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evidence · mechanism · dose
Supplements/Vitamin

Vitamin B7 (Biotin)

aka Vitamin H

Carboxylase cofactor marketed for hair, skin, and nail support.

Skin, Hair & Nails

Overview

Carboxylase cofactor marketed for hair, skin, and nail support.

Natural sources
  • Egg yolk
  • Liver
  • Nuts
Common forms
  • D-biotin

Mechanism of action

Prosthetic group for 5 mammalian carboxylases involved in fatty acid synthesis and gluconeogenesis.

Pathways
  • · Carboxylation reactions

Effects on the body

Supports
Keratin infrastructure (if deficient)

Organ system effects

Skin

Deficiency causes alopecia and dermatitis.

Evidence-based benefits

Reverses brittle nails in some cases

Limited evidence

Helps biotin-deficient hair loss only

Limited evidence

Potential side effects

Common
    Rare
      Serious
      • · Falsely abnormal thyroid/troponin labs at high doses

      Drug interactions

      Lab assays (thyroid, troponin)
      Stop ≥48h before testing.
      moderate

      Supplement interactions

      Pairs well with

      None listed.

      Avoid combining with

      No specific avoidances listed.

      Dosing & bioavailability

      Typical dose
      30 mcg general; 2,500–5,000 mcg for hair/nails

      Where to buy

      Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

      Vitamin
      Vitamin B7 (…
      Amazon
      Wide selection · fast shipping
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      iHerb
      Global delivery · curated brands
      Vitamin
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      Thorne
      Practitioner-grade · NSF tested

      Scientific evidence (9)

      Systematic reviewExamine.com Supplement Database · 2023

      Vitamin B7 (Biotin): pharmacology, clinical evidence, and safety — narrative review

      Examine.com Research Team

      Curated narrative review of human and preclinical evidence for Vitamin B7 (Biotin), including mechanism, typical dosing, and safety considerations.

      Key findings

      Best-supported outcome: Reverses brittle nails in some cases (evidence: limited). Additional outcomes and limitations summarized in the full profile.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — Reverses brittle nails in some cases

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) Reverses brittle nails in some cases" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "Reverses brittle nails in some cases". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — Helps biotin-deficient hair loss only

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) Helps biotin-deficient hair loss only" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "Helps biotin-deficient hair loss only". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — randomized controlled trial

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — meta-analysis

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — pharmacokinetics

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — safety adverse events

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewPubMed (NLM) · 1970

      PubMed: Vitamin B7 (Biotin) — dose response

      Live PubMed search

      Live results for "Vitamin B7 (Biotin) dose response" across the PubMed/MEDLINE peer-reviewed index.

      Key findings

      Opens current human and preclinical literature matching Vitamin B7 (Biotin) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

      Open study
      Systematic reviewGoogle Scholar · 1970

      Google Scholar: Vitamin B7 (Biotin) — clinical evidence

      Live Scholar search

      Cross-database citation index for Vitamin B7 (Biotin) as it relates to "clinical evidence".

      Key findings

      Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

      Open study
      Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.