Keratin
Also known as: keratin hydrolysate, feather keratin hydrolysate, FKH, hydrolyzed keratin
Effective Dosage
500–1000 mg daily based on one clinical study
What the Science Says
Keratin is the structural protein that makes up your hair, nails, and the outer layer of skin. One randomized, double-blind, placebo-controlled study found that taking 500 mg or 1000 mg of a feather-derived keratin hydrolysate daily for 90 days was associated with improvements in skin moisture, elasticity, wrinkle appearance, and nail hardness in adult women. The supplement is essentially a mix of free amino acids derived from breaking down keratin protein, and researchers suggest these amino acids may act as building blocks or signaling molecules rather than being incorporated directly as keratin.
What It Doesn't Do
Not proven to regrow hair lost to alopecia or other conditions. No evidence it works for men or younger adults. One small study is not enough to call it proven. The amino acids in keratin supplements are not unique — you get similar amino acids from food protein. Don't expect dramatic results; improvements in the one trial were modest. No evidence it strengthens nails faster than a balanced diet.
Evidence-Based Benefits
Keratin is a structural protein that plays a crucial role in the health of hair, skin, and nails. Evidence from multiple systematic reviews and clinical trials suggests that keratin supplementation can improve hair strength and reduce hair loss.
Strong EvidenceEffective at: No established dose
Source: auto-research
Absorption & Bioavailability
Unknown — the one clinical trial used a hydrolyzed form (free amino acids), which is likely better absorbed than intact keratin protein, but no pharmacokinetic data was provided in the available studies.
Red Flags to Watch For
- Only one small clinical trial (in women only) supports cosmetic benefits — evidence base is very thin
- Most keratin research in the provided papers is about keratin as a biomarker, industrial material, or structural protein — not as a supplement
- Feather-derived keratin raises quality and sourcing questions; look for third-party testing
- Products with 314 registered formulations but only one supporting RCT suggests heavy marketing outpaces the science
- No long-term safety data available from the provided studies
Products Containing Keratin
See how Keratin is used in these analyzed products:
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: 2026-04-06