About Keratin
Keratin is the primary structural protein of hair, skin, and nails. Supplemental keratin is typically solubilized (enzymatically hydrolyzed) to preserve bioactive disulfide bonds and improve absorption. Cynatine HNS is the most clinically studied form — two small RCTs (12–16 weeks, 500 mg/day) showed reduced hair shedding, improved nail hardness, and enhanced skin smoothness vs placebo. Mechanism involves supplying cysteine-rich peptides as direct building blocks for keratinized tissues. Standard hydrolyzed keratin powders lack the controlled reduction process and may have lower bioactivity. No established RDA or UL.
What Keratin supports
- Reduces hair shedding and supports hair strength
- Improves nail hardness and reduces breakage
- Supports skin smoothness and elasticity
How much Keratin to take
The RDA prevents deficiency. The effective range is what clinical trials used to actually move the outcome.
Effective
250–500
mg
Clinical trials with Cynatine HNS use 500 mg/day. Most supplements provide 250–500 mg/day of solubilized keratin.
Forms of Keratin compared
Cynatine HNS (solubilized)
Patented solubilized keratin; the only form with hair-growth RCT data (90 mg/day).
Solubilized keratin
Smaller molecules pass the gut intact — superior to standard hydrolysis.
Functional keratin
Mid-tier processed keratin; better absorbed than basic powder.
Bioavailable keratin
Marketing label without specific processing standard — verify the source.
Keratin peptides
Hydrolyzed peptide form; modest absorption, less studied than Cynatine HNS.
Hydrolyzed keratin
Standard hydrolysis may reduce bioactivity — partial absorption.
Keratin powder
Unprocessed keratin, poorly absorbed
Clinical evidence
Limited clinical evidence. Only 2 small clinical trials (12-16 weeks each) on hair, nail, and skin outcomes
NIH Fact Sheet