients undergoing orthopedic surgery has also shown benefit with the use of vitamin C for the prevention of complex regional pain syndrome (90422,108076,108087). One meta-analysis of clinical research in patients undergoing wrist, foot, or ankle surgery shows that taking vitamin C 500-1000 mg for 42-50 days following surgery reduces the rate of complex regional pain syndrome, and may improve pain following ankle or foot surgery, when compared with placebo (108076). The validity of these findings is limited by the high heterogeneity of included trials. Another meta-analysis of clinical research in patients undergoing orthopedic surgery (i.e. wrist, knee, ankle, foot, lumbar, rotator cuff) suggests that oral and intravenous vitamin C may have similar effectiveness; however, this evidence is low quality (108087).
Exercise-induced respiratory infections. High-dose oral vitamin C seems to reduce the risk of respiratory infections associated with strenuous exercise. Details: Some preliminary clinical research suggests that prophylactic use of vitamin C in doses of 600 mg to 1 gram daily for 3-8 weeks before heavy physical exercise, such as a marathon, might prevent upper respiratory infections that sometimes follow heavy exercise (9831,83370). More recently, high doses of vitamin C have been studied. A large clinical study in army recruits undergoing basic military training shows that taking vitamin C 6 grams daily for one month reduces the odds of getting a cold by 20% when compared with placebo (102975).
Hypercholesterolemia. Oral vitamin C seems to reduce lipid levels in patients with hypercholesterolemia. Details: A meta-analysis of clinical research in patients with hypercholesterolemia shows that taking vitamin C 500 mg daily for at least 4 weeks reduces low-density lipoprotein (LDL) cholesterol by about 8 mg/dL and reduces triglycerides by about 20 mg/dL when compared with control (83445).
Hypertension. Oral vitamin C seems to modestly reduce blood pressure in patients with hypertension, but some evidence is conflicting. Details: Vitamin C seems to modestly reduce systolic blood pressure (SBP), without meaningful effects on diastolic blood pressure (DBP) (2044,9822,13162,83483,102974). A meta-analysis of 13 clinical trials in patients with hypertension, with or without other comorbidities, shows that taking a median dose of vitamin C 500 mg daily for 8 weeks reduces SBP but not DBP by about 5 mmHg. Some of the studies used vitamin C in combination with other supplements, such as vitamin E and magnesium. When studies assessing vitamin C alone were analyzed, the magnitude of reduction in SBP decreased (83483). A newer meta-analysis of small clinical studies in patients with essential hypertension shows that taking vitamin C 200 mg or more daily reduces SBP by about 4 mmHg and DBP by about 2 mmHg (102974). However, this newer analysis omitted numerous relevant studies and included studies with normotensive patients and those without an adequate control, limiting the validity of its findings. In contrast, a network meta-analysis of small, low-quality clinical studies comparing five different vitamins in adults with essential hypertension shows that vitamin C does not reduce SBP, DBP, mean 24-hour SBP, mean 24-hour DBP, or heart rate when compared with placebo and when indirectly compared with vitamin B2, vitamin D, vitamin E, and folic acid. However, the included studies were of low quality and high heterogeneity, particularly in dosing, limiting the validity of the results (113668).
Laser skin resurfacing. Topical vitamin C seems to reduce erythema occurring after cosmetic laser skin resurfacing procedures intended to reduce scars and wrinkles. Details: There is some evidence that an aqueous formulation of topical vitamin C can decrease the degree and duration of erythema following cutaneous carbon dioxide laser resurfacing for scar and wrinkle removal (1959).
Lead toxicity. Dietary vitamin C seems to lower concentrations of lead in the blood. Details: Observational research has found that consuming more vitamin C from dietary sources is associated with lower blood concentrations of lead. People who consumed at least 340 mg of vitamin C daily as part of the diet had lower blood lead levels than those who consumed less than 100 mg vitamin C daily (3097,3098,3099).
Nitrate tolerance. Oral vitamin C might prevent nitrate tolerance in some patients. Details: Small clinical studies show that taking vitamin C orally seems to prevent the development of nitrate tolerance in patients taking sublingual nitroglycerin. There is some evidence that short-term vitamin C supplementation can prevent tolerance to the vasodilatory effects of nitrates (1441,1961).
Postoperative pain. Oral or intravenous vitamin C might prevent acute postoperative pain following certain surgeries. It is unclear if vitamin C reduces chronic postoperative pain. Details: A meta-analysis of 7 small clinical studies in adults undergoing elective surgery shows that receiving perioperative vitamin C, either as 1 gram orally, 2-3 grams intravenously, or 50 mg/kg intravenously, modestly reduces acute pain and opioid requirements for up to 24 hours when compared with control (105457). Most surgeries were laparoscopic and included cholecystectomy, colectomy, hysterectomy; two non-laparoscopic surgeries included uvulopalatopharyngoplasty with tonsillectomy and major abdominal surgery (90418,99840,105457). A meta-analysis of clinical trials in adults undergoing noncardiac surgery (i.e., orthopedic, abdominal, gynecologic, kidney transplantation) shows that administering perioperative vitamin C, either orally or intravenously, reduces postoperative intravenous morphine requirements at 2, 24, and 48 hours after surgery and improves pain scores at 2, 6, and 24 hours after surgery when compared with placebo. The dose of vitamin C did not appear to impact outcomes. However, when only laparoscopic surgeries are included, perioperative vitamin C does not improve pain or morphine use when compared with placebo (108087). A moderate-sized clinical study in adults undergoing transurethral resection of a bladder tumor under general anesthesia shows that administering intravenous vitamin C 1 gram after induction of anesthesia reduces the incidence and severity of catheter-related bladder discomfort immediately after surgery and at 1 and 2 hours postoperatively, but not 6 hours, when compared with placebo. However, vitamin C does not reduce postoperative pain scores or analgesic requirements when compared with placebo (111645). For dental surgery, a small observational study in adults undergoing surgery for wisdom tooth extraction shows that taking vitamin C 500 mg three times daily for 7 days in addition to standard treatment reduces pain 24, 48, and 72 hours after surgery when compared with control (113664). Further research is needed to determine the effects of vitamin C for acute postoperative pain. Vitamin C has also been evaluated for reducing chronic pain after surgery. Clinical research in patients undergoing surgery for foot or ankle trauma shows that taking vitamin C 500 mg orally twice daily postoperatively for 6 weeks reduces pain scores when compared with placebo at 2 weeks and 6 weeks. The mean total amount of diclofenac used for pain relief over the 6-week period is also reduced, from 5.7 grams with placebo to 3.4 grams with vitamin C (102131).
Wrinkled skin. Topical vitamin C might reduce the appearance of existing wrinkles. Details: Topical preparations containing vitamin C seem to improve the appearance of wrinkled skin. Some evidence shows that vitamin C 3% applied for 12 weeks might reduce facial wrinkles (14008). A small clinical study shows that applying a dissolving microneedle patch containing vitamin C 5.6% every 4 days for 12 weeks to crow's feet on one side of the face reduces wrinkles when compared to control treatment applied on the other side of the face (98780). Other clinical research in females aged 30-60 years shows that applying an oil-soluble cream containing the vitamin C derivative tetra-isopalmitoyl ascorbic acid 1%, 2%, or 3% to the periorbital area twice daily for 8 weeks reduces visual wrinkle grading when compared with placebo. A dose analysis shows greater improvements in wrinkle parameters, average wrinkle depth, and mean depth with the lower concentration, while greater improvements in maximum roughness and maximum depth are observed with the higher concentration (108072). This study only included individuals defined as having Fitzpatrick skin type III or IV; it effects on other skin types is unclear. Preparations containing vitamin C in combination with other ingredients have also been investigated. A small low-quality trial in females with moderately photodamaged and hyperpigmented facial skin shows that applying a moisturizer with vitamin C 30%, vitamin E, and coenzyme Q10 once daily in the morning, along with applying retinol 0.5% once daily or once every other day for 12 weeks, seems to improve skin tone, photodamage, and wrinkles when compared to baseline (99085). In another small trial, a topical preparation containing vitamin C 10% as L-ascorbic acid along with acetyl tyrosine, zinc sulfate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) applied to photo-aged facial skin for 3 months improves fine and coarse wrinkling, yellowing and sallowness, roughness, and skin tone when compared with placebo (6155). It is unclear if the beneficial effects of these products are due to vitamin C, other ingredients, or the combination.

POSSIBLY INEFFECTIVE

Acute bronchitis. Oral vitamin C doesn't seem to improve symptoms of acute bronchitis. Details: A clinical study in adults with acute bronchitis shows that taking vitamin C orally 500 mg on day 1, then 250 mg on days 2 through 5 (similar to an azithromycin regimen) doesn't seem to have any effect on quality of life or bronchitis duration when compared with azithromycin (9827).
Asthma. Oral vitamin C doesn't seem to prevent asthma or improve lung function. Details: Although some observational research has found that some patients with asthma might have lower serum vitamin C levels (5873), other observational research found that increased dietary vitamin C intake is not associated with a reduced risk of asthma or improved lung function (15006,34567). In addition, clinical research shows that supplemental intake of vitamin C does not reduce asthma symptoms, improve lung function, or reduce the use of inhaled steroids in asthma patients (90409).
Atherosclerosis. Oral vitamin C does not seem to reduce the progression of atherosclerosis. Details: A clinical study shows that taking a specific combination product containing slow-release vitamin C 250 mg and vitamin E 136 IU (CellaVie, Ferrosan A/S) twice daily modestly slows the 3-year progression of atherosclerosis of the carotid artery in males, but not females. This result persisted at a 6-year follow-up of this study (1918,10473). However, when this form of vitamin C is used alone, it does not slow the 3-year progression of atherosclerosis of the carotid artery (1918).
Bladder cancer. Oral vitamin C does not reduce the risk of bladder cancer or mortality from bladder cancer. Details: Epidemiological research has found that supplemental vitamin C intake is not associated with mortality rate in patients with bladder cancer (9839). A secondary analysis of a large clinical trial, the Physicians' Health Study II, in healthy men aged at least 50 years also shows that taking vitamin C 500 mg daily alone or with vitamin E 400 IU daily for up to 10 years does not reduce the risk of developing bladder cancer or bladder cancer-related deaths when compared with placebo (90097).
Cardiovascular disease (CVD). Oral vitamin C does not seem to be beneficial for either primary or secondary CVD prevention. Details: Vitamin C does not seem to be beneficial for primary prevention of CVD. Some population research has found that higher supplemental vitamin C or dietary vitamin C has been associated with a reduced risk of developing CVD (10358,14108,109779), while other observational research has found no benefit (34566,10358,14108). However, meta-analyses of clinical research in healthy patients show that vitamin C supplementation does not prevent CVD or coronary heart disease when compared with control (97308,104025). In 2004, the American Heart Association stated that current evidence does not justify use of antioxidants such as vitamin C for reducing the risk of CVD (12142). Evidence is also negative for secondary prevention in people with coronary heart disease. Population studies have found that higher serum vitamin C was associated with no effect or decreased CVD mortality from CVD (3910,5878). A meta-analysis of two large clinical trials shows that vitamin C supplementation does not reduce CVD events or CVD mortality when compared with control (97308).
Colorectal cancer. Oral vitamin C does not seem to prevent colorectal cancer. Details: Population research has found that dietary vitamin C intake is not associated with a reduced risk of developing colon cancer. When total vitamin C intake from food and supplements is considered, there is a modest association (34600). However, most clinical trials show that supplemental vitamin C, alone or along with other antioxidants, does not reduce the risk of colorectal cancer development, colorectal cancer or adenoma recurrence, or colorectal cancer-related mortality (34580,34581,34594,90097,90089,92903).
Fetal and premature infant mortality. Oral vitamin C does not seem to prevent neonatal death. Details: Meta-analyses of clinical research show that taking vitamin C alone or with other supplements does not reduce the risk of neonatal death (83472,96707).
Fractures. Oral vitamin C does not seem to improve fracture healing. Details: Clinical research shows that taking vitamin C 500 mg daily for 50 days following an acute distal radial fracture does not improve physical function, symptoms, or healing rates when compared with placebo (90411).
Helicobacter pylori. Oral vitamin C does not seem to improve eradication of H. pylori. Details: Most clinical research shows that treatment with vitamin C, alone or in combination with vitamin E, does not improve the eradication rate of H. pylori when taken with a standard eradication regimen when compared with the eradication regimen alone (83476,90094).
Hereditary motor and sensory neuropathy. Oral vitamin C does not seem to improve neuropathy in these patients. Details: In a meta-analysis of five studies in patients with Charcot-Marie-Tooth disease type 1A, taking vitamin C 1-4 grams orally daily for 1 year did not improve neuropathy when compared with placebo (99084). Continuing vitamin C 4 grams daily for 2 years also does not improve neuropathy in these patients (90419).
Interferon-related retinopathy. Oral vitamin C does not seem to improve retinopathy associated with interferon therapy. Details: A small clinical study in patients with chronic hepatitis C receiving interferon therapy shows that taking vitamin C 600 daily orally does not seem to reduce the risk of retinopathy from interferon therapy when compared with control (10355).
Leukemia. Oral vitamin C does not seem to reduce the risk of leukemia or mortality from leukemia. Details: A large clinical trial in men aged at least 50 years shows that taking vitamin C 500 mg daily, alone or along with vitamin E 400 IU daily, for up to 10 years does not reduce the risk of developing leukemia or leukemia-related deaths when compared with placebo (90097).
Low birth weight. Oral vitamin C does not seem to reduce the risk of infants being born with a low birth weight. Details: Meta-analyses of clinical research show that maternal use of oral vitamin C alone or with other supplements does not reduce the risk of giving birth to infants with low birth weight when compared with control (83450,83472).
Lung cancer. Oral vitamin C does not seem to reduce the risk of lung cancer. Details: Two meta-analyses of clinical research suggest that taking vitamin C, alone or in combination with vitamin E, does not reduce the incidence of lung cancer or lung cancer-related mortality (34528,34632). Also, a clinical study in females shows that taking supplemental vitamin C 500 mg daily, with or without vitamin E and beta carotene, is associated with an INCREASED risk of lung cancer when compared with placebo (34580). However, another large epidemiological cancer screening trial with a mean follow-up of over 12 years suggests that moderate dietary intake of vitamin C around 500 mg daily is protective against lung cancer, but higher doses of vitamin C might increase the risk of lung cancer (112096).
Melanoma. Oral vitamin C does not seem to reduce the risk of melanoma. Details: Clinical research shows that taking vitamin C 500 mg daily, alone or along with vitamin E 400 IU daily, for up to 10 years does not reduce the risk of developing melanoma or melanoma-related deaths when compared with placebo in men aged at least 50 years (90097).
Miscarriage. Oral vitamin C does not seem to reduce the risk of miscarriage. Details: A meta-analysis of clinical research shows that taking vitamin C alone or with other supplements does not reduce the risk of miscarriage when compared with control (94820).
Overall mortality. Oral vitamin C does not reduce overall mortality. Details: Although population research suggests that higher dietary intake and higher plasma vitamin C levels are associated with a reduced risk of mortality from all causes (3910,109779), vitamin C supplementation does not seem to affect overall mortality. Meta-analyses of clinical research show that taking vitamin C supplements does not reduce overall mortality when compared with control (34622,111641). Clinical studies of vitamin C used in combination with vitamin E, beta carotene, and/or selenium and zinc, also show no benefit for overall mortality (9817,14109).
Pancreatic cancer. Oral vitamin C does not seem to prevent pancreatic cancer. Details: Observational research has found that increased dietary vitamin C intake is associated with up to a 30% reduced risk of pancreatic cancer (99083,99086). However, clinical research shows that supplemental vitamin C 500 mg daily does not reduce the risk of pancreatic cancer in females (34580). Also, taking vitamin C in combination with beta-carotene plus vitamin E does not reduce the risk of pancreatic cancer (12185,34581).
Pre-eclampsia. Oral vitamin C does not seem to prevent pre-eclampsia. Details: Despite some early positive research in high-risk pregnancies, the majority of meta-analyses and clinical studies show that taking vitamin C alone or with vitamin E or other supplements does not reduce the risk of pre-eclampsia when compared with control. There is even some concern that vitamin C supplementation may increase the risk of gestational hypertension (3236,83450,83472,83474,96707).
Preterm labor. Oral vitamin C does not seem to prevent preterm labor. Details: Meta-analyses of clinical research show that taking vitamin C alone or with other supplements does not reduce the risk of preterm labor when compared with control (83450,83472,96707).
Prostate cancer. Oral vitamin C does not seem to prevent prostate cancer. Details: A large-scale clinical study (The SU.VI.MAX study) shows that a combination of vitamin C 120 mg, vitamin E (alpha-tocopherol) 30 mg, beta-carotene 6 mg, selenium 100 mcg, and zinc 20 mg, taken daily for an average of 8 years, does not reduce the risk of prostate cancer overall. However, it might reduce the risk of prostate cancer in those who have normal PSA levels. It does not seem to be beneficial for reducing the risk of prostate cancer in patients with PSA levels above 3 mcg/L (14135). Another large scale study (Physician's Health Study II) shows that taking vitamin C 500 mg daily for an average of 8 years does not significantly reduce the risk of prostate cancer when compared with placebo (16708). Similarly, results from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial seem to show that supplemental or dietary intake of vitamin C does not reduce the risk of prostate cancer when compared to individuals not taking vitamin C (14124).
Radiation dermatitis. Topical vitamin C does not seem to prevent radiation dermatitis in cancer patients. Details: A small clinical study shows that applying a 10% vitamin C solution does not appear to protect from radiation dermatitis when applied to the scalps of patients treated with radiation for intracranial tumors (789).
Small for gestational age (SGA). Oral vitamin C does not seem to reduce SGA. Details: Meta-analyses of clinical research show that taking vitamin C alone or with other supplements does not reduce the risk of small for gestational age birth when compared with control (83450,83472).
Stillbirth. Oral vitamin C does not seem to prevent stillbirth. Details: Meta-analyses of clinical research show that maternal use of vitamin C alone or with other supplements does not reduce the risk of stillbirth when compared with control (83472,96707).

