💊 What it does
Biotin (vitamin B7) is a water-soluble B vitamin essential as a cofactor for five carboxylase enzymes involved in gluconeogenesis (glucose production from non-carbohydrate sources), fatty acid synthesis, and amino acid catabolism. It also plays a role in gene expression. It is widely supplemented for hair, skin, and nail health — a market driven largely by beauty claims — though the evidence specifically for this application in people without deficiency is limited. True biotin deficiency (causing hair loss, skin rash, and neurological symptoms) is rare.
👤 Who needs it
People with biotinidase deficiency (a rare genetic condition). Those consuming large amounts of raw egg whites regularly — avidin in raw egg white binds biotin and blocks absorption. Pregnant women have slightly increased requirements. People taking anticonvulsant medications long-term. For hair and nail concerns when deficiency is suspected.
🥦 Food sources first
Good dietary sources: nutritional yeast (one of the richest sources), almonds, sweet potato, eggs, sunflower seeds, broccoli, sweet corn, avocado. Gut bacteria also produce biotin — people with healthy microbiomes have some endogenous biotin production.
🗓 When to supplement
When biotin deficiency is suspected or confirmed. For hair loss or nail brittleness specifically related to biotin deficiency. Not evidenced for hair growth in people with normal biotin status.
🏷 Best form to look for
Standard biotin (D-biotin) in capsule form. Sublingual biotin may have slightly better absorption.
⏰ When to take it
Can be taken at any time. Avoid taking alongside raw egg whites.