Keratin

Protein

What is it

Keratin is a structural protein that makes up hair, nails, and the outer layer of skin in mammals. Supplemental keratin is typically extracted from wool (e.g., Cynatine) and sold for hair, skin, and joint support.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Hair strength and appearance

Limited Evidence

Small RCTs of Cynatine HNS report improvements in hair strength, gloss, and reduction in shedding. Most studies are industry-supported.

Nail strength

Limited Evidence

Similar small trials report nail improvements; replication beyond industry sponsorship is limited.

How it works

Solubilized keratin contains cysteine-rich amino acid sequences that may provide substrates for hair and nail protein synthesis, as well as functional peptides that could affect skin and joint matrix. Trials of branded keratin products (Cynatine HNS, Cynatine FLX) report improvements in hair strength, gloss, and nail integrity over 12-24 weeks, though most studies have been industry-funded.

Dosage

No RDA. Trials of solubilized keratin (Cynatine HNS) typically use 500 mg/day; joint trials use similar doses.

When and how to take it

No timing baseline established. Daily consistent intake required; results take 8-24 weeks to develop.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Solubilized keratin (Cynatine HNS)

Best-studied form.

Hydrolyzed for absorption.

Hydrolyzed keratin powder

Less studied than branded forms.

Generic hydrolysate.

Safety

Well tolerated in published trials. Possible allergic reactions to wool-derived products in sensitive individuals.

Who should be cautious

People with wool allergies should avoid wool-derived keratin. Vegetarians/vegans should note the animal source.

Interactions

No significant clinical interactions reported.

Frequently asked questions

Does oral keratin really improve hair?⌄

Some small trials suggest modest benefit for hair strength and appearance, but most are industry-funded. Effects are usually subtle.

Is supplement keratin vegan?⌄

No. Most supplemental keratin is derived from wool or animal hair.

References

Keratin on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Keratin (PubMed search) — PubMed link

Track Keratin with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.