Vitamin B7 — Biotin

Biotin is a B vitamin most people have encountered in the context of hair, skin, and nail health — it’s a common ingredient in beauty supplements marketed around exactly those things. The connection isn’t entirely fabricated. Biotin does play a role in maintaining healthy hair and skin, and deficiency does produce noticeable changes in both. What the marketing tends to leave out is that biotin deficiency is genuinely rare, and supplementing it in someone who isn’t deficient produces no meaningful improvement in hair thickness, nail strength, or skin quality. The evidence for biotin supplements as a beauty intervention in healthy people is weak.

What biotin actually does at a functional level is support the metabolism of fats, carbohydrates, and protein — it’s a cofactor for enzymes involved in those processes. It also plays a role in gene regulation and is particularly important during pregnancy for normal fetal development.

Biotin is found in a wide range of foods, and the gut microbiome also produces some amount of it. Deficiency is most commonly seen in people who consume large amounts of raw egg whites over a long period — raw egg whites contain a protein called avidin that binds to biotin and prevents its absorption. Cooking the egg whites denatures avidin and eliminates the problem entirely.

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Reference Card

Vitamin type: Water-soluble Pillar: Nourish

What it does for you

• Supports metabolism of fats, carbohydrates, and protein
• Maintains healthy hair, skin, and nails
• Important for fetal development during pregnancy

Where to get it

• Eggs, beef liver, salmon, pork, sunflower seeds, sweet potato, almonds, spinach

Considerations

• Water-soluble — needs regular replenishment through food
• Deficiency is rare in people eating varied diets
• Raw egg whites block biotin absorption — cooking eliminates this entirely
• Biotin supplements are widely marketed for hair and nail growth but show no meaningful benefit in people who aren’t actually deficient

Signs your intake might be low

• Hair thinning or loss
• Skin rash, particularly around the face
• Brittle nails
• Fatigue

Common myths

• Biotin supplements will make your hair and nails grow faster — supplementing biotin in someone without a deficiency produces no meaningful cosmetic benefit; the supplement industry has significantly oversold this one
• You need to avoid eggs to prevent biotin deficiency — raw egg whites are the issue, not eggs themselves; cooked eggs are among the better dietary sources of biotin