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.