Phytokeratin, a plant-based alternative to keratin, is often found in hair care products or those formulated for eyelashes and eyebrows. But what benefits does this active ingredient deliver to lashes and hair? Find out in this article.
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Hair, eyelashes, and eyebrows: benefits of phytokeratin?
Summary
- A closer look at the keratin found in hair, eyelashes, and eyebrows
- Phytokeratin, a plant-based active ingredient of interest for caring for hair, eyelashes, and eyebrows?
- Sources
Published July 26, 2022,
updated on August 13, 2025,
by
Sandrine, Scientific Editor
—
7 min read
≈ 95 %
Hair, eyelashes, and eyebrows are composed of keratin.
50 to 100 g
This refers to the weight that a single hair fiber can support.
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A closer look at the keratin found in hair, eyelashes, and eyebrows.
Keratin is a fibrous protein organized into hierarchical structures, forming microfibrils in the cortex of hair, eyelashes, eyebrows, and other body hair. This structured organization is responsible for the strength of the hair : in theory, if the scalp permitted, a head of about 120,000 hairs could support a weight of 12 tons. Keratin consists of chains of amino acids with a high proportion of cysteine, a sulfur-containing amino acid. The thiol groups (–SH) of cysteine can oxidize to form disulfide bonds (–S–S–), which function as bridges between keratin chains. These disulfide bridges are essential for the cohesion and stability of the hair fiber.
Keratin is also abundant in the cuticle, the outer layer of hair, eyelashes, and eyebrows. Composed of scale-like keratinized cells, the cuticle functions as a protective barrier. The alignment of these cells is essential: when it is disrupted, the fiber becomes more vulnerable. External aggressions such as UV radiation, heat, or chemical treatments can then degrade keratin, disturb cuticle cohesion, and promote dehydration, breakage, or even the shedding of body hair and hair.
Did you know? The disulfide bonds in keratin can be modified. This principle underlies hair-straightening and perming techniques. These methods break the disulfide bonds to reshape the hair, which is then fixed during reoxidation.
The importance of keratin for hair, eyelashes, and eyebrows.
Source: KWON I. K. & al. Human hair keratin and its-based biomaterials for biomedical applications. Tissue Engineering and Regenerative Medicine (2014).
Phytokeratin, a plant-based active ingredient of interest for caring for hair, eyelashes, and eyebrows?
Keratin is a cornerstone of hair and scalp integrity, so it’s not surprising that it’s so often used in cosmetics. However, this active ingredient is of animal origin (for example, it’s found in feathers, wool, or hooves), which can be a barrier for some people. To address this issue, phytokeratin has been developed. It is a natural alternative obtained through plant protein hydrolysis, such as wheat or almond, which has an amino acid structure similar to that of animal keratin. Through biomimicry, plant-based keratin could replicate the effects of animal keratin.
Nevertheless, it is important to note that the phytokeratin is a relatively new active ingredient in the cosmetics industry. To date, no clinical study has directly evaluated its effects on hair fibers or on the hairs of eyelashes and eyebrows. However, its biochemical similarity to animal keratin suggests that it could offer similar benefits and that it could, in particular, hydrate eyelashes, eyebrows, and hair. Indeed, phytokeratin contains several hydrophilic amino acids, including glutamine, serine, and threonine, which can bind to the surface of the hair fiber or follicle and form a protective film. Better protected, the fibers are less prone to breakage.
In addition to its moisturizing properties, phytokeratin may offer a more comprehensive protective action, particularly against environmental stressors such as UV rays. Although no study has yet evaluated this effect for phytokeratin, results obtained with a hydrolyzed form of animal keratin allow some hypotheses to be made. A recent study highlighted the photoprotective effects of hydrolyzed keratin on hair fibers. Researchers exposed hair strands to continuous irradiation simulating accelerated solar aging, after having pretreated them or not with a solution containing hydrolyzed keratin. Untreated hair showed a significant loss of mechanical strength (−14.32% tensile strength), whereas hair treated with hydrolyzed keratin was not only protected from this degradation but also saw its stiffness increase by 21.66% after exposure. Even though phytokeratin differs from animal keratin, it is also composed of short amino acid chains derived from a hydrolysis process; it could therefore have a comparable effect.
Phytokeratin may form a protective film on the surface of fibers that absorbs some UV radiation and, as it degrades, releases peptide fragments that penetrate the fiber to reinforce its internal structure.
Photoprotection of hair by hydrolyzed keratin.
Source: CHANG K. & al. Performance and mechanism of hydrolyzed keratin for hair photoaging prevention. Molecules (2025).
The question of the effectiveness of keratin, whether of animal or plant origin, largely depends on its ability to interact with the hair fiber. A recent study on curly hair, previously straightened with a sodium hydroxide–based solution, evaluated the influence of hydrolyzed keratin peptides of different molecular weights on the hair’s physical properties. Three fractions were tested: low molecular weight keratin (≈ 221 Da), medium molecular weight keratin (≈ 2,577 Da), high molecular weight keratin (≈ 75,440 Da), along with a reference amino acid, L-leucine (131 Da).
The results show that low- and medium-molecular-weight peptides are able to penetrate into the hair cortex, whereas high-molecular-weight peptides primarily bind to the surface, with penetration limited to the outer layers. This internal penetration was confirmed by cross-sectional fiber analysis: at ambient humidity, hair treated with 1% low-molecular-weight peptides or 1% leucine showed a significant increase in diameter compared to control hair (respectively +11.7% and +11.0% relative to the straightened control). This increase in cross-sectional diameter reflects interaction with internal protein structures and serves as a strong indicator of cortex penetration.
Mechanically, medium- and high–molecular-weight peptides significantly increased Young’s modulus and reduced fiber breakage under both low (20%) and high (80%) humidity. At 20% humidity, breaking strength increased by approximately 18.6% for medium–molecular-weight peptides and by 16.3% for high–molecular-weight peptides compared to the relaxed control.
Breaking stress measured at 20% and 80% relative humidity as a function of treatment and hair condition.
Source: HINDLEY M. & al. 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 (2020).
These data suggest that molecular weight influences not only penetration depth but also the mode of action. Low molecular weight keratin peptides could penetrate the hair fiber and act from within to reinforce it, potentially by reestablishing hydrogen bonds broken by external stress. High molecular weight keratin peptides would primarily act on the surface, filling in cuticle irregularities and limiting damage. Since phytokeratin has a molecular structure similar to that of keratin, by analogy, one can assume the similar mechanisms of action.
Sources
KWON I. K. & al. Human hair keratin and its-based biomaterials for biomedical applications. Tissue Engineering and Regenerative Medicine (2014).
MEYERS M. A. & al. Structure and mechanical behavior of human hair. Materials Science and Engineering (2017).
HINDLEY M. & al. 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 (2020).
HWANG Y.-S. & al. Keratin-mediated hair growth and its underlying biological mechanism. Communications Biology (2022).
CHANG K. & al. Performance and mechanism of hydrolyzed keratin for hair photoaging prevention. Molecules (2025).
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