Maximum Nails by Supplement Spot

LIKELY EFFECTIVE

• Biotin deficiency. Oral and injectable biotin prevents and treats biotin deficiency. Details: Biotin up to 10 mg daily has been used to treat and prevent biotin deficiency. Injections of biotin 150 mcg daily for 3-5 days have been used in adults. Biotin deficiency might occur due to different etiologies such as inherited biotinidase deficiency, malnutrition, chronic use of anticonvulsants, pregnancy, and excessive and chronic raw egg consumption (6243,19347). A very small study in newborns aged 1-6 months shows that adding biotin to infant formula safely improves biotin status in formula-fed infants (111365). The validity of these findings is limited by a lack of blinding, no randomization, and the small sample size.

POSSIBLY INEFFECTIVE

• Multiple sclerosis (MS). In spite of contrary reports, high-dose biotin (300 mg daily) does not reduce disability in patients with progressive MS. It also does not seem to be linked to an increased risk for relapse. Details: Although most earlier research suggested benefit, the highest quality evidence shows that high-dose biotin does not improve outcomes in progressive MS (95662,102963,102966,104011). A large multi-centered randomized clinical trial (SPI2) in patients with progressive MS and high disability shows that taking biotin 100 mg three times daily for 15 months does not improve disability, as measured on the expanded disability status scale (EDSS), or 25-foot walking time, when compared with placebo. The SPI2 clinical trial also did not find that biotin increases the rate of relapse (104011), a concern raised in one observational study of high-dose biotin (104000). Also, a large observational study of adults with progressive MS failed to identity an increase in annualized relapse rates in patients that reported taking biotin when compared with controls (105716). Other observational research has also found no effect on the relapse risk (102963,102964). There is some speculation that any increased rate of relapse identified in some high-dose biotin cohorts might be due to detection bias or reduced compliance with disease-modifying therapies.
• Seborrheic dermatitis. Oral biotin doesn't seem to improve seborrheic dermatitis of infancy. Details: A clinical trial in infants with seborrheic dermatitis shows that biotin given by mouth does not improve symptoms when compared with placebo (8469).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alopecia areata. It is unclear if oral biotin is beneficial for alopecia areata. Details: A small clinical study in healthy adults with alopecia areata shows that weekly injections of intramuscular biotin 5 mg/1 mL and dexpanthenol 250 mg/2 mL for 6 weeks reduces hair fall count and transiently increases hair density compared with baseline (111366). The validity of these findings is limited by a lack of a placebo control group, small sample size, and short duration of treatment. It is unclear if the effects are due to biotin, dexpanthenol, or the combination. Another small clinical study in 9-year-old children with alopecia areata shows that taking biotin 20 mg with zinc aspartate 100 mg orally along with topical application of clobetasol propionate 0.025% daily for one year promotes hair regrowth in 33% of children, compared with 0% in the group receiving the steroid deflazacort (6932). It is unclear if these effects are due to biotin, zinc, topical clobetasol, or the combination.
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Although there is interest in using oral biotin for ALS, there is insufficient reliable information about the clinical effects of biotin for this condition.
• Biotin-thiamine-responsive basal ganglia disease. Adding oral biotin to oral thiamine does not seem to improve most symptoms associated with this condition, although it may slightly speed recovery from acute crisis in children. Details: A small case series in children ages 1-12 years with biotin-thiamine-responsive basal ganglia disease has found that adding biotin 5 mg/kg daily to thiamine 40 mg/kg daily for 30 months is not associated with additional symptomatic improvement in encephalopathy, seizures, dystonia, or other neurologic sequelae when compared with taking only thiamine. However, taking biotin with thiamine is associated with a 1-day reduction in recovery from acute crisis when compared with thiamine alone (95661).
• Brittle nails. Low quality clinical studies suggest that oral biotin might improve nail thickness and prevent the splitting of brittle nails. Details: Some small, low quality clinical studies in people with brittle nails shows that taking biotin 2.5 mg orally daily for 1.5 to 15 months increases nail thickness and decreases the splitting of fingernails and toenails in some people when compared with baseline (171,35593). The validity of these findings is limited by the small study sizes and the lack of a comparator group.
• Depression. Although there is interest in using oral biotin for mild depression, there is insufficient reliable information about the clinical effects of biotin for this condition.
