Supplement · Vitamins
Vitamin B7 (biotin)
Also known as: Biotin, Vitamin H
Heavily marketed for hair and nails, but only helps if you are genuinely deficient.
- Evidence
- Unproven· human data
- Sources cited
- 1
- Last reviewed
- 22 July 2026
Biotin is a B-vitamin involved in metabolism, marketed hard for hair, skin and nails. Real deficiency (uncommon) can cause hair and skin problems, and correcting it helps — which is the seed of truth behind the marketing.
In people who are not deficient, though, evidence that biotin improves hair or nail growth is weak. It also has a practical hazard: high-dose biotin can skew several blood tests (including thyroid and troponin), so mention it to your doctor before testing.