Probiotic Supplement Strawberry [Discontinued] by Bio-Kids Plus

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)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Antibiotic-associated diarrhea. Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking a specific L. casei-containing combination product (Bio-K+ CI1285) may be beneficial for preventing antibiotic-associated diarrhea. This combination product provides L. casei LBC80R, Lactobacillus acidophilus CL1285 and Lacticaseibacillus rhamnosus CLR2 as 100 billion colony-forming units (CFUs) daily (25494,95402,95403) However, taking L. casei might not help with the treatment of antibiotic-associated diarrhea. Clinical research in hospitalized patients with antibiotic-associated diarrhea shows that taking a combination of L. casei 20 million CFUs and Bifidobacterium breve 50 million CFUs 3 times daily does not reduce the average duration of diarrhea, the frequency of healing, or relapse rates, when compared with taking placebo (111006).
• Atopic dermatitis (eczema). Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In children under two years of age with atopic dermatitis who are on a cow's milk protein elimination diet, clinical research shows that taking a specific mixture (Latopic, Biomed S.A.) providing 1 billion colony-forming units (CFUs) of L. casei ôOCK 0919 50%, Lacticaseibacillus rhamnosus ŁOCK 0900 25%, and L. rhamnosus ôOCK 0908 25% for 3 months increases the odds of a 30% or greater improvement in symptom scores by about 2.6-fold when compared with placebo. However, there was no difference in the absolute symptom scores between groups. Beneficial effects of this combination were greater in children confirmed to have allergen sensitization (107510). Other clinical research in children ages 4-17 years shows that taking 1 billion CFUs of a 1:1:1 combination of L. casei CECT 9104, Bifidobacterium lactis CECT 8145, and Bifidobacterium longum CECT 7347 for 12 weeks modestly reduces symptom severity and the need for topical corticosteroids when compared with placebo (107531).
• Cancer. Although there has been interest in using oral Lacticaseibacillus casei for cancer prevention or treatment, there is insufficient reliable information about the clinical effects of L. casei for this condition.
• Clostridioides difficile infection. Some early research suggests that oral Lacticaseibacillus casei may be beneficial for preventing a first C. difficile infection. However, the quality of evidence is generally poor, and taking oral L. casei does not seem to be beneficial for the prevention of C. difficile recurrence. Details: Evidence from clinical and observational research investigating the effect of L. casei on C. difficile occurrence or recurrence is weak. Most studies use this species in combination with one or more additional probiotic species, including a specific product (Bio-K+ Cl1285) providing L. casei LBC80R and Lactobacillus acidophilus CL1285 and a specific product (Bio-K+ 50 Billion; Bio-K Plus International) providing L. casei LBC80R, L. acidophilus CL1285, and Lacticaseibacillus rhamnosus CLR2 as 50 or 100 billion CFUs daily (25494,90231,90934,95369,95403,107529). Observational research has found that providing a specific combination (Bio-K+ 50 Billion; Bio-K Plus International) of L. casei LBC80R, L. rhamnosus CLR2, and L. acidophilus CL1285 as 50-100 billion colony-forming units (CFUs) daily for 5 days to patients who are on antibiotics for at least 2 days reduces the hospital-wide incidence of C. difficile by approximately 40%. The incidence rate was decreased by at least 50% in the highest risk individuals taking this combination (107529). Current guidelines from the Infectious Diseases Society of America (IDSA) state that there is insufficient information to recommend administration of probiotics for the primary prevention of C. difficile-associated diarrhea (107538).
• Constipation. Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Combinations of probiotics containing L. casei appear to increase stool frequency and improve symptoms of functional constipation in adults. These combinations include Hexbio, containing L. casei, Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. lactis, Bifidobacterium bifidum, Bifidobacterium longum, and Bifidobacterium longum subsp. infantis 30 billion CFUs twice daily for 7 days (90266), and ID-HWS1000, containing L. casei IDCC 3451, Lactiplantibacillus plantarum IDCC 3501, Lacticaseibacillus rhamnosus IDCC 3201, Bifidobacterium animalis subsp. lactis IDCC 4301, Bifidobacterium breve IDCC 4401, Lactococcus lactis IDCC 2301, xylooligosaccharide, and dietary fiber as nondigestible maltodextrin, oat fiber, and psyllium husk fiber (107517).
• Depression. Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with major depression shows that taking L. casei, Lactobacillus acidophilus, and Bifidobacterium bifidum daily for 8 weeks reduces symptoms of depression measured on the Beck Depression Inventory (BDI) when compared with placebo (99780). However, the validity of the results from this study is limited by incomplete reporting. For example, patient baseline BDI scores were not reported.
• Diabetes. It is unclear if oral Lacticaseibacillus casei is beneficial for treatment of type 2 or gestational diabetes. Details: In patients with gestational diabetes, clinical research shows that taking a combination of freeze-dried L. casei, Lactobacillus acidophilus, and Bifidobacterium bifidum each as 2 billion colony-forming units (CFUs) per gram daily for 6 weeks improves fasting blood glucose levels and glycemic control when compared with placebo (95416,98430). Furthermore, a sub-analysis of a meta-analysis of clinical research investigating the effects of L. casei as part of multi-ingredient probiotic and prebiotic products shows that taking products containing L. casei modestly reduces fasting insulin levels and improves insulin resistance in this population. There were also modest reductions in triglyceride levels; however, the effects on fasting blood glucose were not significant (111796). It is unclear from these studies if any beneficial effects are related to L. casei, L. acidophilus, Bifidobacterium bifidum, or the combination. Limited evidence from mainly small clinical trials has also assessed the effects of L. casei for type 2 diabetes. In one study, taking L. casei 100 million CFUs daily for 8 weeks reduces fasting blood glucose by about 28 mg/dL when compared with placebo. There was no effect on glycated hemoglobin; however, the duration was inadequate to demonstrate an effect (99786). In another study, taking a specific product (Familact) containing L. casei and six other probiotic strains daily for 6 weeks reduces fasting blood glucose, but does not affect plasma insulin, when compared with placebo (99790).
• Diarrhea. Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in children with dysentery being treated with ceftriaxone shows that taking a specific combination probiotic sachet (Kidilact, Zisttakhmir Company) containing L. casei, Lactobacillus acidophilus, Lacticaseibacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus, Bifidobacterium longum subsp. infantis, Bifidobacterium breve, and Streptococcus thermophilus daily for 5 days modestly reduces the duration of diarrhea, hospitalization, and blood in diarrhea when compared with control (102417). Although The European Society for Pediatric Infectious Diseases recommends probiotics in hospitalized children with diarrhea (98469) and the Infectious Disease Society of America (IDSA) recommends probiotics for the outpatient treatment of acute diarrhea (95388), both guidelines note that most evidence is low quality.
• Helicobacter pylori. It is unclear if oral Lacticaseibacillus casei is beneficial for H. pylori eradication in adults or children. Details: Clinical research in adults shows that taking L. casei along with six other probiotics in conjunction with bismuth quadruple therapy does not seem to improve H. pylori eradication rates when compared with placebo and bismuth quadruple therapy (90291). Also, taking a combination of L. casei and Lactobacillus acidophilus without any standard H. pylori therapies does not improve H. pylori eradication rates (12766). However, a clinical study in children shows that taking a fermented milk product containing L. casei DN-114 001 for 14 days along with triple therapy comprised of omeprazole, amoxicillin, and clarithromycin for 7 days improves the H. pylori eradication rate to approximately 85%, compared with 61% of those given triple therapy alone (107544).
• HIV/AIDS. Although there has been interest in using oral Lacticaseibacillus casei for HIV/AIDS, there is insufficient reliable information about the clinical effects of lactobacillus for this condition.
• Hyperlipidemia. It is unclear if oral Lacticaseibacillus casei is beneficial for hyperlipidemia. Details: In patients with primary hyperlipidemia, clinical research shows that taking L. casei 200 million colony-forming units in combination with red yeast rice twice daily for 8 weeks does not have beneficial effects on low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, or triglyceride levels, when compared with taking red yeast rice alone. Taking L. casei seems to modestly reduce diastolic blood pressure in this population; however, it is unclear if these changes are clinically significant (112517).
