Biotin (vitamin B7) is a water-soluble vitamin widely known for supporting the health of hair, skin, and nails. However, scientific evidence regarding the true efficacy of supplementation is limited. This guide addresses the dermatological evidence for biotin and its correct use.
What Is Biotin?
Biotin is an essential vitamin that serves as a cofactor for carboxylase enzymes and plays a role in fatty acid synthesis, amino acid metabolism, and gluconeogenesis. It is thought to have an indirect role in keratin production. The recommended daily intake for adults is 30–100 mcg.
Efficacy in Hair Loss
Evidence regarding biotin's effect on hair loss is mixed. Improvement in hair loss has been observed following supplementation in individuals with biotin deficiency. However, biotin deficiency is quite rare in the general population, and there is no strong evidence that additional supplementation increases hair growth in people with normal biotin levels.
A systematic review published in the Journal of Drugs in Dermatology noted that biotin supplementation is beneficial only in cases of deficiency.
Symptoms of Biotin Deficiency
Biotin deficiency is uncommon, but the risk increases in the following situations:
- Prolonged consumption of raw egg whites (avidin binds biotin)
- Long-term antibiotic use
- Pregnancy and breastfeeding
- Biotinidase enzyme deficiency (genetic)
- Long-term total parenteral nutrition
Deficiency symptoms include hair loss, dry and scaly skin rash, brittle nails, conjunctivitis, and neurological symptoms.
Effect on Nail Health
The evidence for biotin's effect on brittle nails is stronger than for hair loss. Daily supplementation of 2.5 mg of biotin has been reported to increase nail thickness by up to 25%. However, improvement may require a long period of 6–12 months to become apparent.
Dosage and Side Effects
Biotin doses used for dermatological purposes are generally in the range of 2.5–5 mg/day. Because it is water-soluble, any excess is excreted in urine and the risk of toxicity is low. However, high-dose biotin can cause false results in laboratory tests such as thyroid function tests and troponin measurements. It is important to report biotin supplementation before a blood test.
This article is for informational purposes only. Please consult a qualified physician for treatment decisions.