Biotin (Vitamin B7)
- Effective dose
- 30–2500 mcg
- Evidence
- 2/5· Emerging
Last updated June 1, 2026
What it is
Biotin (vitamin B7) is a water-soluble B vitamin that acts as a cofactor for enzymes involved in metabolizing fats, glucose, and amino acids. True deficiency is rare, and most people meet needs through diet.
Benefits
Biotin only reliably improves hair and nail health in people who are actually deficient; trials in brittle nails used about 2.5 mg/day, but evidence for benefit in well-nourished people is weak.
When to take it
Taken daily at any time, with or without food; the adequate intake for adults is 30 mcg.
Side effects
No known toxicity and no upper limit, even at high doses. The main hazard is laboratory interference: intakes of roughly 10 mg/day or more can skew thyroid, vitamin D, and troponin assays, with one documented patient death from a falsely low troponin result — tell clinicians about biotin use before blood tests.
Sources
Products containing Biotin (Vitamin B7)
No products in our database contain this ingredient yet.