• Hypertension. It is unclear if oral Lacticaseibacillus casei is beneficial for lowering blood pressure. Details: A meta-analysis of 18 clinical trials shows that taking various species of lactobacilli as 100 million to 1.5 trillion colony-forming units daily for 3-24 weeks reduces systolic and diastolic blood pressure by 3 mmHg and 1.5 mmHg, respectively, when compared with placebo in various populations. However, sub-group analyses of three clinical trials show that these benefits do not occur in clinical research investigating the effects of L. casei, specifically (105135).
• Irritable bowel syndrome (IBS). Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in patients with diarrhea-predominant IBS shows that taking a specific multi-species probiotic (NordBiotic, MBM Biotix) containing L. casei LC130, Lacticaseibacillus rhamnosus LR110, Lacticaseibacillus paracasei LPC100, Lactobacillus acidophilus LA120, Lactiplantibacillus plantarum LP140, Bifidobacterium breve BB010, Bifidobacterium longum BL020, Bifidobacterium bifidum BF030, Bifidobacterium animalis subsp. lactis BL040, and Streptococcus thermophilus ST250 as 2.5 billion colony-forming units (CFUs) total twice daily for 8 weeks improves overall symptom severity, as well as pain severity, pain frequency, and quality of life, when compared with placebo. Symptom severity was rated as mild by approximately 60% of those taking the probiotic mixture, compared with 30% of those taking placebo (107516). However, clinical research shows that taking another multi-species combination of L. casei LBC80R, L. acidophilus CL1285, and L. rhamnosus CLR2 50 billion CFUs each daily for 3 months does not improve symptoms in patients with IBS when compared with placebo (99789).
• Lyme disease. Although there has been interest in using oral Lacticaseibacillus casei for Lyme disease, there is insufficient reliable information about the clinical effects of lactobacillus for this condition.
• Necrotizing enterocolitis (NEC). It is unclear if oral Lacticaseibacillus casei is beneficial or safe for NEC prevention. Details: Most meta-analyses of clinical research show that giving lactobacilli enterally reduces the risk of NEC and/or severe NEC in preterm, mainly very low birth weight (VLBW), infants. Some meta-analyses support the use of lactobacilli in combination with bifidobacteria, as opposed to lactobacilli alone for reducing the risk of NEC. However, the effects of L. casei specifically are unclear (95344,95351,103437,103445,104157,105162,105164). Also, guidance among regulatory agencies and clinical organizations varies with respect to the use of probiotics in very low birth weight infants under 1000 grams. The US Food and Drug Administration (FDA) warns that preterm infants given probiotics are at risk of serious infections caused by the bacteria or fungi contained in probiotics due to cases reported in this group of infants (111610). Also, The American Academy of Pediatrics does not support the routine administration of probiotics to preterm infants, particularly those with a birth weight below 1000 grams, due to conflicting data on safety and efficacy and potential for harm in this vulnerable population (111608). The Canadian Paediatric Society, the American Gastroenterological Association, and the European Society for Paediatric Gastroenterology, Hepatology and Nutrition state that probiotic combinations may be of benefit in reducing the incidence of NEC in preterm neonates over 1000 grams. However, L. casei is not specifically recommended (103003,111609,111611).
• Nonalcoholic fatty liver disease (NAFLD). Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in adults with NAFLD shows that taking a combination of L. casei BCMC 12,313, Lactobacillus acidophilus BCMC 12,130, Lactobacillus delbrueckii subsp. lactis BCMC 12,451, Bifidobacterium bifidum BCMC 02290, Bifidobacterium longum subsp. infantis BCMC 02129, and Bifidobacterium longum BCMC 02120 as 30 billion colony-forming units twice daily for 6 months has no beneficial effects on hepatic steatosis or fibrosis or on levels of liver enzymes, blood lipids, or fasting blood glucose, when compared with placebo (107523).
• Polycystic ovary syndrome (PCOS). Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In patients with PCOS, clinical research shows that taking a combination of L. casei T2 (IBRC-M10783), Lactobacillus acidophilus T16 (IBRC-M10785), and Bifidobacterium bifidum T1 (IBRC-M10771) as 2 billion colony-forming units (CFUs) each, plus inulin 800 mg, daily for 12 weeks modestly reduces serum insulin and triglyceride levels and improves insulin resistance and insulin sensitivity when compared with placebo. However, it does not alter cholesterol or fasting blood glucose levels (105159). Clinical research also shows that 31.3% of patients with PCOS taking L. casei in combination with other probiotics daily for 6 months had regular menstrual cycles compared with 12.5% of those taking placebo. There were also modest improvements in testosterone levels and waist circumference, but not other hormones, insulin resistance, body weight, or most measures of quality of life. The product provided L. casei UBLC-42 1 billion CFUs, along with Lactiplantibacillus plantarum UBLP-40, Lactobacillus acidophilus UBLA-34, Lacticaseibacillus casei UBLC-42, Limosilactobacillus fermentum UBLF-31, Lacticaseibacillus rhamnosus UBLR-58, Limosilactobacillus reuteri UBLRu-87, Bifidobacterium bifidum UBBB-55, and fructo-oligosaccharides (FOS) daily for 2 months and then twice daily for 4 months. All patients also underwent dietary and lifestyle changes (110974).
• Pregnancy-induced nausea and vomiting. Oral Lacticaseibacillus casei has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small preliminary clinical trial shows that taking probiotics during pregnancy reduces the severity and duration of nausea and vomiting by 16% to 54%. There was also a small benefit on stool hardness. A specific probiotic (Probiotics 10, Nature's Bounty) was taken as 2 capsules daily for two back-to-back cycles comprised of six days with probiotics and two days without. Each capsule contained a total of 10 billion colony-forming units (CFUs) of L. casei Lc-11, Lactiplantibacillus plantarum 299v and DSM 15312, Lactobacillus delbrueckii subsp. bulgaricus Lb-87, Lacticaseibacillus paracasei DSM 13434 and Lpc-37, Ligilactobacillus salivarius Ls-33, Levilactobacillus brevis Lbr-35, Lactobacillus acidophilus La-14, and Bifidobacterium animalis subsp. lactis Bl-04, along with inulin 200 mg (107199).
• Rheumatoid arthritis (RA). Small clinical studies suggest that taking Lacticaseibacillus casei might be beneficial for RA. Details: Two small clinical studies in patients with RA show that taking L. casei 01 as 100 million colony-forming units daily for 8 weeks reduces tender and swollen joints and increases the number of patients who experience moderate symptom improvement when compared with placebo (90230,90297). However, one small clinical study in patients with moderate-to-severe RA shows that taking capsules containing freeze-dried strains of L. casei, Lactobacillus acidophilus, and Bifidobacterium bifidum daily for 8 weeks does not reduce RA severity, the number of tender or swollen joints, or joint pain when compared with placebo (95418).
• Rotaviral diarrhea. It is unclear if Lacticaseibacillus casei is beneficial for rotaviral diarrhea. Details: Although the World Gastroenterology Organization has not made a recommendation (98471), the European Society for Pediatric Infectious Diseases recommends probiotics in hospitalized children with diarrhea (98469) and the Infectious Disease Society of America (IDSA) recommends probiotics for the outpatient treatment of acute diarrhea (95388). However, these guidelines note that most evidence is low quality and is not specific to rotavirus infection. Furthermore, these guidelines were released prior to the publication of the most recent, high-quality studies showing no benefit with the use of certain probiotics (98427,98428). Research on the use of L. casei, specifically, for this purpose is lacking.
• Short bowel syndrome. Although there has been interest in using oral Lacticaseibacillus casei for short bowel syndrome, there is insufficient reliable information about the clinical effects of L. casei for this condition.
• Small intestinal bacterial overgrowth (SIBO). It is unclear if oral Lacticaseibacillus casei is beneficial for the treatment of SIBO. Details: A small clinical study in children with chronic diarrhea due to SIBO shows that taking a combination of lyophilized L. casei 1.5 grams and Lactobacillus acidophilus 1.5 grams by mouth twice daily for 21 days decreases average daily stools by 1.5, but does not improve other symptoms, when compared with placebo (91143). Disparate study findings may be due to many factors, including differences in patient populations evaluated and use of different probiotic formulations. More evidence is needed to rate Lacticaseibacillus casei for these uses.

