[1] Section 503A of the Federal Food, Drug, and Cosmetic Act, 21 U.S.C
What GHK-Cu adds to the formulation: Gene expression modulation across hundreds of genes including collagen genes (Type I, III), tissue inhibitors of metalloproteinases, anti-inflammatory mediators Collagen synthesis stimulation, specifically Type I and Type III collagen the structural proteins of skin, connective tissue, and many other tissues Anti-inflammatory signaling through investigated effects on TNF-, IL-6, and NF-B pathways Copper-peptide chemistry effects including cofactor activity for skin-relevant enzymes Skin-research and hair-research applications (the GHK-Cu literature in these areas is substantial) For the GHK-Cu deep-dive, see Copper Peptides Explained
You can simplify the difference by thinking of copper peptides as peptides that help support the follicles communication network, while keratin peptides provide targeted structural support for the hair itself
Questions about liver safety are also common among individuals researching peptide therapy