GHK Cu is a naturally occurring copper peptide found in the body that plays a key role in skin regeneration, healing, and overall skin health. As we age, levels declinewhich is where topical What Is GHK Cu? The Copper Peptide That Rejuvenates Skin 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 GHK Cu Peptide The benefits, side effects, and more [2026]