(Read more about LACTICASEIBACILLUS CASEI)

POSSIBLY EFFECTIVE

• Antibiotic-associated diarrhea. Most research shows that oral Lactobacillus acidophilus, alone or in combination with other probiotics, seems to reduce the risk of antibiotic-associated diarrhea (AAD) in adults. Details: A meta-analysis of 18 clinical trials in hospitalized or outpatient adults shows that taking L. acidophilus alone or in combination with up to 8 other probiotic strains reduces the risk of AAD by 34% when compared with taking placebo (107635). One small clinical trial in elderly adults shows that AAD occurred in 17% of those taking L. acidophilus (Florajen Acidophilus) 20 billion colony-forming units (CFUs) three times daily, compared with 37% of those taking placebo (95400). A number of combination products have also demonstrated benefit for preventing AAD, including Bio-K+ Cl1285 which provides L. acidophilus CL1285, Lacticaseibacillus casei LBC80R, and Lacticaseibacillus rhamnosus CLR2 as 100 billion CFUs daily (25494,95402,95403); L. acidophilus and Bifidobacterium animalis subsp. lactis (90239); and Ecologic AAD which provides L. acidophilus NIZO 3678 and NIZO 3887, Lacticaseibacillus paracasei NIZO 3672, Lactiplantibacillus plantarum NIZO 3684, L. rhamnosus NIZO 3689, Ligilactobacillus salivarius NIZO 3675, Bifidobacterium bifidum NIZO 3804, Bifidobacterium animalis subsp. lactis NIZO 3680, and Enterococcus faecium NIZO 3886 (95405). However, some combination products have not demonstrated benefit. Clinical research shows that taking a combination of L. acidophilus and bifidobacteria or a combination of L. acidophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lactinex) is not beneficial (90231,90239,92255,95385). An additional large clinical trial in children aged 3 months and up shows that taking L. acidophilus in combination with other probiotics does not reduce the risk of antibiotic-associated diarrhea when compared with taking placebo, when the more stringent definition is considered excluding diarrhea of other etiologies. However, the risk of diarrhea of any etiology is reduced by 35%. The probiotic supplement provided a total of 10 billion CFUs of L. acidophilus W37, Bifidobacterium bifidum W23, Bifidobacterium animalis subsp. lactis W51, Lactobacillus acidophilus W55, Lacticaseibacillus paracasei W20, Lactiplantibacillus plantarum W62, Lacticaseibacillus rhamnosus W71, and Ligilactobacillus salivarius W24 daily from the first day of antibiotic treatment until 7 days after treatment ended (110969).
• Bacterial vaginosis. Most clinical research shows that intravaginal application of Lactobacillus acidophilus may be helpful for the treatment of bacterial vaginosis. It is unclear if oral L. acidophilus is beneficial for the treatment or prevention of bacterial vaginosis. Details: One clinical trial shows that intravaginal suppositories containing 100 million to 1 billion colony-forming units (CFUs) of L. acidophilus (Vivag, Pharma Vinci A/S) given twice daily for 6 days improve bacterial vaginosis resolution rates when compared with placebo (13177). Another clinical trial shows that using 1-2 vaginal tablets containing viable L. acidophilus 10 million CFUs and estriol 0.03 mg per tablet (Gynoflor, Medinova) daily for 6 days increases cure rates when compared with placebo (13176). However, using this product in combination with metronidazole 400 mg twice daily for 7 days does not improve outcomes when compared with metronidazole alone (90237). Preliminary clinical research in patients with clinically defined bacterial vaginosis shows that daily intravaginal application with a douche providing L. acidophilus 1 billion CFUs per mL for 6 days might have beneficial effects on the vaginal flora. When compared with 52.5% of patients with bacterial vaginosis based on bacterial flora at baseline, 7.5% met this criteria 14 days after treatment had been completed (111788). Oral L. acidophilus has also been evaluated. Preliminary clinical research shows that eating yogurt 125 mL daily enriched with L. acidophilus for 2 months might slightly decrease the incidence of recurrent bacterial vaginosis (1245). L. acidophilus has also been investigated in an oral formulation in combination with other probiotics. Clinical research in patients with bacterial vaginosis cured within the past 48 hours shows that taking a product containing L. acidophilus in combination with other probiotics results in recurrence of vaginosis in 18.3% of patients, a statistically significant reduction compared with 32.1% of those using placebo. The mean time to recurrence was approximately 23 days longer in patients taking the lactobacilli. The product contained L. acidophilus 1.08 billion CFUs along with Lactobacillus crispatus LMG S-29995 and Levilactobacillus brevis (Lactogyn, Vésale Pharma, Belgium), and was taken twice daily for 7 days and then once daily for up to an additional 120 days (110950).
• Helicobacter pylori. Oral Lactobacillus acidophilus, usually in combination with other probiotics, seems to improve H. pylori eradication when used along with standard therapies. It is unclear if heat-killed L. acidophilus is beneficial for H. pylori eradication. Details: A meta-analysis of clinical studies utilizing probiotic products containing L. acidophilus shows that these products can improve H. pylori eradication rates 1.14- to 1.24-fold when taken in combination with triple therapy consisting of a proton-pump inhibitor (PPI), clarithromycin, and amoxicillin. Based on these results, about 7-11 patients would need to be treated in order for one additional patient to achieve complete remission (95394). Only one of the trials in this analysis investigated L. acidophilus alone; an additional 8 used L. acidophilus in combination with other probiotics. Individual clinical trials have shown that a combination of L. acidophilus, Enterococcus faecalis, and Bacillus subtilis 30 million colony-forming units (CFUs) total, taken in three divided doses daily, from 2 weeks prior tol 2 weeks after triple therapy increases H. pylori eradication when compared with triple therapy alone (90248). In children, a combination of L. acidophilus (strain 5) 94 million CFUs and Bifidobacterium bifidum (strain 12) 8.6 million CFUs in combination with a PPI, clarithromycin, and amoxicillin or metronidazole has been used daily for 2 weeks, followed by the probiotics alone for an additional 4 weeks (90602). However, other individual clinical trials have shown that L. acidophilus in combination with Lacticaseibacillus rhamnosus, Bifidobacterium bifidum, and Streptococcus faecium may not improve eradication rates when taken with triple therapy consisting of furazolidone, tetracycline, and lansoprazole (90279). Also, taking L. acidophilus along with six other probiotics in conjunction with bismuth quadruple therapy does not seem to improve H. pylori eradication rates when compared with placebo and bismuth quadruple therapy (90291). Also, taking L. acidophilus and L. casei without any standard H. pylori therapy does not improve H. pylori eradication rates in adults (12766). Heat-killed L. acidophilus has also been investigated in adults with H. pylori. Taking a lyophilized and inactivated culture of L. acidophilus (Lacteol Fort) containing 5 billion cells, 3 times daily for 10 days, modestly increases the eradication rate in patients using triple therapy of rabeprazole, clarithromycin, and amoxicillin for 7 days (8562).
• Irritable bowel syndrome (IBS). Some research shows that oral live Lactobacillus acidophilus, taken alone or in combination with other probiotics, may be beneficial for IBS. The effects of non-viable, heat-killed L. acidophilus are unclear. Details: Clinical research in adults with IBS shows that taking L. acidophilus DDS-1 10 billion colony-forming units (CFUs) daily for 6 weeks modestly reduces the severity of abdominal pain when compared with placebo. Also, 52% of patients experienced a more than 30% reduction in pain severity, compared with 16% of those taking placebo. There were also improvements in abdominal distention and duration of pain; however, there were no changes in bowel habits (107581). A meta-analysis shows that taking L. acidophilus improves the rate of symptom relief and reduces bloating severity when compared with placebo. However, other symptoms were not improved (110866). L. acidophilus has also been examined in combination with other probiotics. One clinical study shows that taking a specific combination product (Visbiome, ExeGi Pharma) containing L. acidophilus and 7 other species as 450 billion CFUs daily in two divided doses for 8 weeks improves abdominal bloating, but not abdominal pain, flatulence, or number of stools, in patients with diarrhea-predominant IBS (IBS-D) (11379). Another clinical study in patients with IBS-D shows that taking a specific multi-species probiotic (NordBiotic, MBM Biotix) containing L. acidophilus LA120, Lacticaseibacillus rhamnosus LR110, Lacticaseibacillus paracasei LPC100, Lacticaseibacillus casei LC130, Lactiplantibacillus plantarum LP140, Bifidobacterium breve BB010, Bifidobacterium longum BL020, Bifidobacterium bifidum BF030, Bifidobacterium animalis subsp. lactis BL040, and Streptococcus thermophilus ST250 as 2.5 billion CFUs total twice daily for 8 weeks improves overall symptom severity, as well as pain severity, pain frequency, and quality of life, when compared with placebo. Symptom severity was rated as mild by approximately 60% of those taking the probiotic mixture, compared with 30% of those taking placebo (107516). A small clinical trial shows that taking L. acidophilus NCFM plus Lactobacillus helveticus Lafti L10 (Lallemand Health Solutions) 5 billion CFUs each daily for 8 weeks modestly reduces flatus and overall symptoms, but not abdominal pain or bloating, when compared with taking placebo (111785). However, other probiotic compounds containing L. acidophilus have not demonstrated benefit in most patients with IBS. These include L. acidophilus NCFM 10 billion CFUs daily for 12 weeks; L. acidophilus, L. paracasei, and Bifidobacterium animalis subsp. lactis BB-12 (Cultura) 13-20 billion CFUs daily for 6 months; or L. acidophilus CL1285, L. casei LBC80R, and L. rhamnosus CLR2 50 billion CFUs each daily for 3 months (90236,94696,94697,95365,99789). Further research is needed to determine which IBS subtype, if any, is most likely to benefit. Heat-killed L. acidophilus has also been investigated in patients with IBS. One clinical study shows that taking capsules containing heat-killed L. acidophilus (Lacteol Fort) 20 billion colony-forming units (CFUs) daily for 6 weeks improves abdominal pain, bloating, and number and quality of stools when compared with placebo (7744). Also, in patients with IBS-D, observational research has found that use of heat-killed L. acidophilus (Lacteol LB) two capsules daily for one month modestly reduces pain and bloating and improves quality of life. The average weekly number of stools decreased by approximately 4.75. Also, the number of patients with watery stools was reduced from 54% at baseline to 19% (107535).

