Biotin: Does Nothing for Your Hair, and It Skews Your Blood Tests

Summary

Biotin is sold as the "hair, skin and nails vitamin," and for the overwhelming majority of people that pitch is empty — there is no adequate trial showing it regrows hair in anyone who is not deficient, and genuine biotin deficiency is rare in the developed world — yet the supplement is not a harmless nothing: the high doses in beauty products (5–20 mg, up to roughly 650× the ~30 mcg you actually need) interfere with common blood-test immunoassays, an FDA-warned cause of falsely low troponin (a reported death, missed heart attacks) and a thyroid pattern indistinguishable from Graves' disease,