LIKELY INEFFECTIVE

Coronavirus disease 2019 (COVID-19). Oral vitamin C, even at high doses, does not seem to speed recovery from COVID-19 in non-hospitalized patients. Most studies show that oral or intravenous vitamin C given to patients hospitalized with COVID-19 does not improve organ function or survival, but the evidence is conflicting. It is unclear whether vitamin C is beneficial for long COVID. Details: A clinical study in adult outpatients with confirmed COVID-19 shows that taking oral vitamin C (ascorbic acid) 8000 mg in 2-3 divided doses daily, alone or with zinc gluconate 50 mg daily, for 10 days does not reduce symptom severity when compared with standard care (104450). The study was terminated prior to complete enrollment due to futility and apparent lack of effect from vitamin C and/or zinc supplementation. Limitations of this study include a lack of placebo control and blinding. Additionally, this study has been criticized for methodologic concerns (106624). Another small clinical trial in adult outpatients with confirmed COVID-19 shows that taking vitamin C 1000 mg daily for 14 days does not improve symptoms or quality of life when compared with placebo (109462). Vitamin C has also been evaluated in patients hospitalized with COVID-19. A very large analysis of two multinational clinical studies in critical and non-critical adults hospitalized with COVID-19 shows that administering intravenous vitamin C 50 mg/kg every 6 hours for 96 hours does not improve organ support-free days or survival and has a high probability of futility and worsened outcomes when compared with placebo (113666). Individual prospective and retrospective studies in critically ill patients hospitalized with COVID-19 in various countries have found that administering vitamin C, either enterally as 500-1000 mg daily or intravenously as 8-24 grams daily or 50 mg/kg daily, does not significantly reduce in-hospital or short-term mortality, hospital length of stay, or end-organ failure when compared with control groups receiving standard care alone. Additionally, all but one study found no change in the need for mechanical ventilation (105458,105465,106937,106938,108075,108079,108081). However, a meta-analysis and some small individual studies have found that vitamin C is modestly beneficial for patients hospitalized with COVID-19. A meta-analysis of 10 clinical trials and 9 observational studies in patients hospitalized with COVID-19 shows that receiving oral or intravenous vitamin C daily reduces the odds of in-hospital mortality by 41% when compared with control. When only clinical trials were considered, the odds of in-hospital mortality were decreased by 56%; however, this reduction was only identified in studies using vitamin C 10 grams daily or less. Conversely, supplementation with vitamin C increased the length of intensive care unit (ICU) stay by nearly 2 days and did not impact length of hospital stay or reduce the need for mechanical ventilation, liver injury, or cardiac injury (109955). Additionally, a small study found a small improvement in survival when compared with standard care; however, the overall survival rate in this study was low (108075). Another clinical study in patients hospitalized in Turkey with COVID-19 shows that adding high-dose intravenous sodium ascorbate 50 mg/kg to a treatment regimen of hydroxychloroquine, azithromycin, and zinc may improve recovery time, with 57% and 39% of patients achieving total recovery at day 15 in the vitamin C and control groups, respectively (108071). However, the validity of this trial is limited due to unclear reporting. Additionally, these small studies were likely underpowered to detect differences between the vitamin C and control groups. Vitamin C has also been evaluated in combination with other ingredients in patients with long COVID. Preliminary clinical research in adults with long COVID and persistent fatigue shows that taking a specific combination product containing vitamin C 500 mg and L-arginine 1.66 grams (Bioarginina C, Farmacetici Damor) for 28 days increases 6-minute walk test distance by 10% and reduces self-reported fatigue when compared with placebo (110390). However, it is unclear whether these effects are due to vitamin C, L-arginine, or the combination.
Sepsis. Intravenous vitamin C, alone or in combination with thiamine and/or hydrocortisone, does not prevent organ failure, reduce intensive care or hospital length of stay, or reduce mortality in sepsis or septic shock. Details: Observational research suggests that patients with septic shock are more likely to have low plasma levels of vitamin C (100317). However, two randomized clinical trials in patients with sepsis show no benefit with intravenous vitamin C, with or without thiamine, for improving organ function and preventing organ failure when compared with control treatment (102130,104027). A clinical study in patients with septic shock shows that administering an intravenous bolus of vitamin C 1000 mg followed by a continuous infusion of 250 mg/hour for 96 hours, starting within 24 hours of vasopressor initiation, does not improve 28-day or intensive care unit (ICU) mortality when compared with placebo. A subgroup analysis shows that the addition of corticosteroids does not affect outcomes in either group (108078). This study may have been inadequately powered to detect a difference between groups. Also, a larger clinical trial in adults with sepsis receiving vasopressor therapy in the ICU shows that intravenous administration of vitamin C 50 mg/kg every 6 hours for up to 4 days increases the risk of death or persistent organ dysfunction at day 28 by 14% to 21% when compared with placebo. There were no differences in mortality at 6 months (109459,111643). Vitamin C has also been frequently studied in patients with sepsis and septic shock in a specific combination regimen (HAT therapy) which includes intravenous vitamin C 1.5-2 grams with hydrocortisone 50 mg every 6 hours and thiamine 200 mg every 12 hours. While some retrospective research has found HAT therapy to be beneficial in sepsis (100315,102980), high quality, prospective clinical research has not confirmed these findings (105447,106620,109956). Several meta-analyses of randomized controlled trials and small clinical studies in patients with sepsis or septic shock show that intravenous vitamin C, either alone, as a component of HAT therapy, or in combination with thiamine, does not reduce short- or long-term mortality, ICU or hospital length of stay, kidney injury, or duration of mechanical ventilation, but modestly improves duration of vasopressor use and procalcitonin clearance, when compared with placebo or standard care. These analyses also show mixed results with respect to improvement in sequential organ failure assessment (SOFA) scores within 72 hours (105447,106620,106935,108073,109460,111298,111300,111301,111642,112479). Most studies included in the analyses administered HAT therapy for 2-10 days and compared it with normal saline control or with hydrocortisone alone (102129,102998,104027,104028,104032,105446). Although some subgroup analyses suggests that intravenous vitamin C alone in patients with sepsis may improve short-term mortality (106620,111298), other meta-analyses have not shown this benefit in subgroup analyses (111300). In addition, meta-analyses have identified significant publication bias (111298,111300). Long-term follow up from a study in patients with sepsis-induced respiratory and/or cardiovascular dysfunction shows that receiving HAT therapy does not improve cognitive, psychological, or functional status after 6 months and, for some domains, HAT therapy was worse when compared with placebo (111299). Studies evaluating intravenous vitamin C, either alone, as a component of HAT therapy, or in combination with thiamine, in mixed critically ill populations have also shown mixed findings. Four meta-analyses of randomized controlled trials and observational studies show that intravenous vitamin C does not have a significant effect on the length of hospital stay, mortality at 1 month, ICU mortality, use of invasive ventilation, use of renal replacement therapy, organ function, or incidence of kidney injury when compared with placebo or standard care. The meta-analyses reach conflicting conclusions on whether intravenous vitamin C reduces the risk of in-hospital mortality, 30-day mortality, and the duration of ICU stay. When only data from low risk-of-bias clinical trials are considered, the effects of intravenous vitamin C on mortality at any point are no longer significant (106933,106934,109957,113663). However, a subgroup analysis in one of these analyses suggests that intravenous vitamin C as monotherapy, or in doses of at least 10 grams daily, may improve overall mortality (106934). Vitamin C also does not appear to benefit complications from sepsis, such as vasoplegic shock. A small clinical study in adults in the ICU with vasoplegic shock mostly secondary to sepsis and requiring moderate vasopressor support shows that administering intravenous vitamin C as sodium ascorbate 1.5 grams every 6 hours for 5 days or until cessation of vasoactive therapy does not reduce the duration of vasopressors, vasopressor dose, hospital or ICU length of stay, or mortality outcomes when compared with placebo (112475).