POSSIBLY INEFFECTIVE

• Atopic disease. Oral Lactobacillus acidophilus does not seem to be beneficial for preventing atopic disease in children. Details: A meta-analysis of clinical research shows that administering L. acidophilus during pregnancy, when breastfeeding, or to newborn infants might actually increase the risk of atopic sensitization (90251). However, the number of studies included in this analysis was limited.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A preliminary clinical study shows that taking a specific probiotic product containing L. acidophilus 5 billion colony-forming units (CFUs), Lactobacillus delbrueckii subsp. bulgaricus 5 billion CFUs, and Bifidobacterium bifidum 20 billion CFUs (Trenev Trio/Healthy Trinity, Natren) twice daily along with minocycline once every evening for 12 weeks improves inflamed and non-inflamed acne lesions in 82% of patients, compared to only 67% of patients treated with either the probiotic combination or minocycline alone (90270).
• Acute respiratory distress syndrome (ARDS). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in premature infants shows that taking 6 billion CFUs of a combination of L. acidophilus NCDO 1748 and Bifidobacterium bifidum NCDO 2203 (UFC Inforan, Switzerland) from 7 days of age until 34 weeks postmenstrual age or discharge does not reduce the odds of ARDS when compared with a control group of infants not given these probiotics. The infants in this study were born at less than 32 weeks gestation and had a birthweight of less than 1500 grams (111794). This study is limited by the lack of randomization to treatment group; placement was based on year of birth.
• Allergic rhinitis (hay fever). It is unclear if oral Lactobacillus acidophilus is beneficial for allergic rhinitis prevention or treatment. Details: A small clinical trial in patients with perennial allergic rhinitis shows that taking heat-treated milk fermented with L. acidophilus L-92 100 mL daily for 8 weeks modestly reduces nasal symptoms and mucus, but not ocular symptoms, when compared with taking an acidified placebo milk. The milk provided approximately 30 billion L. acidophilus cells (25488). The effect of L. acidophilus as a probiotic is unclear from this study. Other clinical research shows that drinking 250 mL of fermented milk containing L. acidophilus La-5 5 billion colony-forming units (CFUs), Lacticaseibacillus rhamnosus GG 50 billion CFUs, and Bifidobacterium animalis subsp. lactis BB-12 50 billion CFUs from 36 weeks' gestation until 3 months postpartum does not reduce the incidence of allergic rhinitis in the child at 6 years of age when compared with placebo milk (96893).
• Asthma. It is unclear if oral Lactobacillus acidophilus can improve lung function in people with asthma. Details: A small clinical crossover study in patients with moderate asthma shows that consuming live active yogurt 225 grams, providing L. acidophilus 760 million colony-forming units (CFUs) per gram, twice daily for 1 month does not affect measures of lung function when compared with yogurt not containing L. acidophilus. All yogurt contained Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (1244).
• Atopic dermatitis (eczema). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of the available clinical research shows that intake of lactobacilli and bifidobacteria-based probiotics during gestation, followed by giving the probiotic to the newborn for the first 2-6 months of life, reduces the risk of developing atopic dermatitis by 40% over the next 6-24 months when compared with placebo, regardless of family history of atopy. However, only four of 10 studies included in the analysis used L. acidophilus as part of the probiotic combination; the results from these individual, small studies support the overall findings of the meta-analysis (107503). Some clinical research also shows that supplementation with 250 mL of fermented milk containing L. acidophilus La-5, Lacticaseibacillus rhamnosus GG, and Bifidobacterium animalis subsp. lactis BB-12 starting at 36 weeks' gestation and continuing until 3 months' postpartum, without supplementation in the infant, reduces the overall occurrence of atopic dermatitis in the child at 2 years of age. However, at 6 years of age, the effect appears to be inconclusive (96893). In children ages 1-3 years with moderate to severe atopic dermatitis, taking 5 billion colony-forming units (CFUs) of a combination of L. acidophilus DDS-1 and Bifidobacterium animalis subsp. lactis UABLA-12 along with fructo-oligosaccharides (FOS) (DDS Junior) twice daily for 8 weeks modestly reduces symptom severity and the need for topical corticosteroids when compared with placebo (110995).
• Bronchopulmonary dysplasia. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One large observational study in premature infants suggests that taking L. acidophilus 1 to 3 billion CFUs with Bifidobacterium longum subsp. infantis during the first month of life for the prevention of necrotizing enterocolitis was not associated with a reduced risk of bronchopulmonary dysplasia. The infants in this study were born between 22-29 weeks gestation and had a birthweight of less than 1500 grams (111771).
• Cancer. Although there has been interest in using oral Lactobacillus acidophilus for cancer prevention or treatment, there is insufficient reliable information about the clinical effects of L. acidophilus for this condition.
• Canker sores. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A systematic review and meta-analysis of mainly small and preliminary clinical trials shows that taking lactobacilli probiotics has a small effect on pain from canker sores. However, the dose and duration of probiotic and the specific species, as well as endpoints and results from individual studies, are mixed. One small study shows that taking a combination of L. acidophilus, Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, and Bifidobacterium animalis subsp. lactis reduces pain, but not the number of lesions or healing time, when compared with placebo. Another study shows that using lozenges providing inulin 0.13 gram along with L. acidophilus and B. animalis subsp. lactis 1.5 billion colony-forming units each reduces pain, but does not affect ulcer size or healing, when compared with Oracure gel (105146). Many of the individual studies may have been underpowered to detect a difference between groups.
• Cholestasis. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in premature infants shows that the risk of developing cholestasis is reduced from 22% to 6% in those given a blend of L. acidophilus, bifidobacteria, and Enterococcus faecalis (Peifeikang powder, Shanghai Xinyi Pharmaceutical Company) at least 5 million colony-forming units three times daily, from birth until implementation of total parenteral nutrition, when compared with infants not given this powder. In the infants that developed cholestasis, the severity was reduced, resulting in a reduction in the rate of cholestatic liver injury, feeding intolerance, and necrotizing enterocolitis. The number of days to reach full enteral feeding, days to normal weight gain, and days of hospitalization were reduced by approximately 2.8, 2.1, and 1.7 days, respectively (103448).
• Clostridioides difficile infection. It is unclear if oral Lactobacillus acidophilus is beneficial for preventing C. difficile occurrence or recurrence. Details: Current guidelines from the Infectious Diseases Society of America (IDSA) state that there is insufficient information to recommend administration of probiotics for the primary prevention of C. difficile-associated diarrhea (107538). Evidence from clinical and observational research investigating the effect of L. acidophilus on C. difficile occurrence or recurrence is weak. Most studies use this species in combination with one or more additional probiotic species, including as Bio-K+ CI1285, containing L. acidophilus CL1285 and L. casei LBC80R, and as Bio-K+ 50 Billion, containing L. acidophilus CL1285, Lacticaseibacillus casei LBC80R, and Lacticaseibacillus rhamnosus CLR2 (25494,90231,90934,95369,95403,107529). Observational research has found that providing the Bio-K+ 50 Billion product as 50-100 billion colony-forming units (CFUs) daily for 5 days to patients who are on antibiotics for at least 2 days reduces the hospital-wide incidence of C. difficile by approximately 40%. The incidence rate was decreased by at least 50% in the highest risk individuals taking this combination (107529).
• Colic. Oral inactivated Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study in infants with colic shows that giving a specific multi-ingredient product (Colimil Plus, Milte Italia SPA) containing inactivated L. acidophilus 1 billion colony-forming units, lemon balm 65 mg, and German chamomile 9 mg twice daily for 4 weeks reduces crying time similarly to Limosilactobacillus reuteri DSM 17938 100 million CFUs daily (96278). It is unclear how L. acidophilus compares with no treatment.
• Common cold. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in school children shows that taking a combination of L. acidophilus and Bifidobacterium bifidum (Infloran, Berna) 1 billion colony-forming units each twice daily for 3 months reduces the absolute percentage of school absence due to cold symptoms by 30% when compared with placebo (90286).
• Constipation. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that stool frequency is increased and symptoms of functional constipation in adults are improved with the use of a specific combination product (Hexbio) providing L. acidophilus, Lacticaseibacillus casei, Lactobacillus delbrueckii subsp. lactis, Bifidobacterium bifidum, Bifidobacterium longum, and Bifidobacterium longum subsp. infantis 30 billion colony-forming units (CFUs) twice daily for 7 days (90266). However, most other probiotic compounds containing L. acidophilus have not demonstrated benefit in most patients with constipation. One small clinical trial shows that taking yogurt 180 mL providing L. acidophilus NCFM, Bifidobacterium animalis subsp. lactis HN019, and polydextrose (Litesse) daily for 2 weeks modestly improves clinical response and reduces transit time when compared with taking a control yogurt. However, there was no effect on the number of daily bowel movements (90275). Other studies show that taking Lactobacillus acidophilus DDS-1 6.6 billion CFUs daily for 4 weeks in combination with Bifidobacterium longum UABl-14, Bifidobacterium animalis subsp. lactis UABla-12, Bifidobacterium bifidum UABb-10, and fructo-oligosaccharides (FOS) 7 mg does not improve symptoms of constipation when compared with a placebo providing FOS (110970). Also, there was a general lack of support for symptom improvement following the intake of Lactobacillus acidophilus NCFM 10 billion CFUs daily with Lacticaseibacillus paracasei Lpc-37 and Bifidobacterium animalis subsp. lactis strains Bl-04, Bi-07, and HN019 daily for 2 weeks (110979).
• Critical illness (trauma). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in critically ill, hospitalized adults shows that taking L. acidophilus LA-5 1.75 billion colony-forming units (CFUs), Lactiplantibacillus plantarum 500 million CFUs, Bifidobacterium animalis subsp. lactis BB12 1.75 billion CFUs, and Saccharomyces boulardii 1.5 billion CFUs twice daily for 15 days modestly reduces the risk of sepsis, as well as the length of stay in the ICU and hospital, when compared with placebo (107524).
• Denture stomatitis. Although there has been interest in using oral Lactobacillus acidophilus for denture stomatitis, there is insufficient reliable information about the clinical effects of L. acidophilus for this condition.
• Depression. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with major depression shows that taking L. acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum daily for 8 weeks reduces symptoms of depression measured on the Beck Depression Inventory (BDI) when compared with placebo (99780). However, the validity of the results from this study is limited by incomplete reporting. For example, patient baseline BDI scores were not reported.
