Biotin (Vitamin B7)

We evaluated 123 human studies on Biotin (Vitamin B7), including 12 randomised controlled trials and 6 meta-analyses or systematic reviews; the controlled studies include 1,170 participants in total. As of 11 October 2026.

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1. What Is Biotin (Vitamin B7)? Occurrence, Origin and Forms

Biotin is a water-soluble vitamin of the B group. In the body it acts as a coenzyme of several carboxylases involved in fat, carbohydrate and protein metabolism. As a supplement it is traditionally associated with hair, skin and nails, and medically it is given in confirmed biotin deficiency and in inborn disorders of biotin metabolism.

Biotin occurs in many foods, among them egg yolk, liver, nuts, oats, soy and yeast, and is additionally produced by gut bacteria. In body cells it is present bound to protein.

In foods biotin is bound to protein and is released in the gut by the enzyme biotinidase. In supplements it is present in free form; human studies examine free biotin taken by mouth, high-dose biotin and biotin as a component of combination products, and in metabolic medicine also biotin as an infusion.

Forms and Preparations Studied

• Biotin from foods, bound to protein
• Free biotin as a dietary supplement (tablets, capsules, drops)
• High-dose biotin as used in studies of neurological disease
• Biotin in combination products with other vitamins and minerals
• Biotin for injection or infusion in inborn metabolic disorders

Not covered on this page:

• Other B vitamins such as thiamine, riboflavin, pantothenic acid, folate and cobalamin are substances in their own right, even when they occur in the same products.
• Combination products for hair, skin and nails that contain zinc, selenium or amino acids alongside biotin are not studies of biotin alone.
• Interference of laboratory tests by biotin, for instance in immunoassays, is an analytical safety topic and not an area of application.

2. What Does Biotin (Vitamin B7) Do? Results by Area

How to read the table: counted are human studies whose results concern the area. “High” means at least one meta-analysis and two controlled studies showing improvement, or at least three controlled studies of which three quarters show improvement, with at least 300 participants in total. “Moderate” means at least two controlled studies showing improvement, as a majority, or one meta-analysis alongside controlled studies. “Low” means one controlled study showing improvement. Where an area has no controlled study, the strength of evidence is at most “low” (result “reviews only” or “observational data only”). Everything else is “unclear”. A study counts as showing improvement when at least half of its outcomes in this area improved. Reviews of combination products do not count as meta-analyses; results that only describe side effects or shares of users do not count as an effect. The same study is counted only once.

3. What the Studies Show in Detail

Biotin (Vitamin B7) and Biotin Deficiency: Human Studies

In pregnant women with increased excretion of 3-hydroxyisovaleric acid, a sign of mild biotin deficiency, this decreased with biotin in a randomized trial, while it increased slightly with placebo 15. In children with severe protein-energy malnutrition, the activity of biotin-dependent enzymes in lymphocytes increased with biotin, most strongly in those with initially low levels 20. The evidence is considered moderate, as both studies are small and involve different populations and outcome measures.

Further studies in this area: 30 35 41 45 49 50 52 61 62 65 77 79 83 84 86 91 99 103 107

Biotin (Vitamin B7) and Multiple Sclerosis: Human Studies

In multiple sclerosis, high-dose biotin (MD1003) has been tested against placebo in several randomized trials 7925. In a randomized trial in progressive MS, disability improved in some patients on high-dose biotin, and in none on placebo 7. EDSS progression was also lower 7. The follow-up study SPI2 did not confirm this benefit 25. Another randomized controlled trial showed no difference in visual acuity, retinal nerve fiber layer thickness, and quality of life in MS-related chronic vision loss 9. A systematic review with meta-analysis found no confirmed difference from placebo in disability and EDSS, but more often a faster walking time 1. The certainty of evidence is low: the first study showed benefit in some patients, but the follow-up study and the meta-analysis did not confirm this for disability. It remains open whether a subgroup benefits, for example in walking ability.

Further studies in this area: 38 46 80 81 94 95 99 100 104 110 111 112 114 115 116 117

Biotin (Vitamin B7) and Hair Loss: Human Studies

A systematic review found three studies on biotin in hair loss; the most informative, placebo-controlled one showed no difference in hair growth 4. With biotin from a plant extract, with or without silica, hair loss decreased in a placebo-controlled study compared with baseline 8. A hair product for application with Redensyl, saw palmetto and biotin performed better together with platelet-rich plasma than Procapil with platelet-rich plasma 12. Injections with biotin and dexpanthenol from two manufacturers reduced hair loss in both groups; there was no group without biotin 13. In acne patients taking isotretinoin, the proportion of growing hairs increased with additional biotin compared with baseline 18. It remains open whether biotin helps in hair loss mainly in a biotin deficiency.

