Biotin (Vitamin B7)
The classic 'hair, skin & nails' supplement. Honestly: it only helps in genuine deficiency — which is rare. In well-nourished people the evidence is missing, and high doses distort lab tests.
How it works
Biotin is a water-soluble B vitamin and coenzyme for carboxylase enzymes central to fat, sugar and amino-acid metabolism. True deficiency is rare but shows up as skin, hair and nerve problems. High-dose hair and skin benefits in non-deficient people are poorly supported, and high doses can skew lab tests (e.g. thyroid, troponin).
Dosage
Dietary needs are practically always met. High-dose 'beauty' products (5,000–10,000 µg) are rarely necessary.
Considerations
An honest take: biotin improves hair and nails only if there's a genuine deficiency (e.g. certain conditions) — in well-nourished people there's no good evidence of an effect. Important warning: high-dose biotin distorts numerous lab tests (including thyroid and troponin), which can lead to dangerous misdiagnoses — stop before blood draws and disclose use.