INSUFFICIENT RELIABLE EVIDENCE to RATE

Atrophic acne scars. It is unclear if applying topical vitamin C after microblading improves atrophic acne scars. Details: A clinical study in adults with mild to severe atrophic acne scarring shows that applying a serum containing vitamin C 17% to the face after a once-monthly home microblade treatment for 4 months improves the appearance of acne scars at month 5 when compared with baseline (108086). Although this study enrolled a control group that used topical insulin in place of vitamin C, no between-group statistical comparisons were conducted, limiting the validity of this study.
Age-related macular degeneration (AMD). It is unclear if dietary vitamin C or oral vitamin C taken in combination with other ingredients prevents AMD. Details: An umbrella review of meta-analyses shows that increased dietary intake of vitamin C is associated with 21% higher odds of developing AMD (112095). A population study suggests that vitamin C intake is associated with increased odds of developing age-related maculopathy (9823). However, other population studies have found no association between dietary or supplemental vitamin C intake and the risk of developing AMD (14007,14257). When taken in combination with other ingredients, most clinical and population research shows that taking vitamin C 500 mg along with other antioxidants such as vitamin E 400 IU, beta-carotene 15 mg, and/or elemental zinc 80 mg reduces the risk of visual acuity loss by 23% to 27%, progression to advanced AMD at 5 years by 25% to 32%, and AMD overall (7303,7304,11326,14257,90069). The antioxidant plus zinc combination seems to reduce the risk of progression to advanced AMD in these patients more than taking the antioxidants without zinc (7303,90069). More evidence is needed to determine what role, if any, vitamin C intake has on the risk of developing AMD.
Aging skin. Topical vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in females aged 30-65 years shows that applying a specific liquid (Antioxidant and Collagen Booster Serum, Max Biocare Pty Ltd.) containing vitamin C 20%, red raspberry leaf cell culture extract 0.0005%, and vitamin E 1% to the face nightly for 8 weeks, in addition to regular facial skin products, improves skin color, elasticity, radiance, smoothness, and appearance of wrinkles when compared with regular facial skin products alone (102355).
Albuminuria. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study shows that taking vitamin C 1250 mg plus vitamin E 680 IU daily for 4 weeks can reduce the excretion of albumin by about 19% when compared with placebo in patients with type 2 diabetes (10434).
Allergic rhinitis (hay fever). It is unclear if oral vitamin C is beneficial in patients with hay fever. Details: Epidemiological research has found that higher vitamin C plasma levels are not associated with a decreased risk of allergic rhinitis (15200). However, clinical research shows that some forms of vitamin C might help. In one small clinical study, intranasal vitamin C administered three times daily for 2 weeks reduces nasal secretions, nasal blockage, and edema in up to 74% of patients with perennial allergic rhinitis (15201). Another small clinical study in patients with seasonal allergic rhinitis shows that taking a single oral dose of vitamin C 2 grams reduces bronchial responsiveness to histamine at one hour after ingestion (15202). However, in another small study in patients with seasonal allergic rhinitis taking vitamin C orally in doses up to 4 grams daily for 3 days does not appear to suppress cutaneous or nasal response to histamine when compared to placebo (15203).
Alzheimer disease. It is unclear if dietary vitamin C helps to prevent this condition. Details: Most epidemiological research has found that dietary intake of vitamin C is associated with a 17% reduced risk of developing Alzheimer disease (4636,9824,10131,13165,90082).
Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). It is unclear if oral vitamin C helps to prevent ALS. Details: Observational research has found that increased dietary or supplemental intake of vitamin C is not associated with risk of developing ALS (90412).
Anthracycline cardiotoxicity. Although there is interest in using oral vitamin C for anthracycline-induced cardiac toxicity, there is insufficient reliable information about the clinical effects of vitamin C for this condition.
Aspirin-associated gastric damage. It is unclear if oral vitamin C helps to prevent gastric damage caused by aspirin. Details: Some clinical research shows that vitamin C 480 mg might prevent gastric damage associated with taking aspirin 400 mg by decreasing blood loss and preventing decreased gastric blood flow (10357). However, a small clinical study in healthy patients shows that taking vitamin C 500 mg as ascorbic acid with aspirin 600 mg actually increases gastrointestinal permeability to a greater extent than either ingredient taken alone (98781).
Athletic performance. It is unclear if oral vitamin C improves athletic performance. Details: Although some small preliminary clinical studies suggest that vitamin C might improve certain biomarkers during exercise (82922), a meta-analysis of small clinical trials in older and younger adults shows that taking vitamin C 500-1000 mg daily, with or without vitamin E, does not improve endurance, lean mass, or muscle strength when compared with placebo (102973). A more recent, small clinical study in recreationally trained males shows that taking vitamin C 1000 mg and vitamin E (as alpha-tocopherol) 235 mg daily for 10 weeks while participating in a resistance training program does not improve measures of muscle strength when compared with placebo (109959).
Atopic disease. It is unclear if dietary vitamin C helps to prevent atopic disease. Details: Population research has found that higher intake of vitamin C is not associated with a reduced risk of eczema, wheeze, IgE-mediated food allergy, or allergic sensitization (90098).
Attention deficit-hyperactivity disorder (ADHD). Small clinical studies suggest that high-dose oral vitamin C may not improve symptoms in patients with ADHD. Details: Some research suggests that taking megadose vitamins, including vitamin C, does not improve ADHD symptoms (9957,9958,9959). However, other preliminary clinical research shows that taking 25 mg of vitamin C in combination with flaxseed oil providing alpha-linolenic acid 200 mg twice daily might improve measures of attention, impulsivity, restlessness, and self-control in children with ADHD when compared with baseline (14443). It is not clear if these effects are due to vitamin C, flaxseed oil, or the combination.
Autism spectrum disorder. It is unclear if oral vitamin C is beneficial in patients with autism spectrum disorder. Details: One small clinical study shows that taking vitamin C 8 grams per 70 kg daily for 10 weeks modestly reduces autism symptom severity in school children when compared with placebo (83604).
Bleeding. It is unclear if intravenous vitamin C can reduce bleeding after total abdominal hysterectomy. Details: A small clinical study in patients undergoing total abdominal hysterectomy shows that administration of intravenous vitamin C 1 gram the night before surgery and 1 gram during surgery reduces postoperative hemorrhage volume by around 40 mL when compared with placebo (109465).
Brain tumor. It is unclear if oral vitamin C helps to prevent brain tumors. Details: Population research has found that vitamin C intake is associated with a 14% reduced risk of glioma. This risk reduction was more prevalent in America compared to other geographic locations (98782).
Breast cancer. It is unclear if oral vitamin C helps to prevent breast cancer, its recurrence, or breast cancer-related mortality. Details: Some epidemiological research has found that dietary vitamin C is associated with a reduced risk of breast cancer (1444,10823,10824). However, other epidemiological research has found no association with dietary or supplemental vitamin C (10825,10826,108080). One cohort study found no association between breast cancer risk and total, dietary, or supplemental vitamin C, regardless of dose, treatment duration, or formulation (single ingredient or combination product). Additionally, hormone and menopausal status did not appear to impact risk. Vitamin C intake might be associated with a reduced risk in individuals with a family history of breast cancer in first-degree relatives (108080). In patients with breast cancer, supplemental or dietary intake of vitamin C might be associated with a reduced risk of mortality. A meta-analysis of results from population research shows that vitamin C supplementation following breast cancer diagnosis is associated with a 15% lower risk of breast cancer-related mortality when compared with no supplementation (90416). A large, observational study in patients with breast cancer undergoing radiation therapy has found that vitamin C supplementation does not reduce the risk of breast cancer recurrence over a period of 5 years when compared with no supplementation. Although the vitamin C group had notably less aggressive tumor types, recurrence-free survival was similar in both vitamin C and control groups (108082). The validity of these findings is limited due to unknown doses of vitamin C and the inclusion of various breast cancer subtypes.
Burns. Small studies suggest that intravenous vitamin C may modestly improve symptoms in patients with severe burns. Details: A small clinical study in patients with severe burns shows that administering vitamin C intravenously (IV) 66 mg/kg hourly over 24 hours, as part of fluid resuscitation using lactated ringer solution, reduces wound edema and the volume of fluid needed when compared with fluid resuscitation alone (83145). A retrospective review of adults hospitalized with severe burns has found that those who receive a continuous IV infusion of at least 10 grams of vitamin C within 2 days of admission have an in-hospital mortality rate of 46%, compared with 58% for those who do not receive vitamin C (102128).
Cancer. It is unclear if oral or intravenous vitamin C helps to prevent cancer or cancer-related mortality. Details: Some population research has found that DIETARY intake of vitamin C is linked with a lower risk of cancer and cancer-related mortality (3910,5878,10819,109779). However, clinical research shows that taking vitamin C SUPPLEMENTS does not reduce the risk for cancer (10819,14109,34580,90097). In people with cancer, although some clinical research has shown that taking high-dose vitamin C supplements can improve survival rates (9809,96704), other clinical research has not shown this benefit (4842,4843). In 2003, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that some scientific evidence suggests that antioxidant vitamins, such as vitamin C, may reduce the risk of certain forms of cancer. However, the FDA has determined that there is little scientific evidence supporting this claim (102334). Preliminary clinical research has also evaluated vitamin C supplements in patients with cancer. High-dose oral vitamin C, 10 grams daily, in patients with advanced cancer does not seem to improve survival or decrease disease progression (4842,4843,106617). However, preliminary clinical research suggests high doses of vitamin C, given intravenously, might have a beneficial effect on some outcomes, including survival rate in some patients with cancer (9809,96704,106617). However, there is no benefit to other patients studied in the case reports and this has not been tested in well-designed clinical trials (9809,96704).
Cardiac arrest. It is unclear if intravenous vitamin C is beneficial for patients after cardiac arrest. Details: A small clinical study conducted in Slovenia in adult survivors of out-of-hospital cardiac arrest shows that administering intravenous vitamin C 1.5 grams every 12 hours for 8 consecutive doses, with the first dose administered within 6 hours of resuscitation, in addition to standard care protects against arrhythmias and reduces the length of intensive care unit (ICU) stay when compared with placebo and standard care. However, intravenous vitamin C does not appear to protect against neurological or myocardial injury, reduce the need for mechanical ventilation, reduce the duration of hospital stay, or increase survival when compared with placebo (113667).
Carpal tunnel syndrome. Vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in adults with mild to moderate carpal tunnel syndrome shows that taking a combination product containing vitamins C, E, B1, B2, B6, and B12, alpha-lipoic acid, acetyl-L-carnitine, phosphatidylserine, and turmeric twice daily for 60 days reduces symptom severity and pain but does not improve measures of hand and wrist function when compared with control (111702). The validity of these effects is limited by a lack of blinding. The study may also be inadequately powered to detect a difference between groups. Additionally, it is unclear if the effects are due to vitamin C, other ingredients, or the combination.
Cervical cancer. It is unclear if oral vitamin C helps to prevent cervical cancer. Details: Observational research has found that higher vitamin C intake is associated with a 33% to 42% reduced odds of cervical neoplasm. Increasing vitamin C intake by 50 mg daily is associated with an 8% reduced odds of cervical neoplasm (34609,98771).
Chronic fatigue syndrome (CFS). Although there is interest in using oral vitamin C for CFS, there is insufficient reliable information about the clinical effects of vitamin C for this condition.
Colistin-induced nephrotoxicity. It is unclear if intravenous vitamin C helps to prevent nephrotoxicity from colistin. Details: A small clinical study shows that intravenous administration of vitamin C 2 grams every 12 hours along with colistin for around 9-10 days does not prevent nephrotoxicity when compared with colistin therapy alone (99839). However, this study was limited by a lack of statistical power to detect differences between the study groups.
Contrast induced nephropathy. It is unclear if oral vitamin C helps to prevent contrast-induced nephropathy (CIN). Details: Some clinical research shows that taking vitamin C before and after coronary angiography reduces the risk of developing CIN by 33% to 55% when compared with placebo in patients with renal dysfunction (12234,90421). However, other clinical evidence published since 2012 suggests that vitamin C given orally and/or intravenously before and after angiography does not reduce the risk of CIN compared with control in high-risk patients with chronic renal insufficiency or diabetes (91232,91236,90410,90425). Reasons for the discrepancies are not entirely clear. However, it is possible that the lack of significant benefit from vitamin C in the latter studies results from the fact that incidences of CIN have become less common than in the past due to avoidance of dehydration, use of smaller catheters, and use of contrast agents with reduced nephrotoxicity (90429).
Coronary artery bypass graft (CABG) surgery. It is unclear if intravenous vitamin C helps to improve patient outcomes after CABG surgery. Details: A small clinical study shows that giving vitamin C 5 grams intravenously (IV) before anesthesia induction and 5 grams in the cardioplegia solution used during surgery shortens the length of stay in the intensive care unit (ICU) by about 8 hours (102127). However, some limited research suggests that IV vitamin C does not resolve cardiac surgery complications. A small clinical study in patients with vasoplegia after receiving CABG and other cardiac surgeries shows that receiving IV vitamin C 1.5 grams every 6 hours after being admitted to the ICU does not improve vasoplegia when compared with control (102981).
Delirium. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Observational research in adults with septic shock has found that receiving intravenous thiamine 400 mg daily with vitamin C 6 grams daily, both in divided doses, is not associated with reduced delirium when compared with control (103001).
Dental plaque. It is unclear if vitamin C in a chewing gum helps to reduce dental plaque formation. Details: A small clinical study in patients with calculus shows that chewing 10 pieces of gum, each containing 60 mg of vitamin C, daily for 3 months reduces the formation of dental calculus, visible plaque, and the number of bleeding sites when compared not chewing gum (83303). The validity of this finding is limited by a lack of placebo group.
Depression. It is unclear if oral vitamin C is beneficial for the treatment or prevention of depression. Details: A small clinical study in children and adolescents shows that taking vitamin C 500 mg orally twice daily in combination with fluoxetine 10-20 mg daily for 6 months reduces most symptoms of major depressive disorder when compared with taking fluoxetine alone (90404). However, a small clinical study in adults shows that taking vitamin C up to 1000 mg daily for 2 months does not improve the response rate or decrease symptoms of depression in adults also taking citalopram when compared with citalopram alone (96708). Reasons for these conflicting results may relate to the age of the patients, study duration, or differences in antidepressant medication being taken. One clinical guideline also provisionally recommends against the use of oral vitamin C to treat patients with depression based on low-quality evidence (110318). Some research has also evaluated vitamin C intake for the prevention of depression. A secondary analysis of pre- and peri-menopausal adults enrolled in the Study of Women's Health Across the Nation (SWAN) program suggests that vitamin C intake is inversely associated with depressive symptoms. This association persisted regardless of age, race, physical activity, body mass index, antidepressant use or menopausal status (108083). The validity of these findings is limited due to the secondary nature of this study; additionally, follow-up time is unclear.
Diabetes. It is unclear if oral vitamin C prevents diabetes. Some low-quality research suggests that vitamin C might improve glycemic control in patients with diabetes. Details: Population research has not found a link between dietary vitamin C and the risk of developing type 2 diabetes (14004). However, low certainty clinical research has found some benefit of taking vitamin C supplements for glycemic control. Two meta-analyses of several small, heterogeneous clinical studies in patients with type 2 diabetes show that taking vitamin C 200-3000 mg daily for 2-48 weeks reduces fasting blood glucose by approximately 11 mg/dL (112478) and glycated hemoglobin (HbA1c) by an average of 0.5% when compared with placebo, standard treatment, or no treatment (105461,112478). Subgroup analyses suggest that durations of supplementation longer than 12 weeks show greater glycemic benefit, and although one meta-analysis suggests there is no dose-response relationship (105461), another meta-analysis suggests that doses of vitamin C 1000 mg and higher are most beneficial for improving glycemic indices (112478). Some research has evaluated the effects of vitamin C supplementation on the lipid profile in patients with diabetes, with mixed findings. One meta-analysis of 17 small clinical studies shows that taking vitamin C 200-3000 mg daily for 2 to 48 weeks improves levels of triglycerides and total cholesterol, but not low-density lipoprotein (LDL) or high-density lipoprotein (HDL) cholesterol. Subgroup analysis suggests that study durations of at least 12 weeks show greater benefit (106621). However, two other meta-analyses in patients with diabetes, one of 16 small heterogenous clinical studies and one of 11 small clinical studies, show no clinically important improvement in lipid levels after vitamin C supplementation (105461,105464).
Dry mouth. Oral vitamin C has only been evaluated in combination with vitamin E; its effect when used alone is unclear. Details: A small clinical trial in patients receiving radiotherapy for head and neck cancer shows that taking vitamin E 100 IU and vitamin C 500 mg twice daily for an average of 3 months improves dry mouth when compared to baseline (99080). The validity of these results is limited by the lack of comparison with a control group.
Endometrial cancer. Increased dietary vitamin C has been linked to reduced risk of endometrial cancer. Details: Population research has found that intake of vitamin C from dietary sources is associated with a slightly decreased risk of endometrial cancer when compared with control. However, this benefit is not observed when results from a prospective cohort study are assessed (34578).
Endometriosis. Oral vitamin C has only been evaluated in combination with vitamin E; its effect when used alone is unclear. Details: A small clinical study in patients with endometriosis and pelvic pain shows that taking vitamin C 1000 mg and vitamin E 800 IU daily for 8 weeks improves dysmenorrhea, dyspareunia, and chronic pelvic pain scores when compared with placebo. Vitamin C and vitamin E supplementation also reduces some biochemical markers of oxidative stress when compared with placebo (106622).
Endoscopy-associated adverse effects. It is unclear if a topical vitamin C spray reduces mucosal irritation in patients undergoing Lugol chromoendoscopy. Details: A small clinical trial in patients receiving a Lugol chromoendoscopy shows that spraying a vitamin C 2% solution after the application of the Lugol iodine 2% solution reduces the severity of mucosal irritation, heartburn, and pain when compared with using a normal saline spray after the Lugol iodine 2% solution (104030).
Esophageal cancer. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Population research has found that higher dietary intake of vitamin C is associated with reduced odds of esophageal adenocarcinoma. A 50 gram increase in dietary vitamin C intake is associated with a 13% reduced odds of esophageal cancer (34551,98770). However, a meta-analysis of clinical research shows that taking a vitamin C supplement in combination with beta-carotene and vitamin E does not reduce the risk of esophageal cancer (34581).
Exercise-induced asthma. Small clinical studies suggest that oral vitamin C may modestly improve symptoms in patients with exercise-induced asthma. Details: A meta-analysis of the available clinical research shows that vitamin C supplementation might reduce exercise-induced breathlessness when compared with placebo or control. However, the available research is of poor quality, and no clear conclusions can be drawn regarding its benefits for exercise-induced asthma (90409).
Exercise-induced muscle damage. It is unclear if oral vitamin C is beneficial in exercise-induced muscle damage. Details: A small clinical study in healthy females shows that taking vitamin C 1000 mg before moderate intensity cycling does not prevent muscle damage when compared with placebo (99837). Another small clinical study in endurance-trained runners shows that taking vitamin C 1000 mg and vitamin E (as alpha-tocopherol) 235 mg 2 hours prior to an exercise protocol does not reduce delayed onset muscle soreness or improve other markers of exercise-induced muscle damage when compared with placebo (109961).
Gallbladder disease. It is unclear if oral vitamin C reduces the risk of gallbladder disease. Details: Cross-sectional epidemiological evidence has found that vitamin C supplementation and increased vitamin C serum levels are associated with a decreased risk of developing gallbladder disease in females, but not males (5877).
Gastric cancer. It is unclear if dietary or supplemental vitamin C reduces the risk of gastric cancer. Details: Most population research has not found an association between DIETARY intake of vitamin C and gastric cancer risk (9194,10822,10819,90083). Also, clinical research shows that taking vitamin C supplements in combination with other antioxidants does not reduce the risk of gastric cancer or precancerous gastric lesions (14447,34581,90085). However, some research suggests that it might be associated with a reduced risk for specific forms of gastric cancer (9838,90083). One clinical study shows that taking vitamin C orally 500 mg daily for 6 months after eradication of Helicobacter pylori infection decreases the incidence of precancerous changes in stomach tissue when compared with no treatment (10359). Also, other clinical research shows that taking vitamin C orally 1 gram daily helps promote the regression of precancerous gastric lesions in people at high risk for gastric cancer (2579). In 2009, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that vitamin C supplements may reduce the risk of gastric cancer. However, the FDA has concluded that it is highly uncertain that vitamin C supplements actually reduce the risk of gastric cancer (102332).
