Fish protein, especially in the form of hydrolyzed fish collagen, is increasingly used in supplements and cosmetic products aimed at supporting hair health. The scientific rationale is primarily based on the amino acid profile of fish protein, which is rich in essential amino acids like glycine, proline, and hydroxyproline. These are important for the synthesis of keratin, the main structural protein in hair. Some in vitro and animal studies suggest that collagen peptides can stimulate dermal papilla cells, which play a role in hair follicle growth. Additionally, fish protein is a source of nutrients like omega-3 fatty acids, which have been linked in some studies to reduced hair shedding and improved hair density due to their anti-inflammatory properties.

However, direct human clinical evidence that fish protein supplementation significantly improves hair growth or health is limited. Most available studies are small, short-term, or use formulations containing other active ingredients, making it difficult to isolate the effects of fish protein alone. While the biological plausibility is moderate and there is some supportive preliminary data, robust randomized controlled trials in humans are lacking. Thus, while there is a scientific basis for the use of fish protein in supporting hair health, the overall strength of the evidence is modest at present.