Evidence supporting the use of: Hydrolyzed keratin
For the body system: Hair

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Synopsis

Source of validity: Scientific
Rating (out of 5): 3

Hydrolyzed keratin is a common ingredient in hair care products, particularly shampoos, conditioners, and treatments aimed at strengthening and repairing damaged hair. Keratin is the primary structural protein in hair, and hydrolyzed keratin refers to keratin that has been broken down into smaller peptides, which are believed to more easily penetrate the hair shaft.

Scientific evidence supporting its use is moderate. In vitro and ex vivo studies have shown that hydrolyzed keratin can temporarily improve hair’s mechanical properties, such as elasticity and tensile strength, by filling in gaps in the cuticle caused by physical or chemical damage. Some small clinical studies and cosmetic industry-sponsored research indicate that products containing hydrolyzed keratin may reduce hair breakage and improve smoothness or shine, although these effects are often temporary and last only until the next wash.

However, the evidence is not robust. There is a lack of large, independent, peer-reviewed clinical trials demonstrating long-term benefits or significant biological effects beyond superficial conditioning. Most claims rely on laboratory research or studies with limited sample sizes. Still, the mechanism of action—binding of hydrolyzed proteins to damaged hair—has some scientific plausibility. As such, hydrolyzed keratin is scientifically validated to a moderate degree for supporting hair structure and appearance, but not for altering underlying hair growth or fundamentally changing hair health.

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Other body systems supported by Hydrolyzed keratin

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Products containing Hydrolyzed keratin

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