Gastritis. There is limited evidence on the oral use of vitamin C in omeprazole-induced corpus gastritis. Details: A small clinical study shows that taking vitamin C orally 1200 mg daily along with omeprazole decreases corpus gastritis associated with omeprazole therapy in patients with H. pylori infection (10360).
Gout. It is unclear if oral vitamin C helps to prevent or manage gout. Details: Population research in men has found that taking vitamin C 500-1500 mg daily from the diet and/or supplements is associated with up to a 34% reduced risk of gout when compared with less than 250 mg daily (16755). Also, men who ingest over 500 mg of vitamin C daily from the diet and supplements have serum uric acid levels that are slightly lower than men who consume less than 90 mg daily (16820). However, taking supplemental vitamin C 500 mg daily for 8 weeks does not seem to lower serum uric acid levels in patients who already have gout (90423).
Hearing loss. There is limited evidence on the intravenous use of vitamin C in idiopathic sudden sensorineural hearing loss. It is unclear if dietary vitamin C intake can affect the risk of hearing loss. Details: A small clinical study in patients with idiopathic sudden sensorineural hearing loss shows that receiving intravenous high-dose vitamin C 200 mg/kg daily in combination with steroid therapy for 10 days, followed by oral vitamin C 2000 mg daily for 30 days, increases recovery rate two-fold and modestly improves hearing threshold levels when compared with receiving steroid therapy only (90417). In addition, population research in females has found that high dietary intake of vitamin C is associated with a 22% increased risk of developing self-reported hearing loss over a 22-year period when compared with low intake (109807).
Heart transplant complications. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that a combination of vitamin C 500 mg and vitamin E 400 IU, taken twice daily for 1 year starting within the first 2 years after cardiac transplant, reduced the progression of vasculopathy as measured by intravascular ultrasonography (IVUS) when compared with placebo. This suggests that the combination may help slow the progression of CAV (82826).
Hepatitis C. It is unclear if oral vitamin C is beneficial in patients with hepatitis C. Details: A small clinical study in patients with confirmed hepatitis C shows that taking vitamin C 1000 mg daily with conventional therapy (sofosbuvir plus daclatasvir) for 4 weeks improves serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and albumin when compared with conventional therapy alone (109463).
HIV/AIDS. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small, low-quality study in men with HIV shows that taking vitamin C 250 mg daily in combination with vitamin A, beta-carotene, vitamin E, selenium, and coenzyme Q10 does not improve viral load, although it seems to improve markers of oxidative stress when compared to baseline. However, a 1000 mg dose of vitamin C, as well as higher doses of the other antioxidants, do not seem to provide any additional effect (9830).
HIV transmission. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in HIV-positive mothers shows that taking vitamin B, vitamin C, and vitamin E daily during pregnancy and while breast-feeding for 20 weeks seems to reduce child mortality and HIV transmission through breast milk when compared with taking vitamin A (9801).
Hyperphosphatemia. Intravenous vitamin C might be beneficial for reducing phosphate levels in patients with end-stage renal disease. Details: A small clinical study in hemodialysis patients with elevated phosphorus levels suggests that administering vitamin C 500 mg intravenously three times weekly for 8 weeks reduces phosphorus levels about seven-fold when compared with placebo (90414).
Idiopathic interstitial pneumonia. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with idiopathic pulmonary fibrosis, a form of idiopathic interstitial pneumonia, shows that taking a combination of vitamin C 250 mg every other day, vitamin D 50,000 IU daily, and vitamin E 200 IU daily for 12 weeks improves some, but not all, measures of lung function and reduces markers of inflammation and oxidative stress when compared to baseline (109464). The validity of these findings is limited by a lack of placebo control group.
Infertility. It is unclear if oral vitamin C is beneficial in anovulatory females. Details: A very small clinical study suggests that taking vitamin C 400-1000 mg daily might improve fertility, resulting in ovulation and pregnancy in some anovulatory females, when compared to baseline (14018). The validity of these findings is limited by the small study size and lack of a comparator group. However, a very large observational study suggests that there is no association between dietary vitamin C intake and in-vitro fertilization (IVF) outcomes including good oocyte quality, embryo transfer success rates, clinical pregnancy rates, and successful term pregnancy rates in subfertile couples who are candidates for IVF (112097).
Male infertility. It is unclear if oral or intravenous vitamin C is beneficial in males with infertility. Details: A meta-analysis of three small, low-quality clinical trials in males with infertility shows that taking vitamin C up to 1000 mg daily for up to 12 weeks can improve sperm count, motility, and vitality, but does not seem to increase semen volume or sperm concentration, when compared with control (109461). It is unclear if vitamin C can increase pregnancy rates, as these studies did not assess this outcome. A retrospective study in males with or without varicocele-related infertility has found that taking a specific combination product containing vitamin C 90 mg, zinc 10 mg, L-carnitine fumarate 1725 mg, acetyl-L-carnitine 500 mg, coenzyme Q10 20 mg, folic acid 0.2 mg, selenium 0.05 mg, and vitamin B12 0.015 mg (Proxeed Plus, Sigma-Tau) orally twice daily for 6 months improves sperm count, sperm concentration, and sperm motility when compared with baseline. Improvement in semen parameters were greatest in subjects with more severe varicoceles. The validity of this study is limited by the lack of a comparator group (111296).
Mastalgia. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in patients with mastalgia shows that taking a combination of vitamin C 100 mg, vitamin B12, and gamma-linolenic acid daily for 12 weeks does not improve the proportion of patients with minimal or no pain when compared with placebo (111059).
Melasma. It is unclear if topical vitamin C is beneficial in patients with melasma. Details: A small clinical study in patients with bilateral symmetrically distributed facial melasma shows that topical application of 0.5 mL of vitamin C (Cosmotech, Alpha Medical Cosmotech) following dermapen microneedling every 2 weeks for 6 weeks is similarly effective to tranexamic acid for improving melasma severity and pigmented, but not vascular, findings on dermoscopic examination (106939).
Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral vitamin C is beneficial in patients with NAFLD. Details: A clinical study in patients with NAFLD shows that taking vitamin C 250 mg, 1000 mg, or 2000 mg daily for 12 weeks improves some biochemical markers of liver health and glucose metabolism when compared with baseline. However, the improvement from baseline was similar between groups (106942).
Nonalcoholic steatohepatitis (NASH). Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research suggests vitamin C in combination with vitamin E might improve hepatic fibrosis in patients with NASH. However, it does not seem to decrease liver inflammation (14005).
Non-Hodgkin lymphoma. It is unclear if oral vitamin C reduces the risk of developing diffuse large B-cell lymphoma. Details: In one population study, higher dietary or supplemental intake of vitamin C was associated with a reduced risk of diffuse large B-cell lymphoma, a type of non-Hodgkin lymphoma, when compared with lower intake in postmenopausal adults (90945).
Oral cancer. It is unclear if oral vitamin C reduces the risk of developing oral cancer. Details: Population research has found that higher dietary intake of vitamin C is associated with a reduced risk of oral cancer (10821). However, clinical research has not shown benefit with oral vitamin C supplements. A small clinical trial in Japanese adults with oral leukoplakia shows that taking vitamin C 500 mg and beta-carotene 10 mg daily for 12 months does not reduce the development of oral cancer over 5 years when compared with vitamin C 50 mg daily (91384).
Oral leukoplakia. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in Japanese adults with oral leukoplakia shows that taking vitamin C 500 mg and beta-carotene 10 mg daily for 12 months does not improve leukoplakia symptoms or reduce the development of oral cancer over 5 years when compared with vitamin C 50 mg daily (91384).
Osteoarthritis. It is unclear if dietary vitamin C reduces the risk of developing osteoarthritis. Details: Observational research has found that increased vitamin C from dietary sources is associated with a reduced risk of cartilage loss and disease progression in people with osteoarthritis (5881).
Osteoporosis. It is unclear if dietary vitamin C improves bone density or reduces fracture risk in patients at risk for osteoporosis. Details: Some cross-sectional observational research in postmenopausal patients without a history of smoking or estrogen use has found that higher serum vitamin C levels are associated with lower bone mineral density (9828). However, other observational research in a larger population of adults at risk for osteoporosis has found that higher dietary vitamin C intake is not associated with fracture risk (104415).
Ovarian cancer. Dietary vitamin C might not affect the risk of ovarian cancer. Details: Epidemiological research has found that dietary vitamin C intake is not linked with ovarian cancer risk (9193,102977).
Pancreatitis. It is unclear if intravenous vitamin C is beneficial in patients with acute pancreatitis. Details: A small meta-analysis of clinical studies in patients with acute pancreatitis shows that intravenous vitamin C does not improve the odds of developing organ failure when compared with placebo or no intervention. Intravenous vitamin C seems to reduce hospital stay, but not in-hospital mortality (106941).
Parkinson disease. Dietary vitamin C might not affect the risk of developing this condition. Details: Observational research has found that moderate or high dietary intake of vitamin C is not associated with a reduced risk of Parkinson disease (83316).
Periodontitis. Oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. It is also unclear if dietary vitamin C reduces the risk of periodontitis. Details: A small clinical study in patients with moderate or advanced periodontitis shows that taking a supplement containing vitamin C 100 mg, alpha-lipoic acid, coenzyme Q10, cranberry extract, grapeseed extract, selenium, vitamin E, and zinc twice daily for 8 weeks in addition to standard nonsurgical therapy does not improve periodontal indices including bleeding on probing, gingival recession, plaque index, or inflammation, among others, when compared with placebo (111708). It is unclear if these effects are due to vitamin C, other ingredients, or the combination. There is also interest in whether dietary vitamin C intake impacts the risk of periodontitis. Observational research in US adults has found that individuals with dietary intake of vitamin C in the third quartile, but not the second or fourth quartiles, have lower odds of periodontitis when compared with vitamin C intake in the lowest quartile. Furthermore, the investigators identified a non-linear relationship between vitamin C intake and periodontitis risk, suggesting that individuals with intakes either much lower or much higher than 158 mg daily are at increased risk of developing periodontitis (109958).
Peripheral arterial disease (PAD). It is unclear if dietary vitamin C helps to reduce the risk of developing PAD. Details: In females, epidemiological evidence has found that dietary intake of vitamin C of 142 mg daily or greater is associated with a 36% reduced risk of PAD when compared with lower intake levels of less than 80 mg daily (10130).
Physical performance. It is unclear if oral vitamin C helps to improve physical performance and muscle strength in older people. Details: Population research has found that higher intake of dietary vitamin C is associated with improved physical performance and muscle strength in elderly people (14006). In contrast, a small clinical study in elderly men undergoing strength training shows that taking vitamin C 1000 mg and vitamin E 258IU daily for 12 weeks does not increase strength, and might even attenuate increases in muscle mass, when compared with strength training alone (96701).
Pneumonia. It is unclear if oral vitamin C helps to prevent pneumonia. Details: A meta-analysis of two small, low-quality clinical studies in children shows that vitamin C does not seem to reduce the occurrence of pneumonia when compared to control (104033).
Postoperative recovery. It is unclear if oral or intravenous vitamin C improves postoperative recovery. Details: Meta-analyses of clinical research show that oral or intravenous vitamin C can shorten the duration of hospitalization after cardiac surgery when compared with control (91233,96703). However, other research shows no decrease in intensive care or hospital stay with vitamin C supplementation (96705). A meta-analysis of 37 clinical trials in adults undergoing low- to high-risk noncardiac surgery (i.e., orthopedic, abdominal, gynecologic, or kidney transplantation), shows that receiving perioperative vitamin C, either orally or intravenously, does not improve duration of hospitalization or overall mortality when compared with control (108087). There's also some limited evidence that vitamin C might reduce postoperative pulmonary complications such as lung infection, pleural effusion, and pneumothorax. A small clinical trial in low-risk cardiac surgery patients shows that receiving intravenous vitamin C 1 gram 10 minutes after anesthesia might slightly reduce the rate of postoperative pulmonary complications when compared with receiving a saline injection (104034).
Postoperative swelling. It is unclear if vitamin C reduces postoperative swelling after dental surgery. Details: A small observational study in adults undergoing surgery for wisdom tooth extraction shows that taking vitamin C 500 mg three times daily for 7 days in addition to standard treatment reduces swelling 7 days after surgery when compared with control. However, vitamin C does not seem to reduce swelling 3 days after surgery when compared with control, suggesting that longer durations are needed for anti-inflammatory effects (113664).
Premature rupture of membranes (PROM). Oral vitamin C seems to reduce the risk of PROM in some patients; however, the addition of oral vitamin E seems to negate any benefit. Details: A meta-analysis of clinical research shows that taking vitamin C alone decreases the risk of both term and preterm PROM by 45% and 34%, respectively, when compared with placebo or control (96707). Also, a more recent clinical study in patients with a history of PROM shows that taking vitamin C 100 mg daily, starting at 14 weeks' gestation, increases the gestational age at recurrent PROM by around 1 week and increases the gestational age at birth by around 1.3 weeks when compared with placebo (109960). Taking vitamin C in combination with vitamin E, however, does not seem to reduce the risk of term or preterm PROM; some research suggests that it might even increase the risk of non-preterm PROM (83472,96707). However, other research shows that taking vitamin C 1000 mg plus vitamin E 400 IU daily, beginning at 24 to 34 weeks gestation and continuing until delivery, may help increase the latency period until delivery by 5 days and increase gestational age at delivery by almost 1 week when compared with placebo in patients with preterm PROM (90078).
Pressure ulcers. It is unclear if oral vitamin C, when used alone or in combination with other ingredients, can improve the healing of pressure ulcers. Details: A small clinical study in institutionalized patients with pressure ulcers shows that taking vitamin C 500 mg twice daily for 12 weeks does not improve wound closure or increase healing rates when compared with vitamin C 10 mg twice daily (83617). Oral vitamin C has also been evaluated in combination with other ingredients for the treatment of grade II-IV pressure ulcers. Two small clinical studies in hospitalized patients with pressure ulcers shows that administering an oral nutritional supplement enriched with vitamin C, L-arginine, and zinc improves ulcer healing when compared with a standard diet (31953,87173). Also, clinical research in patients living in long-term care facilities shows that taking an oral nutritional supplement enriched in protein, vitamin C, L-arginine, and zinc daily for 9 weeks reduces ulcer area and decreases oozing when compared to baseline (32045). The validity of this finding is limited by the lack of a comparator group.
Radiation proctopathy. Oral vitamin C has only been evaluated in combination with vitamin E; its effect when used alone is unclear. Details: A small clinical study in patients with chronic radiation proctitis shows that vitamin C 500 mg plus vitamin E 400 IU three times daily might improve symptoms when compared with baseline (9825). The validity of these findings is limited by the lack of a comparator group.
Renal cell carcinoma. It is unclear if increased dietary intake of vitamin C helps to reduce the risk of renal cell carcinoma. Details: Population research has found that increased dietary intake of vitamin C is associated with a 12% reduced risk of renal cell carcinoma (98779).
Respiratory tract infections. It is unclear if oral vitamin C is beneficial for preventing respiratory tract infections or reducing the duration of these infections. Details: A meta-analysis of clinical research in children and adults shows that, when compared with placebo, oral vitamin C supplementation reduces the average number of symptomatic days per individual, but does not reduce the average symptom days per respiratory episode. Also, vitamin C intake does not reduce the incidence or severity of respiratory disease or improve recovery in hospitalized patients with respiratory tract infections (108077). The validity of this trial is limited by the high heterogeneity of included studies, which evaluated various vitamin C regimens, ranging from 100 mg to 8 grams daily, as preventive therapy or as an adjuvant to active treatment. A clinical study in children aged 3-10 years shows that taking vitamin C 50 mg in combination with a specific product (Lab4) containing Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium animalis subsp. lactis daily for 6 months reduces the incidence of cough and sore throat by 16% and 20%, respectively, when compared with placebo. However, it did not improve total symptoms, nasal congestion, nasal discharge, or sneezing. Also, aside from a 33% reduction in the average number of days with a sore throat, daily supplementation does not reduce the duration of individual symptoms or total symptoms (106943). It is unclear if these effects are due to vitamin C, the probiotics, or the combination.
Restless legs syndrome (RLS). It is unclear if oral vitamin C helps to reduce symptoms of stress. Details: A small clinical study in hemodialysis patients with RLS shows that taking vitamin C 200 mg daily, alone or in combination with vitamin E 400 mg, for 8 weeks reduces the severity of RLS when compared with placebo (90093). More research is needed to determine if vitamin C is beneficial in treating RLS that is not associated with hemodialysis.
Smoking cessation. It is unclear whether supplemental vitamin C improves lung function in the offspring of pregnant adults with tobacco use disorder. Details: A meta-analysis of large clinical studies in pregnant adults who smoke at least one cigarette daily shows that taking supplemental vitamin C 500 mg daily during pregnancy reduces lower airway resistance and improves lung capacity of the offspring but does not improve airway obstruction when compared with control (113670).
Sunburn. Topical and oral vitamin C has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking vitamin C orally in combination with vitamin E seems to prevent ultraviolet (UV) radiation-induced erythema (sunburn) (4715,4716). Vitamin C in combination with high dose oral RRR-alpha-tocopherol (natural vitamin E) seems to protect against skin inflammation after exposure to UV radiation (4715). Also, applying topical vitamin C in combination with topical vitamin E and melatonin seems to provide modest photoprotective effects when used prior to UV exposure. However, it has no effect when used during or after UV exposure (4713,4714).
Stress. It is unclear if oral vitamin C helps to reduce symptoms of stress. Details: A small clinical study in healthy adults shows that taking vitamin C 3000 mg daily for 14 days modestly reduces blood pressure and subjective stress response to psychological stress when compared with placebo (10353).
Stroke. Observational research has found that although taking vitamin C supplements does not seem to be beneficial, eating more vitamin C-rich food is linked with reduced risk of stroke. Details: Lower plasma levels of vitamin C have been associated with increased stroke risk (90408). Additionally, population research has found that higher dietary intake of vitamin C is associated with a 8% to 19% reduction in stroke risk when compared to lower intake (90408,109779). This reduction appears to be dose-dependent, with each 100 mg/day increase in dietary vitamin C intake associated with about a 17% reduction (90408). However, taking vitamin C supplements has not been found to be associated with reduced stroke risk (1449,90408).
Tetanus. It is unclear if intravenous vitamin C helps to reduce symptoms of tetanus. Details: A low quality clinical trial in children and young adults with tetanus shows that intravenous vitamin C 1 gram daily along with conventional treatment reduces fatality when compared to control (21539).
Tooth extraction. It is unclear if oral vitamin C is beneficial for reducing pain or improving healing after tooth extraction. Details: A small clinical study in healthy patients aged 14-41 years who are undergoing bilateral premolar extraction shows that taking vitamin C 200 mg three times daily, beginning immediately after extraction and continued for 10 days, improves pain on days 1-3, and may reduce mesio-distal wound size between days 1 and 7, when compared with placebo, but not when compared with vitamin C 500 mg three times daily. A dose of 500 mg three times daily did not improve pain scores or extraction wound healing when compared with placebo (108084). The validity of this trial is limited by the short duration of treatment; additionally, this study did not report baseline vitamin C levels.
Urinary tract infections (UTIs). Although there is interest in using oral vitamin C for UTIs, there is insufficient reliable information about the clinical effects of vitamin C for this condition.
Vascular dementia. It is unclear if oral vitamin C reduces the risk of vascular dementia. Details: Population research has found that supplemental intake of vitamin C and vitamin E is associated with a reduced risk of vascular dementia in Japanese-American men (4636). However, when cases in which dementia was diagnosed prior to the study are excluded from data analysis, intake of vitamin C and vitamin E is not associated with a reduced risk of vascular dementia in these patients (9824).
Wound healing. It is unclear if oral vitamin C improves the healing of chronic foot ulcers. It is also unclear if intravenous vitamin C improves healing of surgical wounds after total abdominal hysterectomy. Details: A very small clinical study in adults with chronic foot ulcers shows that taking slow-release vitamin C 500 mg daily for 8 weeks seems to result in a median of 100% ulcer healing, compared with a median of 14% ulcer healing in patients taking glucosamine 1000 mg daily (105456). This finding is limited due to the small and heterogeneous patient population, which included patients with diabetes, vascular disease, and/or vitamin C deficiency. Another small clinical study in patients undergoing total abdominal hysterectomy shows that administration of intravenous vitamin C 1 gram the night before surgery and 1 gram during surgery does not reduce the rate of surgical site infection or wound dehiscence when compared with placebo (109465). However, this study may not have been adequately powered to detect differences between groups. More evidence is needed to rate vitamin C for these uses.