• Diabetes. Oral Lactobacillus acidophilus in combination with other probiotic species seems to be beneficial for the treatment of gestational diabetes, although it is unclear if it is beneficial for treatment of type 1 or type 2 diabetes. Oral L. acidophilus is unlikely to be beneficial for the prevention of gestational diabetes. Details: Although some individual studies disagree, meta-analyses of clinical research in patients with gestational diabetes show that taking probiotics, most often L. acidophilus in combination with other species, improves glycemic indices such as fasting blood glucose and insulin sensitivity when compared with placebo (102288,104156). Also, one meta-analysis of clinical research shows that taking probiotics specifically containing L. acidophilus in combination with other species modestly improves these glycemic indices, as well as levels of total cholesterol and triglycerides, but not low-density lipoprotein (LDL) or high-density lipoprotein (HDL) cholesterol (111796). Some doses used in available studies include a combination of freeze-dried L. acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum each as 2 billion colony-forming units (CFUs) per gram daily for 6 weeks (95416,98430), a total of 4 billion CFUs of a combination of L. acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12, Streptococcus thermophilus STY-31, and Lactobacillus delbrueckii subsp. bulgaricus LBY-27 for 8 weeks starting at 24-28 weeks' gestation (96892), and a specific product containing L. acidophilus and 7 other probiotics (Visbiome, ExeGi Pharma) as a total of 112.5 billion CFUs twice daily for 8 weeks (107549). Meta-analyses in patients with gestational diabetes show that taking probiotics such as L. acidophilus does not reduce the risk for caesarean section birth, neonatal hypoglycemia, large for gestational age birth, or hypertensive disorders such as pregnancy-induced hypertension, pre-eclampsia, or eclampsia (102288,104156,111796). However, one meta-analysis of clinical research shows that taking probiotics specifically containing L. acidophilus modestly reduces neonatal birth weight, but not maternal weight gain (111796). Taking L. acidophilus does not seem to be effective for PREVENTING gestational diabetes. A large clinical trial shows that taking L. acidophilus LA1 7.5 billion CFUs, Bifidobacterium longum sp54 cs 1.5 billion CFUs, and Bifidobacterium bifidum sp9 cs 6 billion CFUs daily from 14-24 weeks' gestation does not reduce the incidence of gestational diabetes when compared with taking placebo (107520). Research on the use of L. acidophilus for type 2 diabetes is mixed. Taking a combination of L. acidophilus, Bifidobacterium bifidum, and Streptococcus thermophilus daily for 12 weeks does not reduce levels of fasting blood glucose or glycated hemoglobin (HbA1c) when compared with placebo (107521). One clinical study shows that taking L. acidophilus along with six other probiotic strains (Familact) daily for 6 weeks reduces fasting blood glucose, but does not affect plasma insulin, when compared with placebo (99790). A small clinical trial shows that taking fermented goat milk 120 grams containing one billion CFUs each of L. acidophilus La-5 and Bifidobacterium animalis subsp. lactis BB-12 daily for 6 weeks modestly reduces levels of HbA1c and low-density lipoprotein (LDL) cholesterol, but not fasting blood glucose or insulin resistance, when compared with conventional fermented milk containing Streptococcus thermophilus TA-40 (110973). However, other clinical research shows that taking L. acidophilus 1 billion CFUs, along with Lacticaseibacillus rhamnosus, Bacillus coagulans GanedenBC30 (GBI-30, 6086), and fructo-oligosaccharides 500 mg daily for 12 weeks modestly reduces fasting blood glucose and insulin and improves measures of insulin resistance when compared with placebo (107731). Another clinical trial shows that taking yogurt 200 grams daily containing L. acidophilus 4.65 million CFUs per gram along with Bifidobacterium animalis subsp. lactis modestly reduces levels of HbA1c, triglyceride, and LDL cholesterol, but not fasting glucose, when compared with a placebo yogurt (111798). A combination probiotic containing L. acidophilus has also been evaluated in children 2-12 years of age with new-onset type 1 diabetes. One clinical study shows that taking a specific combination product (Visbiome, ExeGi Pharma) providing 112.5 billion CFUs daily for 3 months modestly decreases HbA1c and insulin requirements when compared with placebo. Also, about three times as many children achieved remission, defined as insulin requirements of less than 0.5 U/kg daily and HbA1c less than 7%. However, C-peptide levels and the maintenance of residual pancreatic beta-cell function were not affected when compared with placebo (107497).
• Diabetic nephropathy. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with diabetic nephropathy not taking antidiabetes drugs shows that taking a combination of L. acidophilus, Bifidobacterium bifidum, and Streptococcus thermophilus daily for 12 weeks modestly reduces the ratio of microalbuminuria/creatinine (mAlb/Cr), a marker of kidney damage, when compared with placebo. However, there was no effect on the estimated glomerular filtration rate (eGFR) (107521).
• Diarrhea. Oral heat-killed L. acidophilus seems to reduce the duration of diarrhea in adults and children. Oral live L. acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in children with dysentery being treated with ceftriaxone shows that taking a specific combination probiotic sachet (Kidilact, Zisttakhmir Company) containing live L. acidophilus, Lacticaseibacillus casei, Lacticaseibacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus, Bifidobacterium longum subsp. infantis, Bifidobacterium breve, and Streptococcus thermophilus daily for 5 days modestly reduces the duration of diarrhea, hospitalization, and blood in diarrhea when compared with control (102417). Heat-killed L. acidophilus has also been investigated for the treatment of diarrhea. A meta-analysis of four small clinical studies in infants and children ages 1 month to 4 years shows that taking heat-killed L. acidophilus LB 20-30 billion colony-forming units (CFUs) daily for up to 5 days along with oral or intravenous rehydration therapy can modestly reduce the duration of diarrhea, primarily of non-rotaviral origin (90295). Also, preliminary clinical research in patients with functional chronic diarrhea shows that taking heat-killed L. acidophilus LB (Lacteol Fort, Laboratoire du Lacteol du Dr Boucard) as two capsules twice daily for a total of 20 billion cells daily for 4 weeks reduces daily stool frequency by 3.5, compared with a reduction of 1.2 in patients taking five chewable capsules three times daily of an unspecified strain of L. acidophilus (Lacidophilin, Tai Ge Pharma Ltd). Stool consistency, pain, distention, and total efficacy, defined as a decrease in mean symptoms by at least 40%, were also further improved in patients taking the heat-killed product (107537). However, other clinical research in children ages 6 months to 12 years hospitalized with acute diarrhea shows that taking 15 billion heat-killed L. acidophilus (Lactrol, Raptakos) cells daily for 3 days along with oral rehydration solution (ORS) does not have beneficial effects on duration of diarrhea, frequency of stools, or length of hospital stay, when compared with ORS alone (111789). The European Society for Pediatric Infectious Diseases recommends probiotics in hospitalized children with diarrhea (98469) and the Infectious Disease Society of America (IDSA) recommends probiotics for the outpatient treatment of acute diarrhea (95388) However, L. acidophilus is not a specific focus of the guidelines and most evidence is low quality.
• Generalized anxiety disorder (GAD). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in patients newly diagnosed with GAD shows that taking sertraline 25 mg plus probiotics daily for 8 weeks may modestly reduce some symptoms of anxiety when compared with sertraline alone. However, the reduction in anxiety score was small and change was not consistent between rating scales. Also, the quality of life was not improved. The probiotics provided a total of 18 billion colony-forming units of L. acidophilus, Bifidobacterium bifidum, Bifidobacterium longum, and Bifidobacterium animalis subsp. lactis (110977).
• Hepatic encephalopathy. Although there has been interest in using oral Lactobacillus acidophilus for hepatic encephalopathy, there is insufficient reliable information about the clinical effects of L. acidophilus for this condition.
• HIV/AIDS. Although there has been interest in using oral Lactobacillus acidophilus for HIV/AIDS, there is insufficient reliable information about the clinical effects of L. acidophilus for this condition.
• Hypercholesterolemia. It is unclear if oral Lactobacillus acidophilus is beneficial for lowering cholesterol levels; the available research is conflicting. Details: Two meta-analyses of clinical research show that taking fermented milk products containing L. acidophilus can reduce total cholesterol by about 14-19 mg/dL in adults with or without hypercholesterolemia. However, the effect of L. acidophilus on both total and LDL cholesterol levels is conflicting from available research (95396,95397,95399). Clinical trials included in these meta-analyses evaluated patients with hypercholesterolemia, type 2 diabetes, nonalcoholic fatty liver disease (NAFLD), metabolic syndrome, and others. Taking L. acidophilus does not appear to improve high-density lipoprotein (HDL) cholesterol or triglyceride levels (95396,95397,95399). Doses used in some studies have included fermented milk products providing L. acidophilus 39 million to 2 billion CFUs daily, alone or along with other probiotic species, for up to 6 weeks (95396). One small clinical trial in patients with hypercholesterolemia shows that taking L. acidophilus LA-1 60 billion colony-forming units (CFUs) three times daily for 6 weeks does not affect serum lipids when compared with taking placebo (111791). A meta-analysis of nine small to moderate-sized clinical studies shows that taking a combination of L. acidophilus and Bifidobacterium animalis subsp. lactis reduces levels of total cholesterol when compared with placebo (107591). However, it is unclear if this is due to L. acidophilus, Bifidobacterium animalis subsp. lactis, or their combination.
• Hypertension. Although there has been interest in using oral Lactobacillus acidophilus for hypertension, there is insufficient reliable information about the clinical effects of L. acidophilus for this condition.
• Inflammatory bowel disease (IBD). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small preliminary clinical trial in patients with collagenous colitis shows that taking 10 billion colony-forming units each of L. acidophilus LA-5 and Bifidobacterium longum subsp. lactis BB-12 twice daily for 12 weeks does not increase the proportion of patients with a reduction in weekly bowel frequency of at least 50% when compared with placebo. Also, there was no effect of this combination on stool consistency or abdominal symptoms. However, there were some modest benefits when compared with baseline (110999). This study was small and may have been underpowered to detect differences.
• Intraventricular hemorrhage. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in premature infants shows that taking 6 billion CFUs of a combination of L. acidophilus NCDO 1748 and Bifidobacterium bifidum NCDO 2203 (UFC Inforan, Switzerland) from 7 days of age until 34 weeks postmenstrual age or discharge does not reduce the odds of intraventricular hemorrhage when compared with a control group of infants not given these probiotics. The infants in this study were born at less than 32 weeks gestation and had a birthweight of less than 1500 grams (111794). This study is limited by the lack of randomization to treatment group; placement was based on year of birth.
• Lactose intolerance. It is unclear if oral Lactobacillus acidophilus is beneficial for lactose intolerance. Details: One small clinical trial shows that consuming 400 mL of a non-fermented milk product containing L. acidophilus 530 million colony-forming units (CFUs)/mL daily does not reduce symptoms of lactose intolerance or hydrogen breath test results when compared with milk without L. acidophilus (16737). Another small preliminary clinical trial shows that taking L. acidophilus BG2FO4 10 billion CFUs twice daily for 7 days does not reduce lactose-induced gastrointestinal symptoms or improve lactose digestion based on breath hydrogen when compared with baseline (111783). However, another clinical trial shows that adding various L. acidophilus strains 800 million to 1 billion CFUs/mL to non-fermented milk improves hydrogen breath tests in patients with lactose intolerance (16738).
