Benefits
Hair improvements (single industry-funded RCT)
An RCT in 50 females over 90 days showed Cynatine HNS produced statistically significant improvements vs placebo in hair pull test (less hair loss), hair strength, hair growth, hair luster, and amino acid composition of hair. Notable limitations: industry-sponsored (the Cynatine manufacturer); single small trial; not independently replicated; combination product (keratin + vitamins/minerals).
Nail strength improvement
The same trial showed Cynatine HNS significantly improved nail strength and appearance vs placebo over 90 days. Nail benefits may overlap with general protein/biotin effects rather than keratin-specific effects per se — though authors propose direct keratin amino acid bioavailability for hair/nail keratin synthesis.
Possible osteoarthritis benefit (separate Cynatine FLX product)
An RCT investigated Cynatine FLX on osteoarthritis symptoms. A different formulation from Cynatine HNS but using similar solubilized keratin technology, it showed some benefit on OA symptoms over placebo. Modest evidence; mechanism speculatively involves cysteine bioavailability for joint tissue support.
Cysteine and sulfur amino acid delivery
Keratin is unusually rich in cysteine — a sulfur-containing amino acid important for hair/nail structure (disulfide bonds), glutathione synthesis (antioxidant), and connective tissue. Solubilized keratin may serve as a bioavailable cysteine source distinct from N-acetylcysteine (NAC). Mechanism more plausible than 'keratin → keratin' direct deposition (which doesn't happen — proteins are digested to amino acids first).
Mechanism of action
Cysteine delivery for sulfur amino acid pool
Keratin's distinguishing feature is high cysteine content (~10-17% of amino acids in hair keratin, vs ~1-2% in typical dietary proteins). Disulfide bonds between cysteine residues give keratin structures rigidity. After ingestion and digestion, keratin-derived cysteine enters general amino acid pool — useful for synthesizing new keratin in hair/nail follicles, glutathione production, and other sulfur-amino-acid-dependent processes.
Bioavailability via solubilization (the Cynatine technology)
Native keratin is highly resistant to digestion due to extensive disulfide cross-linking. Cynatine technology uses proprietary processing (likely involving disulfide bond reduction) to produce soluble keratin peptides that are bioavailable. Standard intact wool keratin would be poorly absorbed; solubilized keratin overcomes this barrier.
Antioxidant via increased glutathione synthesis
Cysteine availability is rate-limiting for glutathione synthesis (GSH = γ-glutamyl-cysteinyl-glycine). Increased dietary cysteine from solubilized keratin may support GSH synthesis and overall antioxidant capacity — relevant for hair follicle oxidative stress protection.
Synergistic vitamin/mineral cofactors (Cynatine HNS combination)
The Cynatine HNS product combines keratin with biotin (essential cofactor for keratin synthesis), zinc (cofactor for many keratin-related enzymes), copper, and B vitamins. Effects observed in clinical trials reflect the combination rather than keratin alone — making attribution to specific component challenging.
Clinical trials
Randomized double-blind placebo-controlled trial (Beer C, Wood S, Veghte RH 2014, ScientificWorldJournal 2014:641723, doi:10.1155/2014/641723). EudraCT 2014-002645-22.
50 females randomized to Cynatine HNS active group (n=25, 2 capsules/day delivering 500 mg Cynatine keratin + vitamins/minerals) or placebo (n=25, maltodextrin 370 mg) for 90 days. Endpoints: hair loss, hair growth, hair strength, amino acid composition, hair luster, nail strength and appearance.
Cynatine HNS group showed statistically significant improvements vs placebo in: hair pull test (reduced hair loss), hair strength, hair growth, hair luster, and nail strength/appearance. One withdrawal in Cynatine group after Day 30. Concluded: 'Cynatine HNS is an effective supplement for improving hair and nails in 90 days or less.' major limitations: industry-funded (Roxlor Global); single trial without independent replication; combination product confounds keratin attribution.
Randomized double-blind placebo-controlled clinical trial (Beer C, Wood S, Veghte RH 2013, J Diet Suppl 10(3):184-194, doi:10.3109/19390211.2013.822449).
Subjects with osteoarthritis symptoms randomized to Cynatine FLX or placebo. Cynatine FLX is a different formulation from Cynatine HNS but shares the solubilized keratin technology.
Cynatine FLX showed benefits on OA symptoms over placebo. Different product/dose/formulation from the hair/nail trial. Demonstrates that solubilized keratin technology has been studied across multiple indications, though each trial is limited and industry-sponsored.
Evidence-based review (Katta R, Skin Therapy Lett 24(5):7-13).
Comprehensive review of supplements marketed for skin, hair, and nail health including biotin, collagen peptides, solubilized keratin, MSM, choline-stabilized orthosilicic acid, and others.
Reviewed Cynatine HNS evidence as part of broader assessment. Concluded that biotin, collagen peptides, solubilized keratin, MSM, and choline-stabilized orthosilicic acid have shown clinical improvements in nail appearance, strength, and brittleness in published trials. Notes evidence is generally derived from small industry-sponsored studies and replication remains limited. Author recommendation: reasonable to consider as adjunct interventions but not first-line therapy.