GHK Cu may Prevent Oxidative Stress in Skin by Regulating Copper and Modifying Expression of Numerous Antioxidant Genes Defy GHK Cu (glycyl L histidyl L lysine) is a naturally occurring copper binding peptide found in human plasma. As levels decline with age, so may its support of the biological processes involved in collagen production, skin Fitish Most people don't know GHK Cu by name. Their face does. It's the peptide your body uses to signal collagen production, repair tissue, Instagram Best Copper Peptide Serum The top 4 options of 2026