Vitamin B7 (biotin)

Unproven· human data

Also known as: Biotin, Vitamin H

Heavily marketed for hair and nails, but only helps if you are genuinely deficient.

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.

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Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.

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