Last verified: 17 days ago
Keratin
Also known as: hair keratin, KRT, cytokeratin, keratin protein, hydrolyzed keratin
Evidence under review. — Not yet rated
Structural protein found in hair, skin, and nails. Limited clinical evidence for supplement use.
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What it does
Keratin is a fibrous structural protein that makes up hair, nails, and the outer layer of skin. In the provided research, keratin appears primarily as a biological marker or measurement tool — for...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
No established dose
What the Science Says
Keratin is a fibrous structural protein that makes up hair, nails, and the outer layer of skin. In the provided research, keratin appears primarily as a biological marker or measurement tool — for example, keratin-18 levels are used to assess liver disease severity, and keratin gene expression is tracked in skin conditions like psoriasis and alopecia. No clinical trials in the provided data tested oral or topical keratin supplements for hair, nail, or skin improvement in healthy adults.
What It Doesn't Do
No evidence from these studies that taking keratin supplements grows thicker hair or stronger nails. Not shown to reverse hair loss on its own. No proof it improves skin elasticity or hydration as a supplement. The research here uses keratin as a disease biomarker, not a treatment.
Evidence-Based Benefits
Hair keratin gene expression increases with effective alopecia areata treatment and correlates with hair regrowth.
Weak EvidenceEffective at: No established dose
Supporting studies (click to view on PubMed):
Keratin-18 levels are used as a clinical marker to assess liver disease activity in NAFLD patients.
Weak EvidenceEffective at: No established dose
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Unknown — no absorption or bioavailability data provided in the supplied studies
Red Flags to Watch For
- None of the provided studies tested keratin as an oral supplement for hair, skin, or nail benefits
- Keratin in these papers is primarily a biological marker for disease, not a therapeutic ingredient
- 314 registered supplement products exist despite very limited clinical trial evidence for supplemental use
- Marketing claims about hair and nail growth are not supported by any of the provided research papers
Products Containing Keratin
See how Keratin is used in these analyzed products:
Augustinus Bader The Hair Revitalizing Complex
Supplement
Halo Beauty Hair Skin Nails Booster
Supplement
Hims Thick Fix System Total Hair Package
Supplement
Lifeable Biotin Gummies
Supplement
Collagen Nectar (Mango-Pineapple)
Supplement
Hormone Harmony PLUS+
Supplement
Frequently Asked Questions
What does Keratin do?
Structural protein found in hair, skin, and nails. Limited clinical evidence for supplement use.
What is the effective dose of Keratin?
No established dose
Is Keratin safe?
None of the provided studies tested keratin as an oral supplement for hair, skin, or nail benefits
What doesn't Keratin do?
No evidence from these studies that taking keratin supplements grows thicker hair or stronger nails.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25