• Lyme disease. Although there has been interest in using oral Lactobacillus acidophilus for Lyme disease, there is insufficient reliable information about the clinical effects of L. acidophilus for this condition.
• Metabolic syndrome. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in elderly patients with metabolic syndrome shows that taking a combination of L. acidophilus PBS066-DSM 24,936, Lactiplantibacillus plantarum PBS067-DSM 24,937, and Limosilactobacillus reuteri PBS072-DSM 25,175 as 2 billion colony-forming units (CFUs) each, with inulin and fructo-oligosaccharides daily for 60 days, reduces the number of patients diagnosed with metabolic syndrome by 23%, compared with a 10% reduction in those taking placebo. In the probiotic group, there were modest improvements in waist circumference and levels of fasting plasma insulin, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, and inflammatory mediators when compared with placebo. However, there were no significant differences between groups for fasting blood glucose or blood pressure. All patients in this study were on a Mediterranean-like standard diet (107560).
• Necrotizing enterocolitis (NEC). It is unclear if oral Lactobacillus acidophilus is beneficial or safe for NEC prevention. Details: Most meta-analyses of clinical research show that giving lactobacilli enterally reduces the risk of NEC and/or severe NEC in preterm, mainly very low birth weight (VLBW), infants. Some meta-analyses support the use of lactobacilli in combination with bifidobacteria, as opposed to lactobacilli alone for reducing the risk of NEC. However, only a small number of the individual studies included in these analyses have investigated the effects of L. acidophilus, which was used as part of a combination probiotic and/or prebiotic product in all cases (95344,95351,103437,103445,104157,105162,105164). Also, guidance among regulatory agencies and clinical organizations varies with respect to the use of probiotics in very low birth weight infants under 1000 grams. The US Food and Drug Administration (FDA) warns that preterm infants given probiotics are at risk of serious infections caused by the bacteria or fungi contained in probiotics due to cases reported in this group of infants (111610). Also, The American Academy of Pediatrics does not support the routine administration of probiotics to preterm infants, particularly those with a birth weight below 1000 grams, due to conflicting data on safety and efficacy and potential for harm in this vulnerable population (111608). The Canadian Paediatric Society, the American Gastroenterological Association, and the European Society for Paediatric Gastroenterology, Hepatology and Nutrition state that probiotic combinations may be of benefit in reducing the incidence of NEC in preterm neonates over 1000 grams. However, L. acidophilus is not specifically recommended (103003,111609,111611).
• Nonalcoholic fatty liver disease (NAFLD). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In children with NAFLD, clinical research shows that taking a specific combination product (Prokid, Gostaresh Milad Pouya Company) containing L. acidophilus ATCC B3208 3 billion colony-forming units (CFUs), Lacticaseibacillus rhamnosus DSMZ 21690 2 billion CFUs, Bifidobacterium animalis subsp. lactis DSMZ 32269 6 billion CFUs, and Bifidobacterium bifidum ATCC SD6576 2 billion CFUs daily for 12 weeks normalizes liver sonography findings in 53% of children, compared with 17% of those taking placebo. In addition, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are reduced by 30% and 25%, respectively. There was no effect on body mass index or blood lipids when compared with placebo (105156). Another clinical trial shows that taking two sachets daily for 3 months of a specific combination product (VSL#3) containing L. acidophilus and other probiotics modestly decreases triglyceride levels and liver enzymes when compared with taking placebo. However, there was no change in body mass index or most glycemic or lipid parameters (111009). However, taking L. acidophilus in combination with other probiotics does not seem to be beneficial in adults with NAFLD. Clinical research shows that taking yogurt 100 grams, containing L. acidophilus La-5 and Bifidobacterium animalis subsp. lactis Bb-12 40 million CFUs and vitamin D 1000 IU, daily for 3 months does not improve fasting blood glucose levels, insulin levels, blood pressure, or anthropometric indices when compared with unfortified yogurt (105174). Also, a small clinical trial shows that taking a combination of L. acidophilus BCMC 12,130, Lacticaseibacillus casei BCMC 12,313, Lactobacillus delbrueckii subsp. lactis BCMC 12,451, Bifidobacterium bifidum BCMC 02290, Bifidobacterium longum subsp. infantis BCMC 02129, and Bifidobacterium longum BCMC 02120 30 billion colony-forming units twice daily for 6 months has no beneficial effects on hepatic steatosis or fibrosis or on levels of liver enzymes, blood lipids, or fasting glucose, when compared with placebo (107523).
• Nonalcoholic steatohepatitis (NASH). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in patients with NASH shows that taking 1 billion colony-forming units each of L. acidophilus ATCC SD5221 and Bifidobacterium animalis subsp. lactis HN019 daily for 6 months does not have beneficial effects on severity of liver fibrosis or steatosis, metabolic markers, or inflammation when compared with taking placebo. The effect of this combination on liver enzymes was mixed (111797).
• Obesity. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In combination with Bifidobacterium animalis subsp. lactis BS01, taking L. acidophilus LA02 2 billion colony-forming units (CFUs) daily for 6 weeks does not reduce body weight or body fat when compared with placebo in young, healthy females, only some of whom were overweight (103438). However, another clinical study shows that taking 50 billion CFUs of a specific combination of L. acidophilus, Lactiplantibacillus plantarum, Bifidobacterium bifidum, and B. animalis subsp. lactis (Lab4P) for 24 weeks reduces body weight by an additional 1.3 kg more than placebo (103439).
• Polycystic ovary syndrome (PCOS). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In patients with PCOS, clinical research shows that taking a combination of L. acidophilus T16 (IBRC-M10785), Lacticaseibacillus casei T2 (IBRC-M10783), and Bifidobacterium bifidum T1 (IBRC-M10771) 2 billion colony-forming units each, plus inulin 800 mg, daily for 12 weeks modestly reduces serum insulin and triglyceride levels and improves insulin resistance and insulin sensitivity when compared with placebo. However, it does not alter cholesterol or fasting glucose levels (105159). Another clinical trial shows that 31.3% of patients with PCOS taking L. acidophilus in combination with other probiotics daily for 6 months had regular menstrual cycles compared with 12.5% of those taking placebo. There were also modest improvements in testosterone levels and waist circumference, but not other hormones, insulin resistance, body weight, or most measures of quality of life. The product provided Lactobacillus acidophilus UBLA-34 2 billion CFUs along with Bifidobacterium bifidum UBBB-55, Lactiplantibacillus plantarum UBLP-40, Lacticaseibacillus casei UBLC-42, Limosilactobacillus fermentum UBLF-31, Lacticaseibacillus rhamnosus UBLR-58, Limosilactobacillus reuteri UBLRu-87, and fructo-oligosaccharides (FOS) daily for 2 months and then twice daily for 4 months. All patients also underwent dietary and lifestyle changes (110974).
• Postoperative infection. Although there has been interest in using oral Lactobacillus acidophilus for preventing postoperative infections, there is insufficient reliable information about the clinical effects of lactobacillus for this purpose.
• Pouchitis. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Continuous oral treatment for one year with a specific concentrated formulation of L. acidophilus and other probiotics (Visbiome, ExeGi Pharma) as 6 grams (300-500 billion live bacteria per gram), daily for up 12 months seems to maintain remission of pouchitis in 85% of patients (6087,12769). Also, one small clinical study shows that taking a specific product (Trilac, Allergon AB) containing L. acidophilus 600 million colony-forming units (CFUs) per capsule, Lactobacillus delbrueckii subsp. bulgaricus 400 million CFUs per capsule, and Bifidobacterium bifidum 600 million CFUs per capsule, taken in doses of two capsules three times daily for 9 months, can reduce pouchitis severity and the number of patients experiencing pouchitis when compared to baseline (90296). The validity of these findings is limited by the lack of a comparator group.
• Pregnancy-induced nausea and vomiting. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small preliminary clinical trial shows that taking probiotics during pregnancy reduces the severity and duration of nausea and vomiting by 16% to 54%. There was also a small benefit on stool hardness. A specific probiotic (Probiotics 10, Nature's Bounty) was taken as 2 capsules daily for two back-to-back cycles of six days with probiotics and two days without. Each capsule contained a total of 10 billion colony-forming units (CFUs) of L. acidophilus La-14, Lactiplantibacillus plantarum 299v and DSM 15312, Lactobacillus delbrueckii subsp. bulgaricus Lb-87, Lacticaseibacillus paracasei DSM 13434 and Lpc-37, Ligilactobacillus salivarius Ls-33, Levilactobacillus brevis Lbr-35, Lacticaseibacillus casei Lc-11, and Bifidobacterium animalis subsp. lactis Bl-04, along with inulin 200 mg (107199).
• Prematurity. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In premature infants, clinical research shows that taking a blend of L. acidophilus, bifidobacteria, and Enterococcus faecalis (Peifeikang powder, Shanghai Xinyi Pharmaceutical Company), at least 5 million colony-forming units (CFUs) three times daily from birth until implementation of total parenteral nutrition, reduces the rate of development of extrauterine growth retardation from 15% to 8% when compared with those not receiving this blend (103448). Other preliminary clinical research in premature infants shows that taking 6 billion CFUs of a combination of L. acidophilus NCDO 1748 and Bifidobacterium bifidum NCDO 2203 (UFC Inforan, Switzerland) from 7 days of age until 34 weeks postmenstrual age or discharge reduces the odds of neurodevelopment impairment at 24 months corrected age by 70% when compared with a control group of infants not given these probiotics. The odds of having moderate to severe impairment were also reduced. The infants in this study were born at less than 32 weeks gestation and had a birthweight of less than 1500 grams (111794). This study is limited by the lack of randomization to treatment group; placement was based on year of birth. Observational research has also been conducted. One large observational study in infants fed strictly human milk, but not strictly formula or a combination, suggests that taking L. acidophilus 1 to 3 billion CFUs with Bifidobacterium longum subsp. infantis during the first month of life for the prevention of necrotizing enterocolitis was associated with a modest increased weight gain velocity. The infants in this study were born between 22-29 weeks gestation and had a birthweight of less than 1500 grams (111771).
• Psoriasis. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with psoriasis shows that taking a mixture of probiotics for 8 weeks modestly improves overall symptoms and feelings of depression when compared with placebo. The percentage of patients achieving at least a 50% or 75% reduction in overall symptom score was 40% and 24%, respectively, in those taking the probiotic mixture, compared with 16% and 8% of those taking placebo. Each probiotic capsule was used twice daily and provided a total daily dose of 2.6 billion colony-forming units (CFUs) of L. acidophilus, Bifidobacterium bifidum, Bifidobacterium animalis subsp. lactis, and Bifidobacterium longum (107498).
