Biotin

Biotin (vitamin B7) is a water-soluble B vitamin involved in metabolic processes and in the formation of keratin, the structural protein of hair, skin, and nails. Adequate biotin supports normal hair growth in people with a confirmed deficiency, but true biotin deficiency is uncommon in otherwise healthy individuals with a balanced diet.

Dietary sources of biotin include eggs, nuts, seeds, legumes, and some vegetables, and the vitamin is also produced in small amounts by gut bacteria; supplements are widely marketed for hair health, though strong clinical evidence that they improve hair growth in people without deficiency is limited. If you are considering biotin supplements, consult a healthcare professional first because high doses can interfere with certain laboratory tests and may not be appropriate for everyone.