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Safety view details

Below is general information about the safety of the known ingredients contained in the product Aloe Vera & Glucosamine Joint Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe Vera)

LIKELY SAFE ...when aloe gel is used topically and appropriately. Aloe gel-containing formulations have been safely applied in clinical trials (101,11982,12096,12098,12159,12160,12163,12164,17418)(90123,90124,90127,90128,90129,90131,97320,98816,103305). When included in topical cosmetics, the Cosmetic Ingredient Review Expert Panel concluded that aloe-derived anthraquinone levels should not exceed 50 ppm (90122).

POSSIBLY SAFE ...when aloe gel is used orally and appropriately, short-term. Aloe gel has been safely used in a dose of 15 mL daily for up to 42 days or 100 mL of a 50% solution twice daily for up to 4 weeks (11984,12164). Also, a specific aloe gel complex (Aloe QDM complex, Univera Inc.) has been safely used at a dose of approximately 600 mg daily for up to 8 weeks (90121). ...when aloe extract is used orally and appropriately, short-term. Aloe extract has been used with apparent safety in a dose of 500 mg daily for one month (101579). Also, an aloe extract enriched in aloe sterols has been used with apparent safety in a dose of 500 mg daily for 12 weeks (101577).

POSSIBLY UNSAFE ...when aloe latex is used orally. There is some evidence that anthraquinones in aloe latex are carcinogenic or promote tumor growth, although data are conflicting (6138,16387,16388,91596,91597). In 2002, the US FDA banned the use of aloe latex in laxative products due to the lack of safety data (8229). ...when aloe whole-leaf extract is used orally. Aloe whole-leaf extract that has not been filtered over charcoal still contains anthraquinones. This type of aloe whole-leaf extract is referred to as being "nondecolorized". The International Agency for Research on Cancer has classified this type of aloe whole-leaf extract as a possible human carcinogen (91598,91908). Although filtering aloe whole-leaf extract over charcoal removes the anthraquinones, some animal research suggests that this filtered extract, which is referred to as being "decolorized", may still cause gene mutations (91598). This suggests that constituents besides anthraquinones may be responsible for the carcinogenicity of aloe whole-leaf extract. It should be noted that commercial products that contain aloe whole-leaf extract may be labeled as containing "whole leaf Aloe vera juice" or "aloe juice" (91908).

LIKELY UNSAFE ...when aloe latex is used orally in high doses. Ingesting aloe latex 1 gram daily for several days can cause nephritis, acute kidney failure, and death (8,8961).

CHILDREN: POSSIBLY SAFE
when aloe gel is used topically and appropriately. Aloe gel-containing formulations have been safely applied in clinical trials (90124,90131).

CHILDREN: POSSIBLY UNSAFE
when aloe latex and aloe whole leaf extracts are used orally in children. Children younger than 12 years may experience abdominal pain, cramps, and diarrhea (4).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Anthraquinones present in aloe latex and aloe whole leaf extracts have irritant, cathartic, and possible mutagenic effects (4,16387,16388,90122). There are also anecdotal reports and evidence from animal research that anthraquinones or aloe whole leaf extracts might induce abortion and stimulate menstruation; avoid using (4,8,19,90122).

LACTATION: POSSIBLY UNSAFE
when aloe preparations are used orally. Cathartic and mutagenic anthraquinones present in aloe latex and aloe whole leaf extracts might pass into milk; avoid using (4,19).

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CALCIUM

LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

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CHONDROITIN SULFATE (Chondroitin Sulphate)

LIKELY SAFE ...when used orally and appropriately. Chondroitin sulfate has been used safely in doses of up to 2000 mg daily for up to 6 years (1955,2533,13579,17732,22212,42339,42343,42348,42389,42396)(42398,42463,42477,42513,42520,42536,42541,89516,89558,89592)(89596,94360,94381,95788,95792). However, since chondroitin is often derived from bovine cartilage, historically, there was concern about contamination with diseased animal parts (1825). So far, there are no reports of disease transmission to humans due to use of contaminated chondroitin preparations. ...when used topically and appropriately as an ophthalmic viscosurgical device (OVD). Various products containing chondroitin sulfate and sodium hyaluronate have been granted approval by the US Food and Drug Administration (FDA) for use as an adjunct to cataract surgery (89436,89437).