• Diabetes. It is unclear if oral biotin is beneficial for type 2 diabetes. Details: A meta-analysis of randomized controlled trials shows that taking biotin 1.5-15 mg orally daily for 1-3 months does not improve fasting blood glucose or serum insulin levels when compared with placebo. However, the validity of these results is limited by inclusion of subjects with and without diabetes (110044). A very small study in adults with type 2 diabetes also shows that taking biotin 5 mg three times daily for 28 days does not affect glucose or insulin levels when compared to baseline (11579). Biotin has also been studied in combination with other ingredients. Preliminary clinical research shows that a taking a specific supplement containing a combination of biotin 2 mg and chromium picolinate 600 mcg (Diachrome, Nutrition 21) can lower blood glucose and glycated hemoglobin levels in patients with type 2 diabetes who are poorly controlled on oral hypoglycemic drugs (12385,12390,15169). It is unclear if these effects are due to biotin, chromium, or the combination.
• Diabetic neuropathy. Although there is interest in using oral and intramuscular biotin for diabetic neuropathy, there is insufficient reliable information about the clinical effects of biotin for this condition.
• Muscle cramps. It is unclear if biotin is beneficial for improving muscle cramps in patients undergoing hemodialysis. Details: Patients undergoing hemodialysis are prone to muscle cramps. A small clinical study in patients with hemodialysis-related muscle cramps shows that taking biotin 1 mg in the morning daily for at least one week prevents and reduces severity of muscle cramps when compared to baseline. Cessation of biotin led to recurrence of cramps, and restarting oral biotin led to resolution of cramps during hemodialysis (89475). The validity of these findings is limited by the lack of comparator group. More evidence is needed to rate biotin for these uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Cancer. Although there is interest in using oral L-cysteine for prevention of cancers of the upper gastrointestinal tract, there is insufficient reliable information about the clinical effects of L-cysteine for this purpose.
• Diabetes. Although there is interest in using oral L-cysteine for diabetes, there is insufficient reliable information about the clinical effects of L-cysteine for this condition.
• Erythropoietic protoporphyria (EPP). Although there is interest in using oral L-cysteine for EPP, there is insufficient reliable information about the clinical effects of L-cysteine for this condition.
• Hangover. Oral L-cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that an immediate release product (Catapult Cat L-cysteine vitamin tablet) providing L-cysteine 1200 mg in combination with other ingredients, taken six times between 7 pm and midnight in conjunction with alcohol 1.5 grams/kg over 3 hours, modestly reduces symptoms of hangover, including nausea, headache, stress, and anxiety, when compared with placebo. Each L-cysteine tablet also contained thiamine 50 mg, riboflavin 1.4 mg, niacin 16 mg, vitamin B6 1.4 mg, biotin 50 mcg, folic acid 200 mcg, vitamin B12 2.5 mcg, and vitamin C 80 mg (109709). Other researchers have questioned the validity of the statistical methods used in this study and suggest that not all of the noted outcomes were statistically significant (109716).
• Photoreactive keratectomy. It is unclear if oral L-cysteine is beneficial for promoting wound healing after photoreactive keratectomy. Details: Preliminary clinical research shows that taking L-cysteine 100 mg twice daily for 14 days starting one week before photoreactive keratectomy reduces complete corneal healing time by about 2 days when compared with taking placebo (109727).
• Venous leg ulcers. Topical L-cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that topical application of a cream containing L-cysteine 2 mg/gram, glycine 10 mg/gram, and D,L-threonine 1 mg/gram for 12 weeks modestly increases healing and decreases pain when compared with placebo. However, there was no difference in exudate, offensive smell, or granulation. The cream was used as part of a treatment regimen involving cleaning and bandaging, two to five days each week (10255).
• Smoking cessation. It is unclear if oral L-cysteine is beneficial for promoting smoking cessation. Details: Preliminary clinical research shows that use of a slow-release lozenge containing L-cysteine 3 mg (Acetiumlozenge; Biohit Oyj) with each cigarette for 6 months does not increase the odds of smoking cessation when compared with placebo (109714). However, this study may have been inadequately powered to detect a difference between groups. An adequately powered study by the same research group shows that using this lozenge increases the odds of smoking cessation by about 51% when compared with placebo (109710).
• Stroke. Although there is interest in using oral L-cysteine for stroke prevention, there is insufficient reliable information about the clinical effects of L-cysteine for this purpose. More evidence is needed to rate L-cysteine for these uses.

