howtosupplement
Deficiency/Beauty

Biotin

Water-soluble B vitamin that corrects biotin deficiency and may help brittle nails, mainly in adults with low intake or higher needs.

Biotin

Biotin

47
score
C
evidence
Caution
risk
Use with caution

This supplement may interact with medications, medical conditions or sensitive populations. Review safety before use.

Quick Take

Worth considering only for confirmed low biotin or brittle nails — most healthy adults won't notice much.

Biotin is a water-soluble B vitamin found in egg yolks, liver, salmon, nuts, and seeds. It acts as a cofactor for carboxylase enzymes involved in fat, glucose, and amino-acid metabolism. Its clearest use is correcting biotin deficiency; smaller human studies suggest it may help brittle nails and deficiency-related hair or skin changes. People with low intake, pregnancy-related low status, frequent raw egg white intake, or certain medications tend to benefit most.

Proven Benefits

01
Corrects biotin deficiency
02
May improve brittle nails
03
May correct low biotin in pregnancy
04
May reduce hair loss if deficient
05
May improve deficiency-related rash

Protocol

Amount
30-300 mcg
Frequency
Once daily
When
Any time of day — consistency matters more than timing; can be taken with or without food.

Onset Time

1-4 weeks for deficiency symptoms; 3-6 months for nail changes

Who Should Consider

Adults with confirmed or suspected low biotin intake
People with brittle, splitting nails
Pregnant adults with marginal biotin status
Long-term anticonvulsant users
People regularly consuming raw egg whites

Food Sources

  • Beef liver (~30 mcg per 85 g)
  • Egg yolk (~10 mcg per egg)
  • Salmon (~5 mcg per 85 g)
  • Roasted sunflower seeds (~2.6 mcg per 28 g)
  • Sweet potato (~2.4 mcg per medium)
  • Almonds (~1.5 mcg per 28 g)

How It Works

Biotin is the active cofactor for several carboxylase enzymes, including pyruvate, acetyl-CoA, and propionyl-CoA carboxylases. These enzymes help convert food into usable energy and support fatty-acid synthesis, keratin structure, and normal skin and nail turnover. When biotin is low, rapidly growing tissues like hair, skin, and nails are often affected first.

Updated 5/19/2026