• Radiation-induced diarrhea. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with cervical cancer receiving radiotherapy with or without chemotherapy shows that taking a specific product (Biogurt, Fame Pharmaceuticals) containing L. acidophilus LA-5 and Bifidobacterium animalis subsp. lactis BB-12 as 1.75 billion lyophilized colony-forming units (CFUs) as a capsule three times daily throughout treatment reduces the risk of diarrhea by 28% when compared with placebo. The treatment group also used less loperamide (102285). Another small clinical trial in patients undergoing pelvic radiotherapy with weekly cisplatin shows that taking L. acidophilus and Bifidobacterium bifidum (Infloran, Laboratio Farmaceutico SIT) as 1 billion CFUs each, twice daily from seven days before starting radiotherapy and continuing during radiotherapy, reduces the incidence of moderate to severe diarrhea and the need for antidiarrheal medication when compared with placebo. Moderate to severe diarrhea occurred in 9% of patients using the probiotics, compared with 45% of those taking placebo (107580).
• Respiratory tract infections. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in children ages 3-5 years who attend daycare centers shows that taking a combination milk product containing 5 billion colony-forming units (CFUs) each of L. acidophilus and Bifidobacterium animalis (HOWARU Protect, Danisco) reduces the risk of experiencing fever, cough, and rhinorrhea by 45% when compared with placebo. Patients taking this combination experienced an average 2-day shorter duration of symptoms and were significantly less likely to use an antibiotic for their symptoms. Patients who took L. acidophilus without bifidobacterium also had a reduction in fever, cough, and use of antibiotics, but not rhinorrhea (16847). In healthy children aged 3-10 years, clinical research shows that taking 12.5 billion CFUs daily of a specific combination of L. acidophilus CUL21 and CUL60, Bifidobacterium bifidum CUL20, Bifidobacterium animalis subsp. lactis CUL34 (Lab4), and vitamin C 50 mg daily reduces the risk of cough by 16% and sore throat by 20%, and modestly reduces school absenteeism and antibiotic use when compared with placebo. However, nasal symptoms, fever, and wheezing were not reduced (106943). A different combination product containing L. acidophilus DDS-1 1 billion CFUs and B. animalis subsp. lactis UABLA-12 4 billion CFUs (Up4-Junior, UAS Laboratories) with fructo-oligosaccharides 50 mg has also been evaluated. Clinical research in children 3-12 years of age with a sick household member shows that taking this product daily for 2 weeks modestly shortens the duration of respiratory infections, but does not reduce the risk of developing an infection, when compared with placebo (98439). In overweight adults or adults with obesity, taking 50 billion CFUs of a specific combination of L. acidophilus, Lactiplantibacillus plantarum, B. bifidum, and B. animalis subsp. lactis (Lab4P) for 24 weeks reduces the overall likelihood of having upper respiratory tract infection symptoms, such as sneezing, cough, and blocked nose, by approximately 40% when compared with placebo (103439).
• Retinopathy of prematurity. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in premature infants shows that taking 6 billion CFUs of a combination of L. acidophilus NCDO 1748 and Bifidobacterium bifidum NCDO 2203 (UFC Inforan, Switzerland) from 7 days of age until 34 weeks postmenstrual age or discharge does not reduce the odds of retinopathy of prematurity when compared with a control group of infants not given these probiotics. The infants in this study were born at less than 32 weeks gestation and had a birthweight of less than 1500 grams (111794). This study is limited by the lack of randomization to treatment group; placement was based on year of birth. Also, one large observational study in premature infants suggests that taking L. acidophilus 1 to 3 billion CFUs with Bifidobacterium longum subsp. infantis during the first month of life for the prevention of necrotizing enterocolitis was not associated with a reduced risk of retinopathy of prematurity. The infants in this study were born between 22-29 weeks gestation and had a birthweight of less than 1500 grams (111771).
• Rheumatoid arthritis (RA). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study in patients with moderate-to-severe RA shows that taking capsules containing freeze-dried strains of L. acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum daily for 8 weeks does not improve RA severity, the number of tender or swollen joints, or joint pain when compared with placebo (95418).
• Rotaviral diarrhea. It is unclear if oral Lactobacillus acidophilus is beneficial for rotaviral diarrhea. Details: One preliminary clinical study shows that taking a combination of L. acidophilus AD031 2 billion colony-forming units (CFUs) and Bifidobacterium longum BORI 20 billion CFUs twice daily for 3 days reduces the duration of rotaviral diarrhea by an average of 3 days when compared with placebo (95334). However, one clinical study using a lower dose and different strain of L. acidophilus (La-14) 200 million CFUs twice daily for 5 days shows that this regimen does not reduce the duration of watery diarrhea or affect the viral load in children aged 9 months to 5 years with confirmed norovirus or rotavirus infection (96887). A small clinical study shows that heat-killed L. acidophilus LB 20-30 billion cells daily for up to 4 days can modestly reduce the duration of diarrhea in infants and children, some of which had confirmed rotavirus (90295).
• Sepsis. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in premature infants shows that taking 6 billion CFUs of a combination of L. acidophilus NCDO 1748 with Bifidobacterium bifidum NCDO 2203 (UFC Inforan, Switzerland) from 7 days of age until 34 weeks postmenstrual age or discharge reduces the odds of late onset sepsis by 55% when compared with a control group of infants not given these probiotics. The infants in this study were born at less than 32 weeks gestation and had a birthweight of less than 1500 grams (111794). This study is limited by the lack of randomization to treatment group; placement was based on year of birth. One large observational study in infants fed a mix of human milk and formula, but not strictly human milk or formula, suggests that taking L. acidophilus 1 to 3 billion CFUs with Bifidobacterium longum subsp. infantis during the first month of life for the prevention of necrotizing enterocolitis was associated with a 31% reduction in the development of clinical sepsis. The infants in this study were born between 22-29 weeks gestation and had a birthweight of less than 1500 grams (111771).
• Short bowel syndrome. Although there has been interest in using oral Lactobacillus acidophilus for short bowel syndrome, there is insufficient reliable information about the clinical effects of lactobacillus for this condition.
• Small intestinal bacterial overgrowth (SIBO). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in children with chronic diarrhea due to SIBO shows that taking a combination of lyophilized L. acidophilus 1.5 grams and Lacticaseibacillus casei 1.5 grams by mouth twice daily for 21 days decreases average daily stools by 1.5, but does not improve other symptoms, when compared with placebo (91143). Also, one preliminary clinical study shows that taking a total of 2 billion CFUs of L. acidophilus and Lacticaseibacillus rhamnosus (Lacidofil) daily for 4 weeks does not prevent the development of SIBO in children that started treatment with omeprazole 20 mg daily for epigastric pain (90262).
• Travelers' diarrhea. It is unclear if oral Lactobacillus acidophilus is beneficial for the prevention of travelers' diarrhea. Details: A meta-analysis which included three clinical studies evaluating the use of L. acidophilus in adults traveling to different parts of the world found no benefit for the prevention of travelers' diarrhea when compared with placebo (101445). The effectiveness of this species may vary significantly based upon the destination of travel. Destinations in the same country can have different results, probably due to differences in bacteria and other microorganisms at different locations (10216).
• Ulcerative colitis. Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: The best evidence of benefit is for a specific combination product (Visbiome, ExeGi Pharma). Doses of 3 grams (equivalent to 900 billion colony-forming units (CFUs)) once or twice daily have been used in combination with conventional treatment. In children aged 1-16 years, doses of 450-1800 billion CFUs for up to one year have been used (3261,14370,14371,16841,95337). A meta-analysis of clinical research shows that taking this product as an adjunct to standard ulcerative colitis treatment can increase remission rates in adults and children by about 1.7-fold when compared with standard treatment alone (95337). Preliminary clinical research in patients with moderate to severe symptoms taking mesalazine 1200 mg daily shows that taking an unknown dose of L. acidophilus twice daily along with Bifidobacterium bifidum BGN4 and Ligilactobacillus salivarius (Acronelle, Bromatech srl, Milan, Italy) for 2 years modestly improves patient- and physician-scales of overall symptoms when compared with taking mesalazine alone. There were also improvements in stool frequency and rectal bleeding (110981). Although some contradictory evidence exists (3261,16841), most research shows that taking Visbiome or a combination of L. acidophilus LA-5 and Bifidobacterium animalis subsp. lactis BB-12 (Probio-Tec AB-25) does not prevent relapse in people who are already in remission (95337,95338).
• Urinary tract infections (UTIs). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In children aged 4 months to 5 years with a previous UTI, clinical research shows that taking a specific combination of L. acidophilus, Lacticaseibacillus rhamnosus, Bifidobacterium bifidum, and Bifidobacterium animalis subsp. lactis (Complete Probiotic Platinum) for 18 months increases the median time to the first incidence of recurrence by approximately 3 months and increases the percentage of children without a UTI during the study period from 83% to 97% (103436).
• Vaginal candidiasis. It is unclear if oral or intravaginal Lactobacillus acidophilus is beneficial for vaginal candidiasis. Details: In a small preliminary clinical trial in patients with recurrent vulvovaginal candidiasis who had undergone a week of oral fluconazole treatment followed by intravaginal L. acidophilus LA 02 and Limosilactobacillus fermentum LF10, 72.4% of patients demonstrated a lack of clinical recurrence over a 7 month observational period. All patients took fluconazole 200 mg three times in the first week followed by intravaginal application with at least 0.4 billion colony-forming units each of L. acidophilus LA 02 and Limosilactobacillus fermentum LF10, along with arabinogalactan and fructo-oligosaccharides (FOS) on alternate days for 10 days and then once weekly for 10 weeks (111781). However, a combination of L. acidophilus, Lacticaseibacillus rhamnosus, Lactobacillus delbrueckii, and Streptococcus thermophilus (Femilac) given intravaginally, does not seem to reduce the risk of vaginal candidiasis infection following use of antibiotics (12108). There is also some evidence that eating yogurt enriched with L. acidophilus daily does not reduce the risk of recurrent vaginal candidiasis (1245).
• Ventilator-associated pneumonia (VAP). Oral Lactobacillus acidophilus has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking L. acidophilus LA-5 1.75 billion colony-forming units (CFUs), Lactiplantibacillus plantarum 500 million CFUs, Bifidobacterium animalis subsp. lactis BB12 1.75 billion CFUs, and Saccharomyces boulardii 1.5 billion CFUs twice daily for 15 days reduces the risk of VAP to 12%, compared with 28% in those taking placebo. Half of the dose was given onto the oropharynx and half via a nasogastric tube (107524). More evidence is needed to rate Lactobacillus acidophilus for these uses.

