Bioactive Nutritional Macromolecules Supporting Hair Structure, Density, and Growth: A Comprehensive Review

This review examines the roles of five macromolecules—type I collagen, elastin, keratin, ceramides, and melanin—in enhancing hair structure, density, and growth. Type I collagen and elastin support the hair follicle's extracellular matrix, promoting growth and reducing breakage. Keratin improves tensile strength and reduces shedding, with clinical studies showing a 30–50% decrease in hair loss. Ceramides maintain moisture balance and structural integrity, while melanin provides UV protection and maintains color. Clinical trials confirm these macromolecules' effectiveness in improving hair health, despite some limitations in study populations and sample sizes. The evidence supports their combined use to enhance hair strength, resilience, and overall health.