Role of Biotin (Vitamin B7)
Biotin is a water-soluble B vitamin essential for keratin production—the structural protein of hair, skin, and nails. It acts as a coenzyme for carboxylases involved in fatty acid synthesis, gluconeogenesis, and amino acid metabolism.
Deficiency: Causes & Risk Factors
- Rare in healthy individuals (intestinal bacteria produce biotin; widely available in food).
- Risk factors: Prolonged raw egg white consumption (avidin binds biotin), total parenteral nutrition without biotin supplementation, certain anticonvulsants (valproate, carbamazepine), antibiotics disrupting gut flora, genetic biotinidase deficiency, pregnancy/lactation (increased demand), alcoholism, inflammatory bowel disease.
Signs of Deficiency
- Thinning hair, hair loss (alopecia)
- Brittle nails
- Scaly, red rash around eyes, nose, mouth (seborrheic dermatitis-like)
- Conjunctivitis
- Neurologic symptoms: depression, lethargy, hallucinations, paresthesias
Diagnosis & Treatment
- Clinical diagnosis; serum biotin levels are not routinely reliable.
- Therapeutic trial: Biotin 5–10 mg/day (pharmacologic dose) typically reverses hair/nail changes in weeks to months if deficiency is the cause.
- Dietary sources: Egg yolks, liver, nuts/seeds (almonds, sunflower), salmon, avocado, sweet potato, spinach.
Important Caveat
Most hair loss is not due to biotin deficiency. Androgenetic alopecia, telogen effluvium, thyroid disease, iron deficiency, and medications are far more common causes. Supplementing without deficiency rarely helps and can interfere with lab tests (thyroid, troponin, etc.). Test before megadosing.
