Biotin (Vitamin B7)

    Written by:
    Daryl Nault, Katie Jantz

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    by:

    Nick Milazzo, Giulia Guerrini
    Last Updated: September 4, 2025

    Biotin is one of the essential B vitamins used by the body primarily as an enzymatic cofactor. While it is popular as a beauty supplement for hair, skin, and nails and very preliminary evidence suggests it may have a role in these uses, its role is not well-supported. Potential interactions with diabetes are also not well understood.

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    Overview

    Dosage information

    The only known supplemental dose of biotin that has been tested orally in humans — for the purposes of enhancing the quality of brittle nails — is 2.5mg taken once daily over six months.

    This dose appears relatively safe, although it is much higher than the recommended daily intake (RDI) of biotin which ranges from 25-30mcg (youth) upwards to 100mcg (adults). The biotin dose found in many multivitamins (30mcg or 0.03mg) seems more than sufficient.

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