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POSSIBLY EFFECTIVE

• Osteoporosis. Higher dietary intakes of silicon in males and premenopausal females seem to be associated with higher bone mineral density (BMD), but it is unclear whether silicon supplements reduce the risk of osteoporosis. Details: Males and premenopausal females who have dietary intakes of silicon of at least 40 mg daily seem to have higher BMD than those with lower intakes. This could reduce the risk of osteoporosis (10470,12425). However, it is unclear if silicon supplements can reduce the risk for osteoporosis. Silicon intake has also been evaluated in postmenopausal females. Clinical and population-based research suggests that higher silicon intake does not seem to benefit postmenopausal females in general, although it may benefit those on hormone replacement therapy (10470,12425,75118,92135). Bone loss in postmenopausal females is primarily due to bone resorption. Silicon seems to affect only bone formation (12425).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. It is unclear if oral silicon is beneficial in patients with aging skin. Details: A small preliminary clinical study in healthy volunteers aged 40-60 years shows that taking a specific product (Exsynutriment by Biotec) containing organic silicon 600 mg in hydrolyzed marine collagen once daily, 15 minutes before breakfast, for 90 days improves skin firmness, hydration, and texture, but not wrinkles, brightness, or softness, when compared with placebo (100837).
• Alzheimer disease. Although there has been interest in using oral silicon for Alzheimer disease, there is insufficient reliable information about the clinical effects of silicon for this condition.
• Androgenic alopecia. Although there has been interest in using oral silicon for androgenic alopecia, there is insufficient reliable information about the clinical effects of silicon for this condition.
• Cardiovascular disease (CVD). Although there has been interest in using oral silicon for CVD, there is insufficient reliable information about the clinical effects of silicon for this condition.
• Dental peri-implantitis. It is unclear if oral silicon is beneficial in patients with peri-implantitis. Details: A small, preliminary clinical study in patients aged 18-75 with peri-implantitis shows that a specific choline-stabilized orthosilicic acid product (BioSil, Bio Minerals NV) containing silicon 5 mg and choline 100 mg, taken twice daily for 12 months, does not improve markers of inflammation and periodontal disease (i.e. probing pocket depth, bleeding on probing) when compared with placebo (110028). However, this study may not have been adequately powered to detect a difference between groups. More evidence is needed to rate silicon for these uses.

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LIKELY SAFE ...when used orally and appropriately. Biotin has been safely used in doses up to 300 mg daily for up to 6 months. A tolerable upper intake level (UL) has not been established (1900,6243,95662,102965). ...when applied topically as cosmetic products at concentrations of 0.0001% to 0.6% biotin (19344).

POSSIBLY SAFE ...when used intramuscularly and appropriately (8468,111366).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Biotin has been safely used at adequate intake doses of 5-25 mcg daily for up to 6 months (173,6243,19347,19348,111365). A tolerable upper intake level (UL) has not been established.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately. Biotin has been safely used at the adequate intake (AI) dose of 30 mcg daily during pregnancy and 35 mcg daily during lactation. It has also been used in supplemental doses of up to 300 mcg daily (6243,7878). A tolerable upper intake level (UL) has not been established.

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LIKELY SAFE ...when used orally in amounts found in foods. There is insufficient reliable information available about the safety of L-cysteine when used orally in amounts greater than those found in foods or when used topically.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts found in foods. There is insufficient reliable information available about the safety of amounts greater than those found in foods; avoid use. Some research suggests that taking L-cysteine during lactation increases levels of free L-cysteine in breastmilk. However, these levels are lower than those found in some commercial hydrolyzed protein infant formulas (109718).

