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Biotin (vitamin B7)

EFSA claims for hair, skin and energy metabolism, the 'hair, skin and nails' marketing claim is weak relative to deficiency-state evidence.

Why

Biotin (vitamin B7) is a cofactor for several carboxylase enzymes in fatty acid and glucose metabolism. EFSA-authorised health claims cover normal energy-yielding metabolism, normal psychological function, normal hair, skin, mucous membranes, and nervous system function. The popular 'high-dose biotin for hair growth' marketing claim is supported only in cases of biotin deficiency; in non-deficient adults, evidence is weak.

How it works

Cofactor for pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase and methylcrotonyl-CoA carboxylase. Required for normal protein and lipid synthesis.

Expected onset · Cosmetic effects (if any beyond deficiency correction) over 3–6 months

How to take

Dosage

RDI: 30–35 µg/day. Marketed 'hair growth' supplements: 2,500–10,000 µg/day (well above any documented physiological need in non-deficient adults).

Timing

With food

On the label

Stated micrograms (not milligrams). 'Hair, skin and nails' marketed doses are far above any documented physiological need.

Ideal for

People with diagnosed biotin deficiency (rare) or biotinidase deficiency (paediatric, clinical context); included in B-complex nutrient adequacy contexts.

Safety

Very wide safety margin. **High-dose biotin interferes with biotinylated immunoassay measurements, including TSH, free T4, free T3, troponin (and many others)**. Can cause falsely-elevated or falsely-low results. Discontinue at least 72 hours before relevant blood tests. Pregnancy: standard B-complex doses are safe.

Evidence

At a glance

EFSA-authorised claims cover six functions. Patel 2017 review: no published RCT supports biotin for hair growth in non-biotin-deficient adults. FDA 2019 Safety Communication flagged immunoassay interference, clinically important caveat for high-dose users.

Where to get it

Shop Biotin (vitamin B7) on Amazon

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