POSSIBLY SAFE ...when used intramuscularly (10149,42397). ...when used topically as eye drops, short-term. Eye drops containing chondroitin sulfate with xanthan gum or glucosamine have been used with apparent safety four times daily for up to 3 months (89591,104443). ...when administered intravesically under the supervision of a physician (42338,42371,42373,42385,42387,42473,42511,42517,42519,109649).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

GLUCOSAMINE (Glucosamine Sulphate)

LIKELY SAFE ...when glucosamine sulfate is used orally and appropriately. Glucosamine sulfate has been used safely in multiple clinical trials at a dose of 1000-1500 mg daily for 4 weeks to 3 years (2604,7026,8942,11340,12461)(14305,16717,89558,89567,94380,94382,95785).

POSSIBLY SAFE ...when glucosamine hydrochloride is used orally and appropriately. Glucosamine hydrochloride has been used with apparent safety at a dose of 1400-1600 mg daily for up to 2 years (4237,13579,14809,18344,42477,89516,89519,95784). Glucosamine hydrochloride 2 grams daily has also been used with apparent safety for up to 3 weeks (103281). ...when N-acetyl glucosamine is used orally and appropriately. N-acetyl glucosamine 100 mg daily has been used with apparent safety for up to 24 weeks (95795). ...when N-acetyl glucosamine is applied topically and appropriately. A 2% N-acetyl glucosamine cream has been safely used for up to 10 weeks (92721). ...when N-acetyl glucosamine is used rectally and appropriately. N-acetyl glucosamine 3-4 grams daily in 2 divided doses has been safely used (10234). ...when glucosamine sulfate is used intramuscularly and appropriately, short-term. Intramuscular glucosamine sulfate seems to be well tolerated when given twice weekly for up to 6 weeks (2605).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

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SELENIUM

LIKELY SAFE ...when used orally and appropriately. Selenium appears to be safe when taken short-term in amounts below the tolerable upper intake level (UL) of 400 mcg daily (4844,7830,7831,7836,7841,9724,9797,14447,17510,17511)(17512,17513,17515,17516,97087,97943,109085); however, there is concern that taking selenium long-term might not be safe. Some evidence shows that consuming a diet containing more than the recommended dietary allowance (RDA) of selenium, which is 55 mcg daily for most adults, is associated with an increased risk for developing type 2 diabetes (99661). Some evidence also shows that taking a selenium supplement 200 mcg daily for an average of 3-8 years increases the risk of developing type 2 diabetes (97091,99661). Higher serum levels of selenium are also associated with an increased risk of developing diabetes and increased mortality (16710,99661). ...when used intravenously. Selenium, as selenious acid, is an FDA-approved drug. Sodium selenite intravenous infusions up to 1000 mcg daily have been safely used for up to 28 days (90347,92910).

POSSIBLY UNSAFE ...when used orally in high doses or long-term. Doses above 400 mcg daily can increase the risk of developing selenium toxicity (4844,7825). Additionally, some evidence shows that consuming a diet containing more than the recommended dietary allowance (RDA) of selenium, which is 55 mcg daily for most adults, is associated with an increased risk for developing type 2 diabetes (99661). There is also concern that taking a selenium supplement 200 mcg daily long-term, for an average of 3-8 years, increases the risk of developing type 2 diabetes (99661). Higher serum levels of selenium are also associated with an increased risk of developing diabetes and increased mortality (16710,99661).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately. Selenium seems to be safe when used short-term in doses below the tolerable upper intake level (UL) of 45 mcg daily for infants up to age 6 months, 60 mcg daily for infants 7 to 12 months, 40-90 mcg daily for children 1 to 3 years, 100-150 mcg daily for children 4 to 8 years, 200-280 mcg daily for children 9 to 13 years, and 400 mcg daily for children age 14 years and older (4844,86095); however, there is some concern that long-term use might not be safe. ...when used via a nasogastric tube in premature infants (7835,9764).

PREGNANCY: POSSIBLY SAFE
when used orally and appropriately. Selenium appears to be safe when used short-term in amounts that do not exceed the tolerable upper intake level (UL) of 400 mcg daily (4844,17507,74419,74481,74391); however, there is concern that long-term use might not be safe.

PREGNANCY: POSSIBLY UNSAFE
when used orally in excessive doses. Doses above 400 mcg daily may cause significant toxicity (4844).

LACTATION: POSSIBLY SAFE
when used orally and appropriately. Selenium appears to be safe when used short-term in amounts that do not exceed the tolerable upper intake level (UL) of 400 mcg daily when taken short-term (4844,74467); however, there is concern that long-term use might not be safe.

LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. Doses above 400 mcg daily may cause significant toxicity (4844,7838). ...when used orally in HIV-positive women. Selenium supplementation in HIV-positive women not taking highly active antiretroviral therapy may increase HIV-1 levels in breast milk (90358).

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VITAMIN C

LIKELY SAFE ...when used orally, topically, intramuscularly, or intravenously and appropriately. Vitamin C is safe when taken orally in doses below the tolerable upper intake level (UL). Tell patients not to exceed the UL of 2000 mg daily (1959,4713,4714,4844). ...when used intravenously or intramuscularly and appropriately. Injectable vitamin C is an FDA-approved prescription product (15).

POSSIBLY UNSAFE ...when used orally in excessive doses. Doses greater than the tolerable upper intake level (UL) of 2000 mg daily can significantly increase the risk of adverse effects such as osmotic diarrhea and gastrointestinal upset (4844).

CHILDREN: LIKELY SAFE
when used orally and appropriately (4844,10352,14443).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive amounts. Tell patients not to use doses above the tolerable upper intake level (UL) of 400 mg daily for children ages 1 to 3 years, 650 mg daily for children 4 to 8 years, 1200 mg daily for children 9 to 13 years, and 1800 mg daily for adolescents 14 to 18 years. Higher doses can cause osmotic diarrhea and gastrointestinal upset (4844).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (4844).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. Tell patients over age 19 not to use doses exceeding the UL of 2000 mg daily when pregnant or breast-feeding and for those 14-18 years of age not to use doses exceeding 1800 mg daily when pregnant or breast-feeding. Higher doses can cause osmotic diarrhea and gastrointestinal upset. Large doses of vitamin C during pregnancy can also cause newborn scurvy (4844); avoid using.

(Read more about VITAMIN C)

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Interactions with Drugs view details

Below is general information about the interactions of the known ingredients contained in the product Aloe Vera & Glucosamine Joint Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe Vera)

ANTICOAGULANT/ANTIPLATELET DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe gel might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.

Details

In vitro research shows that aloe gel can inhibit platelet aggregation. This inhibition was greater than that seen with celecoxib, but less than that seen with aspirin (105501).

ANTIDIABETES DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Aloe might increase the risk of hypoglycemia when taken with antidiabetes drugs.

Details

Preliminary clinical research suggests aloe gel might lower blood glucose levels (11983,12164,19756) and have additive effects when used with antidiabetes drugs. Monitor blood glucose levels closely.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe might decrease the levels and clinical effects of CYP1A2 substrates.

Details

In vitro research shows that aloe extract induces CYP1A2 enzymes (111404).

DIGOXIN (Lanoxin)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = D

Theoretically, aloe latex might increase the risk of adverse effects when taken with cardiac glycosides.

Details

Overuse of aloe latex can increase the risk of adverse effects from cardiac glycoside drugs, such as digoxin, due to potassium depletion. Overuse of aloe, along with cardiac glycoside drugs, can increase the risk of toxicity (19).

DIURETIC DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe latex might increase the risk of hypokalemia when taken with diuretic drugs.

Details

Overuse of aloe latex might compound diuretic-induced potassium loss, increasing the risk of hypokalemia (19).

STIMULANT LAXATIVES

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe latex might increase the risk for fluid and electrolyte loss when taken with stimulant laxatives.

Details

Due to cathartic laxative effects of aloe latex, concomitant use with other stimulant laxatives might compound fluid and electrolyte loss (19,19742,19743,19744).

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, aloe latex might increase the risk of bleeding when taken with warfarin.

Details

Aloe latex has stimulant laxative effects. In some people aloe latex can cause diarrhea. Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding. Advise patients who take warfarin not to take excessive amounts of aloe vera.

(Read more about ALOE)

CALCIUM

ALUMINUM

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.

Details

Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = C

Calcium reduces the absorption of bisphosphonates.

Details

Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Taking calcipotriene with calcium might increase the risk for hypercalcemia.

Details

Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS

Interaction Rating = Minor Be watchful with this combination.

Severity = Moderate • Occurrence = Unlikely • Level of Evidence = D

Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.

Details

Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = D

Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.

Details

Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = B

Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.

Details

Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Theoretically, calcium may reduce the therapeutic effects of diltiazem.

Details

Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce levels of dolutegravir.

Details

Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce levels of elvitegravir.

Details

Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce the absorption and effectiveness of levothyroxine.

Details

Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.

Details

Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce the absorption of quinolone antibiotics.

Details

Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = B

Calcium may reduce levels of raltegravir.

Details

Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Calcium seems to reduce the absorption of sotalol.

Details

Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = C

Calcium seems to reduce the absorption of tetracycline antibiotics.

Details

Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = C

Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.

Details

Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Theoretically, calcium may reduce the therapeutic effects of verapamil.

Details

Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

(Read more about CALCIUM)

CHONDROITIN SULFATE (Chondroitin Sulphate)

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Unlikely • Level of Evidence = D

Taking chondroitin in combination with glucosamine might increase the anticoagulant effects of warfarin. However, the effect of chondroitin alone is unclear.

Details

There have been multiple reports of increased international normalized ratio (INR) in patients taking warfarin with glucosamine, with or without chondroitin. The lack of reports with chondroitin alone seem to suggest that the interactions occurring in these reports may have been due to glucosamine. In two individual case reports, glucosamine/chondroitin combinations were associated with a significant increase in INR in patients previously stabilized on warfarin (11389,16130). Additionally, 20 voluntary case reports to the US Food & Drug Administration (FDA) have linked glucosamine plus chondroitin with increased INR, bruising, and bleeding in patients who were also taking warfarin (16130). There have also been 20 additional case reports to the World Health Organization (WHO) that link glucosamine alone, without chondroitin, to increased INR in patients taking warfarin (16131).

GLUCOSAMINE (Glucosamine Sulphate)

ACETAMINOPHEN (Tylenol, others)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = B

Acetaminophen might interfere with the activity of glucosamine sulfate by interacting with the sulfate portion.

Details

Anecdotal reports suggest that adding glucosamine to an acetaminophen regimen might decrease pain control in patients with osteoarthritis (14806). Some research suggests that the sulfate portion of glucosamine sulfate might contribute to its effect in osteoarthritis. Since acetaminophen metabolism requires sulfur and reduces serum sulfate concentrations, acetaminophen could theoretically interfere with the action of glucosamine sulfate. Conversely, the administration of sulfate could theoretically decrease the effectiveness of acetaminophen in sulfate-deficient people by increasing its clearance (10313).

ANTIDIABETES DRUGS

Interaction Rating = Minor Be watchful with this combination.

Severity = Moderate • Occurrence = Unlikely • Level of Evidence = B

Despite initial concerns, it is unlikely that glucosamine will interfere with the effects of antidiabetes drugs.

Details

In vitro and animal research has suggested that glucosamine might increase insulin resistance or decrease insulin production (371,372,3406,18342,18343). This has raised concerns that taking glucosamine might worsen diabetes and decrease the effectiveness of diabetes drugs. However, clinical research suggests that glucosamine does not have adverse effects on blood glucose or glycated hemoglobin (HbA1C) in healthy, obese, or type 2 diabetes patients (7026,7075,8942,10311,10317,15111).

TOPOISOMERASE II INHIBITORS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically glucosamine may induce resistance to topoisomerase II inhibitors.

Details

In vitro research suggests that glucosamine might induce resistance to etoposide (VP16, VePesid) and doxorubicin (Adriamycin) by reducing inhibition of topoisomerase II, an enzyme required for DNA replication in tumor cells (7639). This effect has not been reported in humans.

WARFARIN (Coumadin)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = D

Glucosamine might increase the anticoagulant effects of warfarin and increase the risk of bruising and bleeding.

Details

In two individual case reports, glucosamine/chondroitin combinations were associated with a significant increase in international normalized ratio (INR) in patients previously stabilized on warfarin (11389,16130). In one case, the increase in INR occurred only after tripling the dose of a glucosamine/chondroitin supplement from 500 mg/400 mg daily to 1500/1200 mg daily (16130). Additionally, 20 voluntary case reports to the U.S. Food & Drug Administration (FDA) have linked glucosamine plus chondroitin with increased INR, bruising, and bleeding in patients who were also taking warfarin (16130). There have also been 20 additional case reports to the World Health Organization (WHO) that link glucosamine alone to increased INR in patients taking warfarin (16131). The mechanism of this interaction is unclear. Glucosamine is a small component of heparin, but is not thought to have anticoagulant activity; however, animal research suggests that it might have antiplatelet activity (16131).

(Read more about GLUCOSAMINE)

SELENIUM

ANTICOAGULANT/ANTIPLATELET DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Details

Clinical research suggests that taking selenium 10 mcg/kg/day can increase bleeding times by increasing prostacyclin production, which inhibits platelet activity (14540). Other clinical research suggests that taking selenium 75 mcg daily, in combination with ascorbic acid 600 mg, alpha-tocopherol 300 mg, and beta-carotene 27 mg, reduces platelet aggregation (74406).

BARBITURATES

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, selenium might prolong the sedating effects of barbiturates.

Details

Laboratory research suggests that selenium can inhibit the hepatic metabolism of barbiturates (14601,14602). Selenium seems to prolong the sedative effect of pentobarbital in animal models (14601).

CONTRACEPTIVE DRUGS

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = B

Contraceptive drugs might increase levels of selenium, although the clinical significance of this effect is unclear.

Details

Some research suggests that oral contraceptives increase serum selenium levels in women taking oral contraceptives; however, other research shows no change in selenium levels (14544,14545,14546,101343). It is suggested that an increase could be due to increased carrier proteins, indicating a redistribution of selenium rather than a change in total body selenium (14545).