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LIKELY SAFE ...when used orally and appropriately in amounts commonly found in foods (7135,10470,92135). It is estimated that the average dietary intake of silicon is 20-50 mg daily (110029); however, there is currently no established recommended dietary allowance or tolerable upper intake level for silicon (7135,92136,95009,110029).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods (7135,10470). It is estimated that the average dietary intake of silicon is 20-50 mg daily (110029). There is insufficient reliable information available about the safety of silicon when used in larger, medicinal amounts; avoid using.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.  Details Animal research suggests that L-cysteine can have hypoglycemic effects (109722).

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General ...Orally and topically, biotin is generally well tolerated.
Most Common Adverse Effects: None.

Gastrointestinal ...Orally, high-dose biotin has been rarely associated with mild diarrhea. Transient mild diarrhea was reported by 2 patients taking biotin 300 mg daily (95662).

Pulmonary/Respiratory ...In one case report in France, a 76-year-old female frequent traveler developed eosinophilic pleuropericarditis after taking biotin 10 mg and pantothenic acid 300 mg daily for 2 months. She had also been taking trimetazidine for 6 years (3914). Whether eosinophilia in this case was related to biotin, pantothenic acid, other substances, or patient-specific conditions is unknown. There have been no other similar reports.

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General ...Orally, L-cysteine is well tolerated in amounts found in foods. When used in higher doses or when applied topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

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General ...Orally, silicon in the amounts found in food and water is not associated with adverse effects.
Serious Adverse Effects (Rare):
Inhaled: Crystalline silicon dioxide in the form of quartz dust found in industrial and occupational settings is associated with an increased risk of diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD), lung cancer, glomerulonephritis, vasculitis, and rheumatoid arthritis.

Cardiovascular ...Case control studies have shown that occupational exposure to silicon dioxide-containing compounds may cause vasculitis (75114). Patients with occupational pulmonary silicosis may develop microscopic polyangiitis (inflammation of the blood vessels in the nose, sinuses, throat, lungs, and kidneys, also known as Wegener's granulomatosis).

Dermatologic ...Occupational silica exposure may be a risk factor for scleroderma, particularly in males (75099).

Genitourinary ...Limited reports in humans indicate that long-term use of large amounts of antacids containing magnesium trisilicate may be associated with urolithiasis and silicon-containing stones (11760,11861,75075,75103). However, fewer than 30 cases associated with antacids containing silicates have been reported, despite these products being commercially available since the 1930s. Although exceptionally rare, silicon dioxide kidney stones can also occur without magnesium trisilicate ingestion (11556). Their formation is caused by an acidic urinary pH. In at least one case, urine alkalinization resulted in resolution of the symptoms (75075).
Case-control studies have shown that occupational exposure to silicon dioxide is related to antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (75114). High silicon levels in patients undergoing chronic hemodialysis have been associated with nephropathy (75089).

Hepatic ...High silicon levels in patients undergoing chronic hemodialysis have been associated with liver disease (75089).

Musculoskeletal ...High silicon levels in patients undergoing chronic hemodialysis have been associated with bone disease (75089). A meta-analysis suggests that the risk of rheumatoid arthritis is elevated with occupational exposure to silicon dioxide (75078).

Neurologic/CNS ...High silicon levels in patients undergoing chronic hemodialysis have been associated with neuropathy (75089).

Pulmonary/Respiratory ...Occupational exposure to crystalline silicon dioxide dust is associated with an increased risk of pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD), and lung cancer (75076,75081,75084,75114). Patients with occupational pulmonary silicosis may develop microscopic polyangiitis (inflammation of the blood vessels in the nose, sinuses, throat, lungs, and kidneys, also known as Wegener's granulomatosis). Meta-analyses suggest that occupational exposure to silicon dioxide increases the risk of lung cancer (75085,75095,75115). An analysis of 19 studies shows that lung cancer risk is approximately 2 times higher for those with silicosis (75115). It is not clear whether silicon dioxide is carcinogenic in the absence of silicosis (75083).

(Read more about SILICON)