SupplementsHair, skin & nailsPromising, not proven
There is an obvious objection to swallowing keratin for your hair: hair is keratin, and you do not absorb hair — you digest protein into amino acids. It is a fair point, and it is why cheap “keratin” powders are probably pointless. The more interesting version is solubilised, bioactive keratin (branded Cynatine HNS), engineered to stay intact enough to deliver keratin peptides and their cysteine-rich sulphur to the follicle — and it has actually been trialled.
Key takeaways
- Ordinary keratin is inert and hard to absorb; Cynatine HNS is a solubilised, disulphide-rich keratin standardised for bioavailability.
- A randomised, placebo-controlled trial (about 50 women, 90 days) reported less hair loss, more shine and stronger nails versus placebo.1
- It rests on essentially one industry-funded trial — genuinely promising, not established.
- Mechanistically it is a premium, cysteine-rich protein delivery — overlapping with the L-cysteine rationale.
The idea — and the obvious objection
Digestion breaks proteins into amino acids and short peptides, so the sceptic’s line — “you cannot eat hair to grow hair” — is basically right for raw keratin. The manufacturers’ answer is a proprietary solubilisation process that yields keratin fragments said to survive digestion in a bioavailable, still-disulphide-linked form, plus the cysteine load that keratin synthesis needs. Whether that mechanism is as special as claimed, or is just a good way to deliver sulphur amino acids, is the open question.
The Cynatine trial
The headline study by Beer and colleagues (2014) randomised around 50 women to Cynatine HNS or placebo for 90 days and reported improvements in hair strength and loss, brightness, and nail health in the keratin group.1 The endpoints are reasonable and the result is positive — but it is a single trial funded by the ingredient’s maker, which is exactly the kind of evidence that warrants interest and independent replication before firm claims.
How to read it
One honest way to see oral keratin: a sophisticated, more expensive route to the same place L-cystine aims for — supplying the sulphur-rich building blocks of keratin. If that framing is right, its ceiling is similar to the other keratin-substrate supplements: helpful at the margins for people who are shedding, not a fix for genetic hair loss.
If you want to try it
It is safe and well tolerated, so a 90-day trial is low-risk if the cost suits you — look specifically for the Cynatine HNS form (the one that was studied) rather than generic “keratin”, and judge it against the shedding, not against a marketing photo.
References
Adult research summary for education, not a prescription. These are food supplements, not treatments for disease.
- Beer C, Wood S, Veghte RH. A clinical trial to investigate the effect of Cynatine HNS on hair and nail parameters. ScientificWorldJournal 2014;2014:641723. pubmed.ncbi.nlm.nih.gov
This article summarises nutrition science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.