GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? Growth Hormone and Aging Endotext NCBI Bookshelf Synergy of GHKCu and hyaluronic acid on collagen IV upregulation via fibroblast and exvivo skin tests Jiang 2023 Journal of Cosmetic Dermatology Wiley Online Library Top 9 GHK Cu Benefits for Skin, Hair, and Anti Aging GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with By age 30, your skin produces about 25% less collagen. By 40, that number can reach 40%. This decline affects more than just how your skin looks. It changes how it heals,