Hydrolyzed gelatin, a form of collagen broken down into smaller peptides, is often promoted as a supplement for supporting hair health. Scientifically, gelatin is rich in amino acids, especially glycine and proline, which are components of keratin, the primary protein in hair. Some small-scale studies and animal research suggest that collagen peptides may help increase hair thickness and strength, likely due to improved amino acid availability and potential support for the hair follicle structure. However, direct evidence in humans regarding hydrolyzed gelatin’s effect on hair growth, thickness, or overall hair health is limited and often of low quality. Most human studies have focused on collagen peptides rather than gelatin specifically, and results are mixed or preliminary.

The rationale for using hydrolyzed gelatin for hair is partly extrapolated from its general benefits for skin and nails, where there is somewhat stronger evidence. Traditional use also exists, but the modern scientific foundation is still emerging, with most clinical trials being small, uncontrolled, or sponsored by supplement manufacturers. Therefore, while there is a plausible mechanism and some early supportive findings, the scientific evidence is not robust. The overall strength of evidence supporting hydrolyzed gelatin for hair health is modest, meriting a rating of 2 out of 5.