GOLD SALTS

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = D

Gold salts might interfere with selenium activity in tissues.

Details

Gold forms complexes with selenium, altering its tissue distribution. Theoretically, this might prevent the normal activity of selenium and produce effects equivalent to deficiency (14547,14548).

IMMUNOSUPPRESSANTS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Details

In vitro research and preliminary clinical evidence suggests that selenium may stimulate the immune system (74483,74445).

NIACIN

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = A

Selenium might reduce the beneficial effects of niacin on high-density lipoprotein (HDL) levels.

Details

A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease (7388,11537). It is not known whether this adverse effect is due to a single antioxidant such as selenium, or to the combination. It also is not known whether it will occur in other patient populations.

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, selenium might interfere with warfarin activity.

Details

Animal research suggests that selenium can increase warfarin activity. Selenium might interact with warfarin by displacing it from albumin binding sites, reducing its metabolism in the liver, or by decreasing production of vitamin K-dependent clotting factors (14541). Selenium can also prolong bleeding times in humans by increasing prostacyclin production, which inhibits platelet activity (14540).

(Read more about SELENIUM)

VITAMIN C

ACETAMINOPHEN (Tylenol, others)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Probable • Level of Evidence = B

High-dose vitamin C might slightly prolong the clearance of acetaminophen.

Details

A small pharmacokinetic study in healthy volunteers shows that taking high-dose vitamin C (3 grams) 1.5 hours after taking acetaminophen 1 gram slightly increases the apparent half-life of acetaminophen from around 2.3 hours to 3.1 hours. Ascorbic acid competitively inhibits sulfate conjugation of acetaminophen. However, to compensate, elimination of acetaminophen glucuronide and unconjugated acetaminophen increases (6451). This effect is not likely to be clinically significant.

ALKYLATING AGENTS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.

Details

The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals, such as cyclophosphamide, chlorambucil, carmustine, busulfan, and thiotepa (391). In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells (14012,14013). More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.

ALUMINUM

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Probable • Level of Evidence = B

Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.

Details

Research in animals and humans shows that vitamin C increases aluminum absorption, theoretically by chelating aluminum and keeping it in solution where it is available for absorption (10549,10550,10551,21556). In people with normal renal function, urinary excretion of aluminum will likely increase, making aluminum retention and toxicity unlikely (10549). Patients with renal failure who take aluminum-containing compounds such as phosphate binders should avoid vitamin C supplements in doses above the recommended dietary allowances.

ANTITUMOR ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, the antioxidant effects of vitamin C might reduce the effectiveness of antitumor antibiotics.

Details

The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs which generate free radicals, such as doxorubicin (391). In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells (14012,14013). More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on chemotherapy.

ASPIRIN

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = B

Acidification of the urine by vitamin C might increase aspirin levels.

Details

It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046). However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction is not clinically significant.

CHOLINE MAGNESIUM TRISALICYLATE (Trilisate)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = B

Acidification of the urine by vitamin C might increase choline magnesium trisalicylate levels.

Details

It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046,4531). However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction probably is not clinically significant.

ESTROGENS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Vitamin C might increase blood levels of estrogens.

Details

Increases in plasma estrogen levels of up to 55% occur under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products (129,130,11161). It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall (129,11161). When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. Increases in plasma estrogen levels may occur when patients who are deficient in vitamin C take supplements (11161). Monitor these patients for estrogen-related side effects.

FLUPHENAZINE (Prolixin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, vitamin C might decrease levels of fluphenazine.

Details

In one patient there was a clinically significant decrease in fluphenazine levels when vitamin C (500 mg twice daily) was started (11017). The mechanism is not known, and there is no further data to confirm this interaction.

INDINAVIR (Crixivan)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Probable • Level of Evidence = B

Vitamin C can modestly reduce indinavir levels.

Details

One pharmacokinetic study shows that taking vitamin C 1 gram orally once daily along with indinavir 800 mg orally three times daily reduces the area under the concentration-time curve of indinavir by 14%. The mechanism of this interaction is unknown, but it is unlikely to be clinically significant in most patients. The effect of higher doses of vitamin C on indinavir levels is unknown (11300,93578).

LEVOTHYROXINE (Synthroid, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Vitamin C can increase levothyroxine absorption.

Details

Two clinical studies in adults with poorly controlled hypothyroidism show that swallowing levothyroxine with a glass of water containing vitamin C 500-1000 mg in solution reduces thyroid stimulating hormone (TSH) levels and increases thyroxine (T4) levels when compared with taking levothyroxine alone. This suggests that vitamin C increases the oral absorption of levothyroxine, possibly due to a reduction in pH (102978).

NIACIN

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = A

Vitamin C might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.

Details

A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease (7388,11537). It is not known whether this adverse effect is due to a single antioxidant such as vitamin C, or to the combination. It also is not known whether it will occur in other patient populations.

SALSALATE (Disalcid)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = B

Acidification of the urine by vitamin C might increase salsalate levels.

Details

It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046). However, short-term use of up to 6 grams/day vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction probably is not clinically significant.

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

High-dose vitamin C might reduce the levels and effectiveness of warfarin.

Details

Vitamin C in high doses may cause diarrhea and possibly reduce warfarin absorption (11566). There are reports of two people who took up to 16 grams daily of vitamin C and had a reduction in prothrombin time (9804,9806). Lower doses of 5-10 grams daily can also reduce warfarin absorption. In many cases, this does not seem to be clinically significant (9805,9806,11566,11567). However, a case of warfarin resistance has been reported for a patient who took vitamin C 500 mg twice daily. Cessation of vitamin C supplementation resulted in a rapid increase in international normalized ratio (INR) (90942). Tell patients taking warfarin to avoid taking vitamin C in excessively high doses (greater than 10 grams daily). Lower doses may be safe, but the anticoagulation activity of warfarin should be monitored. Patients who are stabilized on warfarin while taking vitamin C should avoid adjusting vitamin C dosage to prevent the possibility of warfarin resistance.

(Read more about VITAMIN C)

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Adverse Effects view details

Report an Adverse Reaction to Aloe Vera & Glucosamine Joint Formula

Below is general information about the adverse effects of the known ingredients contained in the product Aloe Vera & Glucosamine Joint Formula. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ALOE (Aloe Vera)

General ...Orally and topically, aloe products are generally well tolerated when used in typical doses. However, oral aloe latex is associated with a greater risk of adverse effects, especially when used in high doses or long-term.
Most Common Adverse Effects:
Orally: Aloe latex may cause abdominal pain, cramps, and diarrhea.
Topically: Burning, erythema, and itching. Contact dermatitis in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Aloe latex is associated with serious adverse effects when taken in high doses or long-term. Cases of acute hepatitis due to a hypersensitivity reaction to aloe leaf extract has been reported.

Dermatologic ...Topically, aloe gel has occasionally been associated with burning (12164,19741,30697,30706), itching (12164,19741,30697), eczema (90122), erythema (19748,30706,90123), contact dermatitis (12163,12164,30695,30736,30737,30738,30740), popular eruption (30732), and urticaria (30712). Also, a case of generalized nummular and popular dermatitis attributed to hypersensitivity has been reported for a 47-year-old male who used aloe leaf gel, both topically and orally, for 4 years (30740).

Endocrine ...A case of severe hypokalemia has been reported for a male breast cancer patient who was undergoing chemotherapy and using aloe vera 1 liter daily orally for 2 weeks. The hypokalemia was attributed to the cathartic effects of aloe and resolved once aloe use was discontinued (30704).

Gastrointestinal ...Orally, aloe latex can cause abdominal pain and cramps. Long-term use or abuse of aloe latex can cause diarrhea, sometimes with hypokalemia, albuminuria, hematuria, muscle weakness, weight loss, arrhythmia, and pseudomelanosis coli (pigment spots in intestinal mucosa). Pseudomelanosis coli is believed to be harmless, and usually reverses with discontinuation of aloe. It is not directly associated with an increased risk of developing colorectal adenoma or carcinoma (6138). Orally, aloe gel may cause nausea, stomach cramps, and other gastrointestinal complaints in some patients (104174,111921,111663).
Topically, applying aloe gel in the mouth may cause nausea within 5 minutes of application in some patients (90124).

Hematologic ...A case of Henoch-Schonlein purpura, characterized by abdominal pain, purpura, and severe arthralgia, has been reported in a 52-year-old male who drank aloe juice prepared from four to five leaflets for 10 days prior to symptom development (91598).

Hepatic ...Cases of acute hepatitis have been reported after ingestion of aloe leaf extracts for between 3 weeks and 5 years. This is thought to be a hypersensitivity reaction (15567,15569,16386,17419,90126,91598). A case of acute hepatitis has also been reported for a 45-year-old female who drank two ounces of Euforia juice (Nuverus International), a product containing green tea, noni, goji, and aloe, daily for one month (90125). However, one small clinical trial in healthy individuals shows that taking aloe gel 2 ounces twice daily for 60 days does not impair liver function (104174).

Renal ...Orally, aloe latex can cause hemorrhagic gastritis, nephritis, and acute kidney failure following prolonged use of high doses (1 gram daily or more) (8961).

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CALCIUM

General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

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CHONDROITIN SULFATE (Chondroitin Sulphate)

General ...Orally and topically, chondroitin sulfate is generally well tolerated. Intramuscular and ophthalmic use also seems to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, bloating, constipation, diarrhea, heartburn, nausea.
Serious Adverse Effects (Rare):
Orally: There have been rare reports of hepatotoxicity.

Cardiovascular ...One case of congestive heart failure and another case of myocardial infarction has been possibly attributed to use of glucosamine hydrochloride and chondroitin sulfate (13579,42477). Also, a case of mesenteric occlusion in one patient was considered possibly related to treatment with chondroitin sulfate and glucosamine (89520).

Dermatologic ...Orally, chondroitin sulfate has been associated with skin symptoms, such as eyelid edema, lower limb edema, alopecia, and skin rash (42513). Combinations of chondroitin sulfate along with glucosamine hydrochloride may also be associated with rash, water retention around eyes and scars, and hives on face, chest, torso, and legs when taken orally (42436,110628). A case of photosensitization that was reproducible with rechallenge has been reported following treatment with oral glucosamine-chondroitin products. However, it is not clear if this effect was due to glucosamine, chondroitin sulfate, or contaminants in the product (10408). A case of rash following treatment with intravesical chondroitin sulfate has been reported to be possibly related to the product (42385).

Gastrointestinal ...Orally, chondroitin might cause nausea, bloating, abdominal pain, diarrhea, constipation, vomiting, dyspepsia, and epigastric burning (42396,42436,42541,89561,110628,111647).

Genitourinary ...Intravesical chondroitin sulfate has been associated with cases of vulvar burning, vaginitis, urinary tract infection (UTI), dysuria, pelvic pain, and other bladder symptoms, such as increased frequency, urgency, or incontinence. However, these effects might be due to catheterization rather than chondroitin sulfate (42385,42387,42473).

Hematologic ...Concern has been expressed about possible anticoagulant activity of oral chondroitin sulfate. However, hematological changes have not occurred in patients taking chondroitin sulfate in clinical trials (760).

Hepatic ...Although relatively uncommon, combinations of glucosamine and chondroitin sulfate have been associated with acute liver injury that mimics autoimmune hepatitis. Two cases of elevated aminotransferase levels have been reported for patients taking glucosamine (form unspecified) and chondroitin sulfate at recommended doses. Aminotransferase levels, which were increased by four- to seven-fold, returned to normal following discontinuation of treatment (89515). Another case of abdominal pain, jaundice, fatigue, and elevated liver enzymes has been reported for a patient who used chondroitin sulfate (Condrosulf) for 2 years followed by a combination of glucosamine sulfate and chondroitin sulfate (Vita Mobility Complex) for 8 weeks. The patient required maintenance treatment with azathioprine to remain in remission (89518). A case of acute cholestatic hepatitis due to Glucosamine Forte, which contains glucosamine hydrochloride, chondroitin sulfate, Devil's claw, and shark cartilage, has been reported (89522). It is unclear whether these adverse events were related to chondroitin sulfate, other ingredients, or the combination.

Musculoskeletal ...Orally, chondroitin has been associated with musculoskeletal and connective-tissue events and disorders (13579,42520,95516).

Neurologic/CNS ...Rare cases of headache have been reported following treatment with products containing a combination of oral chondroitin sulfate and glucosamine hydrochloride or glucosamine sulfate (42436,89561). It is unclear if this effect was due to chondroitin, glucosamine, or the combination.
Patients should adhere to product directions when using chondroitin sulfate products that contain manganese. When taken at doses slightly higher than the recommended dose, these products can sometimes supply greater than the tolerable upper limit (UL) for manganese of 11 mg per day. Ingestion of more than 11 mg per day of manganese might cause significant central nervous system toxicity (7135).

Ocular/Otic ...A case of bilateral pinna chondritis (inflammation of the cartilage of the external ear) has been reported for a patient who received supplements containing glucosamine and chondroitin sulfate (42503).

Pulmonary/Respiratory ...A case of asthma exacerbation has been reported occurred following use of an oral glucosamine and chondroitin sulfate combination product (10002).

GLUCOSAMINE (Glucosamine Sulphate)

General ...Orally, all forms of glucosamine seem to be well tolerated. Topically and rectally, N-acetyl glucosamine also seems to be well tolerated. Intramuscularly, glucosamine sulfate seems to be well tolerated. However, a thorough evaluation of safety outcomes has not been conducted for non-oral routes of administration.
Most Common Adverse Effects:
Orally: Bloating, constipation, cramps, diarrhea, heartburn, nausea.
Serious Adverse Effects (Rare):
Orally: There have been rare reports of severe allergic reactions and hepatotoxicity.

Cardiovascular ...One case of mesenteric occlusion in a clinical trial was considered possibly related to use of oral glucosamine hydrochloride and chondroitin sulfate (89520).
Some observational research has found that glucosamine use in patients with osteoarthritis is associated with a higher risk of cardiovascular disease (CVD) events when compared with non-use (109642). However, glucosamine users tended to be older, have multiple comorbidities, and be on antihyperlipidemic or antiplatelet therapy. Furthermore, other observational research in healthy adults has found that glucosamine use is associated with a reduced risk of fatal and non-fatal CVD events (99682). Higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and CVD risk.

