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Research · Supplements

Keratin hydrolysate

Three small randomized trials of two keratin products report better skin moisture, elasticity and wrinkle measures, less hair loss and stronger nails than placebo after 90 days. Two were funded by the product's seller. One product also contained vitamins and minerals. The abstracts give no effect sizes or adverse event counts.

Add to Bio HackChecked 2026-11-12
Status
Dietary supplement in the US. Not approved by the FDA as a drug for any use.
Also called
soluble keratin, solubilized keratin, hydrolyzed keratin, keratin peptides, Cynatine HNS, Cynatine, feather keratin hydrolysate, FKH, Kera-Diet, KeraGLO, functional keratin
Taken for
hair loss, hair growth, hair strength, nails, brittle nails, nail strength, skin aging, wrinkles, skin elasticity, skin hydration

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help3

Reported risks0

No risks sourced yet.

What people take it for, and what was found

Shown to help3

LimitedStudied in women

Skin aging: wrinkles, elasticity and moisture

Small trials funded by sellers found better skin moisture, elasticity and wrinkles over 90 days in women.

The numbers and sources
Effect
In 50 women, Cynatine HNS (500 mg of Cynatine keratin plus vitamins and minerals a day) for 90 days improved skin moisture, elasticity, wrinkles, compactness and appearance against a maltodextrin placebo [1]. In adult women with signs of skin aging, 500 or 1,000 mg a day of feather keratin hydrolysate for 90 days improved skin roughness, wrinkle features, deep skin moisture, elongation and elasticity, thickness and gloss against placebo [2].
Population
50 women, 25 per group [1]; adult women in three groups [2].
Sources
[1], [2]
Caveats
The abstracts report statistical significance without effect sizes [1][2]. Cynatine HNS combines keratin with vitamins and minerals, so keratin's share of the effect is unknown [1]. The feather keratin trial was fully funded by BCF Life Sciences, which sells the product as Kera-Diet, and three authors work in its research department [2]. The product is mainly free amino acids (83.5% or more), not intact keratin [2].
Limited

Hair loss and hair strength

Limited evidence: small trials reported less hair loss, and a review of mixed products found more growing hairs with no change in total hair count.

The numbers and sources
Effect
In 50 women, Cynatine HNS for 90 days improved hair loss, growth, strength, amino acid composition and luster against placebo [3]. Hair gloss improved against placebo with feather keratin hydrolysate [2]. A meta-analysis of 14 studies of eight commercial supplements, Cynatine HNS among them, found lower telogen hair density (MD -5.91, 95% CI -6.74 to -5.08) and higher anagen density (MD 10.48, 95% CI 8.81 to 12.14) against placebo, and no significant change in total hair count (P 0.06) [4].
Population
50 women, 25 per group [3]; adult women [2]; 967 adults with alopecia or hair thinning [4].
Sources
[3], [2], [4]
Caveats
Roxlor Global funded the Cynatine trial and supplied its materials, and one author was Roxlor's general manager [3]. The meta-analysis pooled different products, so it does not isolate keratin, and its authors call for more independent research [4].
LimitedStudied in women

Nail strength

Small trials found better nail strength and hardness over 90 days in women, each trial linked to its seller.

The numbers and sources
Effect
Cynatine HNS improved nail strength and appearance against placebo over 90 days [3]. Feather keratin hydrolysate improved nail hardness and gloss against placebo over 90 days [2].
Population
50 women [3]; adult women [2].
Sources
[3], [2]
Caveats
Two small trials of different products, each linked to its seller [2][3]. The abstracts give no effect sizes.

Doses studied

The Cynatine HNS trials gave two capsules a day providing 500 mg of keratin plus vitamins and minerals for 90 days [1][3]. The feather keratin hydrolysate trial gave 500 or 1,000 mg a day for 90 days [2].

Risks

Checked, no increase found1

LimitedStudied in women

Adverse events in trials

Limited evidence: one 90-day trial reported the product well tolerated. Other trials did not report adverse events.

The numbers and sources
Effect
The feather keratin trial reports the product was well tolerated. Of nine dropouts, four left for personal reasons and the rest had intestinal problems the authors attributed to seasonal flu [2]. The Cynatine abstracts do not report adverse events [1][3].
Population
Adult women in a 90-day trial [2].
Sources
[2], [1], [3]
Caveats
Small, short trials with limited safety reporting.

Claims tested and not found

  1. That feather keratin hydrolysate changes dermal fiber density or alignment. Fiber anisotropy and density improved from day 0 but only tended to improve against placebo [2].

Sources

  1. Beer C, Wood S, Veghte RH. A randomized, double-blind, placebo-controlled clinical trial to investigate the effect of Cynatine® HNS on skin characteristics. International Journal of Cosmetic Science. 2013. https://doi.org/10.1111/ics.12084
  2. Tursi F, Nobile V, Cestone E, et al. The Effects of an Oral Supplementation of a Natural Keratin Hydrolysate on Skin Aging: A Randomized, Double-Blind, Placebo-Controlled Clinical Study in Healthy Women. Journal of Cosmetic Dermatology. 2025. https://doi.org/10.1111/jocd.16626
  3. Beer C, Wood S, Veghte RH. A clinical trial to investigate the effect of Cynatine HNS on hair and nail parameters. The Scientific World Journal. 2014. https://doi.org/10.1155/2014/641723
  4. Alanazi R, Alshammari S, Aldossari K, et al. Evaluating the Effectiveness of Commercial Oral Supplements for Hair Growth: A Systematic Review and Meta-Analysis. Journal of Cosmetic Dermatology. 2026. https://doi.org/10.1111/jocd.70817

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