The potential impact of whey protein on hair: A literature review of hormonal, metabolic, and nutrient sensing pathways

Background Whey protein (WP) is one of the most commonly used dietary supplements worldwide, yet, possible impact on hair remains unclear. Direct effects of WP on hair have not been well defined, and the available evidence is inconsistent and indirect. Objective To explore and synthesize the current evidence regarding WP use, focusing on its effect on hair, to highlight areas where evidence is lacking, and to outline the mechanisms that may connect WP use to hair. Methods A comprehensive review of the literature was conducted using PubMed and EMBASE. Two independent reviewers screened the abstracts of experimental, clinical, and observational studies addressing WP use; relevant articles were extracted and discussed. Results Limited human trials and mechanistic studies suggest that WP possible effects are mediated through amino acid composition, insulin-like growth factor 1 (IGF-1) modulation, and hormonal changes; however, clinical trials are lacking. Conclusion Understanding the relationship between WP and hair is essential given the global prevalence of protein supplement use. More focused clinical research is needed to determine whether WP plays a role in hair growth or loss, and to guide evidence-based counseling for patients who regularly use or want to use WP.