Further studies in this area: 87 96 102 109

Biotin (Vitamin B7), Skin and Skin Inflammation: Human Studies

In acne patients taking isotretinoin, skin moisture decreased significantly without biotin, but not with additional biotin; a direct group comparison was not reported 18. With biotin from a plant extract, with or without silica, skin elasticity increased from baseline in a placebo-controlled study 8. Both studies are small, one was not randomized, and neither reports a direct comparison with the control group. It remains open whether the effects also occur in individuals with adequate biotin status without concomitant medications.

Biotin (Vitamin B7), Glucose and Lipid Metabolism: Human Studies

In adults with type 2 diabetes, total cholesterol fell with biotin in a meta-analysis; the reduction in fasting blood glucose and triglycerides was not statistically confirmed, insulin remained unchanged 2. For mixtures of biotin and chromium picolinate, two randomized controlled studies reported improvements in blood glucose and lipid values in type 2 diabetes, but these findings apply to the mixture and not to biotin alone 614. In the meta-analysis, only the reduction in total cholesterol is confirmed; whether biotin alone lowers blood glucose must be clarified by larger studies.

Biotin (Vitamin B7) and Brittle Nails: Human Studies

With biotin from a plant extract, with or without silica, nail roughness decreased from baseline in a placebo-controlled study with 105 participants 8. A review names biotin alongside collagen peptides, keratin, MSM, and orthosilicic acid among substances that may improve the appearance, strength, and brittleness of nails 105. The certainty of evidence is unclear because only one controlled study is available, which does not report a comparison with placebo, and it remains open whether the participants had a biotin deficiency.

Biotin (Vitamin B7): Further Outcomes in Studies

In children with asthma, biotin in addition to standard therapy reduced the inflammatory markers TNF-α and 8-OHdG more than placebo; lung function improved only with L-carnitine 11. The other works in this area are predominantly observational studies or investigate biotin in combination products; controlled studies on clinical endpoints are still pending here.

Further studies in this area: 40 42 47 48 51 52 53 54 55 56 57 58 59 60 63 64 66 67 68 69 70 71 72 73 74 75 76 77 78 82 85 86 88 89 90 91 92 93 99 100 101 106 107 113 118

4. How Is Biotin (Vitamin B7) Dosed? Preparation, Dose and Duration in Studies

The studies mostly used oral biotin: as a dietary supplement, high-dose as a drug (MD1003) in multiple sclerosis or in combination products with other vitamins, minerals or plant extracts. Biotin was injected together with dexpanthenol in hair loss 13, applied in a hair product with Redensyl and saw palmetto 12. The doses and dosage forms are listed in the table.

5. Is Biotin (Vitamin B7) Safe? Side Effects in Studies

Adverse events with high-dose biotin in multiple sclerosis occurred no more frequently than with placebo 179; in children with asthma, biotin proved to be safe 11. However, high-dose biotin distorted laboratory tests in some of those treated, and in no one with placebo 1.

6. What Remains Open: Limits of the Evidence

• Most controlled studies are small and short; large long-term studies are still pending.
• Whether the findings for hair, skin and nails are tied to a biotin deficiency is an open question.
• Many findings come from combination products and apply to the mixture, not to biotin alone.
• In multiple sclerosis, the results are inconsistent and only some of the endpoints were investigated.
• For most uses, controlled studies with clinical endpoints are still pending.

7. Bottom Line: What Is Established About Biotin (Vitamin B7)

Biotin is a water-soluble B vitamin that, as a coenzyme of several carboxylases, is involved in fat, carbohydrate and protein metabolism. In type 2 diabetes, biotin lowered total cholesterol in a meta-analysis; the effect on blood glucose is not yet confirmed. For hair, skin and nails, measured values improved in small studies mainly compared with baseline; the most informative placebo-controlled hair study found no difference. Many positive results come from combination products and therefore do not apply to biotin alone. In progressive multiple sclerosis, high-dose biotin showed benefit in an initial study, and the follow-up study did not confirm it. In signs of biotin deficiency, such as in pregnancy, biotin improved biotin-dependent metabolic values. Biotin was well tolerated; in high doses it can distort laboratory tests.