Dermatologic ...Orally, glucosamine might cause skin reactions, including itching, rash, and erythema (2608,20084,89567,110628,113636). Also, fingernail and toenail toughening, with an increased rate of growth, has been reported (89572). Topically, N-acetyl glucosamine 2% with niacinamide 4% cream might cause rare skin reactions (92721). Photosensitization that was reproducible with re-challenge was reported in a case report of an individual using glucosamine (form unknown) and chondroitin (10408).

Endocrine ...Orally, glucosamine does not seem to impact blood glucose. Preliminary research and anecdotal reports have found that various forms of glucosamine might increase insulin resistance or decrease insulin production, increasing fasting plasma glucose levels (22,371,372,1203,3406,5059,7637,14810). This has raised concerns that taking glucosamine sulfate might worsen diabetes and decrease the effectiveness of diabetes drugs. However, clinical research suggests that various forms of glucosamine do not have adverse effects on blood glucose or glycated hemoglobin (HbA1C) in healthy, obese, patients with type 2 diabetes or impaired glucose tolerance (7026,7075,7638,8942,10311,10317,12107,14808,15111,89563).

Gastrointestinal ...Orally, glucosamine has been associated with gastrointestinal problems, including epigastric and abdominal pain, cramps, heartburn, diarrhea, nausea, dyspepsia, vomiting, constipation, and flatulence (1520,2608,16717,20084,20104,20105,89561,89562,89567,89568)(108897,110628,111647,113636). In older persons, use of glucosamine sulfate is associated with oral dryness (89564). In a clinical trial, a case of Helicobacter pylori gastritis was considered probably related to the use of glucosamine hydrochloride (89516).

Hepatic ...Although relatively uncommon, combinations of glucosamine and chondroitin sulfate have been associated with acute liver injury that mimics autoimmune hepatitis. Of 151 patients at an outpatient clinic for liver diseases, 23 acknowledged use of products containing glucosamine (form unspecified) and/or chondroitin. However, only 2 cases had an apparent relationship between transaminase elevation and the use of recommended doses of glucosamine and chondroitin sulfate. Aminotransferase levels, which were increased by four- to seven-fold, returned to normal following discontinuation of treatment (89515). In another case, a 65-year-old male presented to the hospital with signs and symptoms of drug-induced autoimmune hepatitis. The patient had used Condrosulf, containing chondroitin sulfate, for two years, followed by Vita Mobility Complex, containing chondroitin sulfate and glucosamine sulfate, for 8 weeks. The patient required maintenance treatment with azathioprine to remain in remission (89518). A case of acute cholestatic hepatitis due to Glucosamine Forte, which contains glucosamine hydrochloride, chondroitin sulfate, Devil's claw, and shark cartilage, has been reported (89522). It is unclear whether these adverse events were related to glucosamine, other ingredients, or the combination.

Immunologic ...There is some concern that glucosamine products might cause allergic reactions in sensitive individuals. One review of glucosamine-related adverse events in Australia found that 72% of all reports involved hypersensitivity reactions. Of these reactions, 35% were mild, including pruritis, urticaria, and lip edema, 49% were moderate, including dyspnea, and 16% were severe, including gait disturbance, somnolence, and hypotension. Anaphylaxis was reported in 1.5% of cases (102115). Also, in one clinical trial, a single patient developed allergic dermatitis considered to be likely due to glucosamine hydrochloride (89516). Glucosamine is derived from the exoskeletons of shrimp, lobster, and crabs. However, it is unclear if these adverse reactions were due to a shellfish sensitivity or general atopy. Additionally, shellfish allergies are caused by IgE antibodies to antigens in the meat of shellfish, not to antigens in the exoskeleton. Regardless, it is possible that some glucosamine products might be contaminated by this allergen during production (102115).

Neurologic/CNS ...Orally, glucosamine has been reported to cause drowsiness and headache (2608,89561,113636). Glucosamine plus chondroitin combination products that also contain manganese (e.g., CosaminDS) should always be taken according to product directions. When taken at doses slightly higher than the recommended dose, these products can sometimes supply greater than the tolerable upper limit (UL) for manganese which is 11 mg/day. Ingestion of more than 11 mg/day of manganese might cause significant central nervous system toxicity (7135).

Ocular/Otic ...In older persons, use of glucosamine sulfate has been associated with ocular dryness (89564). Increased intraocular pressure has occurred with glucosamine sulfate supplementation (89573,112460). Data from the FDA MedWatch adverse event reporting system shows that 0.21% of subjects taking glucosamine reported glaucoma, which is significantly greater than the 0.08% of subjects who reported glaucoma while using any other drug (112460).

Pulmonary/Respiratory ...Cases of asthma exacerbations associated with the use of glucosamine (form unknown)-chondroitin products have been reported (10002).

Renal ...Anecdotal reports have associated glucosamine with nephrotoxicity signals such as modestly elevated creatine phosphokinase and 1+ to 2+ proteinuria, but changes in kidney function have not been reported in long-term studies (7026,8942,10408,10409). It was also noted that effects may have been due to other concurrent medications or impurities in glucosamine-chondroitin products. Cases of acute interstitial nephritis induced by glucosamine (form unknown) have also been reported (89523).

Other ...There has been concern that glucosamine might increase the risk of metabolic disturbances resulting in increased cholesterol levels and blood pressure. However, glucosamine does not appear to increase the risk of these adverse effects. Taking glucosamine sulfate for up to 3 years does not significantly increase blood glucose or lipid levels, or cause any other disturbances in metabolism (7026,7075,8942,10311,10317).

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SELENIUM

General ...Orally, selenium is generally well-tolerated when used in doses that do not exceed the tolerable upper intake level (UL) of 400 mcg daily. Intravenously, selenium is generally well-tolerated.
Most Common Adverse Effects:
Orally: Gastric discomfort, headache, and rash. Excessive amounts can cause alopecia, dermatitis, fatigue, nail changes, nausea and vomiting, and weight loss.
Serious Adverse Effects (Rare):
Orally: Excessive ingestion has led to cases of multi-organ failure and death.

Dermatologic ...Excess selenium can produce selenosis in humans, affecting liver, skin, nails, and hair (74304,74326,74397,74495,90360) as well as dermatitis (74304). Results from the Nutritional Prevention of Cancer Trial conducted among individuals at high risk of nonmelanoma skin cancer demonstrate that selenium supplementation is ineffective at preventing basal cell carcinoma and that it increases the risk of squamous cell carcinoma and total nonmelanoma skin cancer (10687). Mild skin rash has been reported in patients taking up to 200 mcg of selenium daily for up to 12 months (97943).

Endocrine ...Multiple clinical studies have found an association between increased intake of selenium, either in the diet or as a supplement, and the risk for type 2 diabetes (97091,99661). One meta-analysis shows that a selenium plasma level of 90 mcg/L or 140 mcg/L is associated with a 50% or 260% increased risk for developing type 2 diabetes, respectively, when compared with plasma levels below 90 mcg/L. Additionally, consuming selenium in amounts exceeding the recommended dietary allowance (RDA) is associated with an increased risk of developing diabetes when compared with consuming less than the RDA daily. Also, taking selenium 200 mcg daily as a supplement is associated with an 11% increased risk for diabetes when compared with a placebo supplement (99661).
Hypothyroidism, secondary to iodine deficiency, has been reported as a result of selenium intravenous administration (14563,14565). One large human clinical trial suggested a possible increased risk of type 2 diabetes mellitus in the selenium group (16707).

Gastrointestinal ...In human research, nausea, vomiting, and liver dysfunction has been reported as a result of high selenium exposure (74439,74376). Mild gastric discomfort has been reported in patients taking up to 200 mcg of selenium daily for up to 12 months (97943).

Genitourinary ...The effect of selenium supplementation on semen parameters is unclear. In human research, selenium supplementation may reduce sperm motility (9729); however, follow-up research reported no effect on sperm motility or any other semen quality parameter (74441).

Neurologic/CNS ...Chronic exposure to organic and inorganic selenium may cause neurotoxicity, particularly motor neuron degeneration, leading to an increased risk of amyotrophic lateral sclerosis (ALS) (74304). Mild headache has been reported in patients taking up to 200 mcg of selenium daily for up to 12 months (97943).

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VITAMIN C

General ...Orally, intravenously, and topically, vitamin C is well-tolerated.
Most Common Adverse Effects:
Orally: Abdominal cramps, esophagitis, heartburn, headache, osmotic diarrhea, nausea, vomiting. Kidney stones have been reported in those prone to kidney stones. Adverse effects are more likely to occur at doses above the tolerable upper intake level of 2 grams daily.
Topically: Irritation and tingling.
Serious Adverse Effects (Rare):
Orally: There have been rare case reports of carotid inner wall thickening after large doses of vitamin C.
Intravenously: There have been case reports of hyperoxalosis and oxalate nephropathy following high-dose infusions of vitamin C.

Cardiovascular ...Evidence from population research has found that high doses of supplemental vitamin C might not be safe for some people. In postmenopausal adults with diabetes, supplemental vitamin C intake in doses greater than 300 mg per day is associated with increased risk of cardiovascular mortality. However, dietary intake of vitamin C is not associated with this risk. Also, vitamin C intake is not associated with an increased risk of cardiovascular mortality in patients without diabetes (12498).
Oral supplementation with vitamin C has also been associated with an increased rate of carotid inner wall thickening in men. There is preliminary evidence that supplemental intake of vitamin C 500 mg daily for 18 months can cause a 2.5-fold increased rate of carotid inner wall thickening in non-smoking men and a 5-fold increased rate in men who smoked. The men in this study were 40-60 years old (1355). This effect was not associated with vitamin C from dietary sources (1355).
There is also some concern that vitamin C may increase the risk of hypertension in some patients. A meta-analysis of clinical research suggests that, in pregnant patients at risk of pre-eclampsia, oral intake of vitamin C along with vitamin E increases the risk of gestational hypertension (83450). Other clinical research shows that oral intake of vitamin C along with grape seed polyphenols can increase both systolic and diastolic blood pressure in hypertensive patients (13162).

Dental ...Orally, vitamin C, particularly chewable tablets, has been associated with dental erosion (83484).

Dermatologic ...Topically, vitamin C might cause tingling or irritation at the site of application (6166). A liquid containing vitamin C 20%, red raspberry leaf cell culture extract 0.0005%, and vitamin E 1% (Antioxidant and Collagen Booster Serum, Max Biocare Pty Ltd.) has been reported to cause mild tingling and skin tightness (102355). It is unclear if these effects are due to vitamin C, the other ingredients, or the combination.

Gastrointestinal ...Orally, the adverse effects of vitamin C are dose-related and include nausea, vomiting, esophagitis, heartburn, abdominal cramps, gastrointestinal obstruction, and diarrhea. Doses greater than the tolerable upper intake level (UL) of 2000 mg per day can increase the risk of adverse effects such as osmotic diarrhea and severe gastrointestinal upset (3042,4844,96707,104450). Mineral forms of vitamin C, such as calcium ascorbate (Ester-C), seem to cause fewer gastrointestinal adverse effects than regular vitamin C (83358). In a case report, high dose intravenous vitamin C was associated with increased thirst (96709).

Genitourinary ...Orally, vitamin C may cause precipitation of urate, oxalate, or cysteine stones or drugs in the urinary tract (10356). Hyperoxaluria, hyperuricosuria, hematuria, and crystalluria have occurred in people taking 1 gram or more per day (3042,90943). Supplemental vitamin C over 250 mg daily has been associated with higher risk for kidney stones in males. There was no clear association found in females, but the analysis might not have been adequately powered to evaluate this outcome (104029). In people with a history of oxalate kidney stones, supplemental vitamin C 1 gram per day appears to increase kidney stone risk by 40% (12653). A case of hematuria, high urine oxalate excretion, and the presence of a ureteral stone has been reported for a 9-year-old male who had taken about 3 grams of vitamin C daily since 3 years of age. The condition resolved with cessation of vitamin C intake (90936).

Hematologic ...Prolonged use of large amounts of vitamin C can result in increased metabolism of vitamin C; subsequent reduction in vitamin C intake may precipitate the development of scurvy (15). In one case, a patient with septic shock and a large intraperitoneal hematoma developed moderate hemolysis and increased methemoglobin 12 hours after a high-dose vitamin C infusion. The patient received a blood transfusion and the hemolysis resolved spontaneously over 48 hours (112479).

Neurologic/CNS ...Orally, the adverse effects of vitamin C are dose-related and include fatigue, headache, insomnia, and sleepiness (3042,4844,83475,83476).

Renal ...Hyperoxalosis and oxalate nephropathy have been reported following high-dose infusions of vitamin C. Hyperoxalosis and acute kidney failure contributed to the death of a 76-year-old patient with metastatic adenocarcinoma of the lung who received 10 courses of intravenous infusions containing vitamins, including vitamin C and other supplements over a period of 1 month. Dosages of vitamin C were not specified but were presumed to be high-dose (106618). In another case, a 34-year-old patient with a history of kidney transplant and cerebral palsy was found unresponsive during outpatient treatment for a respiratory tract infection. The patient was intubated for acute hypoxemic respiratory failure, initiated on vasopressors, hydrocortisone, and antibacterial therapy, and received 16 doses of vitamin C 1.5 grams. Serum creatinine level peaked at greater than 3 times baseline and the patient required hemodialysis for oliguria and uncontrolled acidosis. Kidney biopsy revealed oxalate nephropathy with concomitant drug-induced interstitial nephritis (106625). In another case, a 41-year-old patient with a history of kidney transplant presented with fever, nausea, and decreased urine output 4 days after receiving intravenous vitamin C 7 grams for urothelial carcinoma. Serum creatinine levels increased from 1.7 mg/dL to 7.3 mg/dL over those 4 days, and hemodialysis was initiated 3 days after admission due to anuria. Renal biopsy confirmed the diagnosis of acute oxalate nephropathy (109962).

Other ...Intravenously, hypernatremia and falsely elevated ketone levels is reported in a patient with septic shock and chronic kidney disease after a high-dose vitamin C infusion. The hypernatremia resolved over 24 hours after cessation of the infusion (112479).

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