PROTEIN
Hydrolysed Keratin
A protein derived from keratin and broken down into smaller peptides, used in haircare to help hair look and feel smoother, stronger-looking and more resilient through heat styling.
Source
Keratin protein, broken down into smaller peptides
Used for
Hair conditioning, smoother-feeling hair
How it works
Keratin is the structural protein that makes up hair's outer cuticle and inner cortex. Hydrolysed Keratin is keratin that has been broken down into smaller peptides and amino acids, which lets it deposit onto the hair's surface and partly penetrate into the hair shaft, rather than just sitting on top of it.
A laboratory study on human hair fibres found that Hydrolysed Keratin forms a smoothing, protective film on the hair cuticle and partly penetrates into the cortex, helping hair keep a sleek surface and its strength after UV exposure.
Hydrolysed Keratin suits regular use as part of a haircare routine, and works well alongside other conditioning and smoothing ingredients rather than needing to be used alone.
A laboratory study on human hair fibres found that Hydrolysed Keratin forms a smoothing, protective film on the hair cuticle and partly penetrates into the cortex, helping hair keep a sleek surface and its strength after UV exposure.
Hydrolysed Keratin suits regular use as part of a haircare routine, and works well alongside other conditioning and smoothing ingredients rather than needing to be used alone.
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01
Small keratin peptides that coat and partly penetrate the hair shaft
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02
Forms a smoothing, protective film on the hair's cuticle
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03
Helps hair keep its strength and sleek surface after sun exposure
Questions
What is hydrolysed keratin?
Keratins are the key structural proteins inside hair. Hydrolysed keratin is keratin that has been broken down into smaller pieces, peptides and amino acids, so that it can attach to or enter the hair fibre. (Malinauskyte et al., 2021; Fan et al., 2025)
Does hydrolysed keratin get inside the hair?
Partly, and it depends on the size of the pieces. In laboratory testing on hair fibres, small and mid-sized keratin peptides travelled deep into the hair's inner cortex, while the largest stayed mainly on the surface. The mid-sized and large peptides also helped reduce breakage. (Malinauskyte et al., 2021)
Can hydrolysed keratin help hair exposed to the sun?
It can help hair hold on to its strength. In laboratory testing, hydrolysed keratin formed a film on the hair's cuticle and partly penetrated the cortex, and hair conditioned with it kept a sleek surface and its strength after UV exposure, while untreated hair lost some of its strength. (Fan et al., 2025)
Where it comes from
The key structural proteins of the hair's inner cortex are keratins, which form fine filaments, and keratin-associated proteins, which form the matrix around them. (Malinauskyte et al., 2021; Fan et al., 2025)
To make it, keratin is partially broken down (hydrolysed) into peptides and amino acids. The size of these pieces varies widely between ingredients, from very small fragments to large peptides, and size matters: smaller pieces enter the hair more readily, while larger ones tend to stay on the surface. (European Commission CosIng; Malinauskyte et al., 2021)
To make it, keratin is partially broken down (hydrolysed) into peptides and amino acids. The size of these pieces varies widely between ingredients, from very small fragments to large peptides, and size matters: smaller pieces enter the hair more readily, while larger ones tend to stay on the surface. (European Commission CosIng; Malinauskyte et al., 2021)
Good to know
Hydrolysed keratin suits regular use as part of your haircare routine and works well alongside other conditioning and smoothing ingredients. As with any new product, patch test first if your scalp is easily irritated.
The research
- Fan J, Wu L, Wang J, Bian X, Chen C, Chang K. Performance and Mechanism of Hydrolyzed Keratin for Hair Photoaging Prevention. Molecules. 2025;30(5):1182. PMID: 40076404. DOI: 10.3390/molecules30051182. (opens in a new tab)
- Malinauskyte E, Shrestha R, Cornwell PA, Gourion-Arsiquaud S, Hindley M. Penetration of different molecular weight hydrolysed keratins into hair fibres and their effects on the physical properties of textured hair. International Journal of Cosmetic Science, 2021;43(1):26-37. PMID: 32946595 (opens in a new tab)
- European Commission CosIng database: Hydrolyzed Keratin (functions: antistatic, film forming, hair conditioning, humectant, skin conditioning) (opens in a new tab)
Found In
New
NewType: Hair Care
Hydrokeratin Plumping Conditioner
390mlRegular price £34.00Sale price Regular price