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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.

(Read more about VITAMIN C)

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).

(Read more about CALCIUM)

LIKELY SAFE ...when used orally and appropriately. Lacticaseibacillus casei has been safely used alone or in combination with other ingredients in studies lasting up to 8 weeks (90230,112517).

CHILDREN: LIKELY SAFE
when used orally and appropriately in children of most ages. Lacticaseibacillus casei has been safely used alone in studies lasting up to 4 months (14373,107544). Also, a specific mixture (Latopic, Biomed S.A.) providing 1 billion CFUs of L. casei ŁOCK 0919 50%, Lacticaseibacillus rhamnosus ŁOCK 0900 25%, and L. rhamnosus ŁOCK 0908 25% has been used with apparent safety for 3 months in children under 2 years of age (107510). In addition, in children ages 4-17 years, a 1:1:1 combination of L. casei CECT 9104, Bifidobacterium animalis subsp. lactis CECT 8145, and Bifidobacterium longum CECT 7347 providing 1 billion CFUs has been used with apparent safety for 12 weeks (107531). There is insufficient reliable information available about the safety of L. casei in preterm infants with a birth weight under 1000 grams. Cases of bacteremia have occurred rarely in preterm infants given other probiotics (102416,111610,111612,111613,111850,111852,111853). The US Food and Drug Administration (FDA) has issued a warning about cases of serious infections caused by probiotics reported in very preterm or very low birth weight infants under 1000 grams (111610). Similarly, the American Academy of Pediatrics does not support the routine administration of probiotics to these infants due to conflicting data on safety and efficacy (111608).

PREGNANCY: POSSIBLY SAFE
when used orally and appropriately. A combination of Lacticaseibacillus casei, Lactobacillus acidophilus, and Bifidobacterium bifidum has been used with apparent safety for 6 weeks, starting at 24-28 weeks' gestation (95416,98430).

LACTATION:
There is insufficient reliable information available about the safety of Lacticaseibacillus casei during lactation. However, there are currently no reasons to expect safety concerns when used appropriately.

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LIKELY SAFE ...when used orally and appropriately. Lactobacillus acidophilus has been safely used as part of multi-ingredient probiotic products in studies lasting up to nine months (1731,6087,14370,14371,90231,90296,92255,103438,12775,107581)(110950,110970,110979,110998,111785,111793). ...when used intravaginally and appropriately. L. acidophilus has been used safely in studies lasting up to 12 weeks (12108,13176,13177,90265). There is insufficient reliable information available about the safety of non-viable, heat-killed L. acidophilus formulations when used orally.

CHILDREN: LIKELY SAFE
when used orally and appropriately in children of most ages. Lactobacillus acidophilus has been safely used for up to 5 days (96887). Also, combination probiotics containing L. acidophilus have been used with apparent safety in various doses and durations. L. acidophilus has been combined with Bifidobacterium animalis (HOWARU Protect, Danisco) for up to 6 months in children 3-5 years old (16847), with Bifidobacterium bifidum for 6 weeks (90602,96890), with Bifidobacterium bifidum and Bifidobacterium animalis subsp. lactis (Complete Probiotic Platinum) for 18 months in children 4 months to 5 years of age (103436), and in a specific product (Visbiome, ExeGi Pharma) containing a total of 8 species for 3 months in children 2-12 years old (107497). There is insufficient reliable information available about the safety of L. acidophilus in preterm infants with a birth weight under 1000 grams. Cases of bacteremia have occurred rarely in preterm infants given other probiotics (102416,111610,111612,111613,111850,111852,111853). The US Food and Drug Administration (FDA) has issued a warning about cases of serious infections caused by probiotics reported in very preterm or very low birth weight infants under 1000 grams (111610). Similarly, the American Academy of Pediatrics does not support the routine administration of probiotics to these infants due to conflicting data on safety and efficacy (111608).

PREGNANCY: POSSIBLY SAFE
when used orally and appropriately. A combination of Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum has been used with apparent safety for 6 weeks, starting at 24-28 weeks' gestation (95416,98430).

LACTATION:
There is insufficient reliable information available about the safety of Lactobacillus acidophilus during lactation. However, there are currently no reasons to expect safety concerns when used appropriately.

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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.

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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.

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ANTIBIOTIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking Lacticaseibacillus casei with antibiotic drugs might decrease the effectiveness of L. casei.  Details L. casei preparations usually contain live and active organisms. Therefore, simultaneously taking antibiotics might kill a significant number of the organisms (1740). Tell patients to separate administration of antibiotics and L. casei preparations by at least two hours.

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ANTIBIOTIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking Lactobacillus acidophilus with antibiotic drugs might decrease the effectiveness of L. acidophilus.  Details L. acidophilus preparations usually contain live and active organisms. Therefore, simultaneously taking antibiotics might kill a significant number of the organisms (1740). Tell patients to separate administration of antibiotics and L. acidophilus preparations by at least two hours.

(Read more about LACTOBACILLUS ACIDOPHILUS)

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.

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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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General ...Orally, Lacticaseibacillus casei is generally well tolerated.
Most Common Adverse Effects:
Orally: Mild gastrointestinal adverse effects.
Serious Adverse Effects (Rare):
Orally: There is concern that lactobacilli may cause infections in some people.

Gastrointestinal ...Orally, taking Lacticaseibacillus casei in combination with other probiotics may cause gastrointestinal side effects including abdominal pain (90291); however, these events are uncommon.

Immunologic ...Since Lacticaseibacillus casei preparations contain live and active microorganisms, there is some concern that they might cause pathogenic infection in some patients. Some lactobacilli species have been isolated in some cases of bacteremia, sepsis, splenic abscess, endocarditis, aortic dissection, necrotizing fasciitis, pancreatic necrosis, and meningoencephalitis. Most of these cases are thought to be due to the translocation of bacteria from other locations in the body in which they occur naturally, such as the oral cavity and gastrointestinal tract. The majority of cases are not related to the use of probiotic supplements and most are not associated with the use of L. casei (107543,112516). There is at least one case of L. casei bacteremia and endocarditis thought to be related with L. casei intake in a 71-year-old immunocompromised female (112520).
There are two cases of L. casei infection in a prosthetic joint (90282,112514). In one case, the 95-year-old female with a history of hypertension, diabetes, and heart disease was known to consume yogurt containing L. casei. However, it was not confirmed that the infection was related to the consumption of this product. Spread from the gastrointestinal tract or vaginal flora could not be ruled out (90282). In the case of an 80-year-old male, the cause was unknown as there was no probiotic supplementation and no underlying medical condition or infectious portal of entry (112514).
A specific probiotic preparation (NBL probiotic ATP, Nobel) containing L. casei, Lacticaseibacillus rhamnosus, Lactiplantibacillus plantarum, Bifidobacterium animalis subsp. lactis, fructo-oligosaccharides, galacto-oligosaccharides, colostrum, and lactoferrin was found to be a significant risk factor for vancomycin-resistant Enterococcus colonization in premature infants. Although there was no direct link to determine causation, it was hypothesized that the probiotic mixture helped to mediate the acquisition and transfer of antibiotic resistance genes (96890).

(Read more about LACTICASEIBACILLUS CASEI)

General ...Orally and intravaginally, Lactobacillus acidophilus is generally well tolerated.
Most Common Adverse Effects:
Orally: Mild gastrointestinal adverse effects.
Intravaginally: Vaginal discharge.
Serious Adverse Effects (Rare):
Orally: There is concern that L. acidophilus may cause infections in some people.

Dermatologic ...Orally, in one clinical trial, a combination of Lactobacillus acidophilus La-5, Lacticaseibacillus paracasei subsp. paracasei F19, and Bifidobacterium animalis subsp. lacltis BB-12 was associated with two cases of rash, one with itching. However, it is not clear if these adverse effects were due to L. acidophilus, other ingredients, the combination, or if the events were idiosyncratic (90236).

Gastrointestinal ...Orally, taking Lactobacillus acidophilus in combination with other probiotics may cause gastrointestinal side effects including epigastric discomfort (90239), abdominal pain (90239,90291,111785), dyspepsia (90239), flatulence (107497,107520), bloating (107497,111785), diarrhea (111785), vomiting (107537), and burping (90239); however, these events are uncommon.

Genitourinary ...Intravaginally, cream containing Lactobacillus acidophilus has been shown to cause increased vaginal discharge in about 5% of patients, compared to about 1% of patients receiving placebo cream (90237). Vaginal burning was reported by one person using intravaginal L. acidophilus and Limosilactobacillus fermentum in a clinical trial (111781).

Immunologic ...Since Lactobacillus acidophilus preparations contain live and active microorganisms, there is some concern that they might cause pathogenic infection in some patients. L. acidophilus has been isolated in some cases of bacteremia, sepsis, splenic abscess, liver abscess, endocarditis, necrotizing fasciitis, pancreatic necrosis, and meningoencephalitis. Most of these cases are thought to be due to the translocation of bacteria from other locations in the body in which they occur naturally, such as the oral cavity and gastrointestinal tract (107543,111782,111792). L. acidophilus endophthalmitis has been reported rarely (111787,111795). In one case, it was related to intravitreal injections for age-related macular degeneration in a 90-year-old female with an intraocular lens (111787). In another, it occurred following cataract surgery (111795).

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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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