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Biotin (Vitamin B7)
Cofactor for fatty acid synthesis and gluconeogenesis — strongest evidence for brittle nail syndrome and keratin infrastructure support.
What the evidence says
Biotin helped in about half (5/8) of the studies that measured an effect — promising, but not unanimous.
Most evidence is from high-quality meta-analyses and randomised trials published 1989–2026 with a typical study size of 82 participants.
Based on 21 studies · 5 meta-analyses · 12 RCTs · 9,683 total participants
Confidence
HighWhat the studies found
By outcome
See full supplement plans that include Biotin.
Biotin has an evidence score of 8.5/10 — very strong evidence based on 21 indexed studies, including 9 meta-analyses. Cofactor for fatty acid synthesis and gluconeogenesis — strongest evidence for brittle nail syndrome and keratin infrastructure support.
The commonly studied dose of Biotin is 2500-5000mcg (2.5-5mg) for hair/nails. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Biotin is in the morning. Taking it with food is preferred. Biotin (vitamin B7) is a water-soluble B vitamin involved in carboxylase enzyme function for energy metabolism, gluconeogenesis, and keratin production.
Vitamin E
Likely helpsLipid-soluble antioxidant that shields cell membranes from oxidative damage — natural mixed tocopherols preferred over synthetic forms.
Methylfolate
Likely helpsBioactive folate that bypasses MTHFR conversion — critical for the 30-40% of people with gene variants affecting mood and methylation.
Last reviewed May 2026 · evidence from 40 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Biotin (Vitamin B7) is a water-soluble B vitamin essential for fatty acid synthesis, gluconeogenesis, and amino acid metabolism. While true deficiency is rare, supplementation is popular for hair, skin, and nail health. Evidence is strongest for brittle nail syndrome; hair benefits are less proven but widely reported anecdotally.
Supports protein building blocks of hair and nails
Essential for energy metabolism
How Biotin works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
2500-5000mcg (2.5-5mg) for hair/nails
Can be taken without food
| Form | Type |
|---|---|
| 💊Biotin capsules or tablets | Recommended |
| 🍬Gummies | Alternative |
| 💊Combined hair/skin/nail formulas | Alternative |
Standalone biotin is most economical. Higher doses (5000-10000mcg) are common for cosmetic purposes.
Minimum: 12 weeks
Optimal: 24 weeks
Cycling: Not required
Note: Water-soluble, can be taken any time. Consistent daily use is key.
You can get biotin from these foods and drinks. Doses are typical per-serving estimates — actual content varies by brand, brew, cooking, etc.
40 mcg per 2 pieces
2 large egg yolks. Pasture-raised hens produce 3–4× more vitamin D. Whole eggs (white + yolk) add ~12 g protein.
Dose-response data unavailable. The current published research for Biotin does not provide sufficient dose-specific outcome data to generate reliable dose-response curves.
Refer to the Dosage & Timing section above for recommended dose ranges based on available evidence.
Improved nail thickness and reduced brittleness
May improve hair thickness and reduce shedding
Safe at normal doses; may help prevent deficiency
HIGH BIOTIN INTERFERES WITH LAB TESTS — stop 48-72 hours before bloodwork
May reduce biotin levels
Biotin deficiency despite supplementation
Tip: Reduce dose
Biotin is generally safe at recommended doses, with a few precautions worth noting. The most commonly reported side effects are acne (rare). Use caution if any of these apply to you: Known allergy or hypersensitivity to Biotin or related compounds; May interfere with lab test results (thyroid panels, troponin, hormone assays) — inform healthcare providers before blood tests.
Thiamine
Probably helpsConverts carbohydrates into cellular energy and supports acetylcholine synthesis for healthy nerve and brain function.
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