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 GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? Expression and Purification of Recombinant GHK Tripeptides Are Able to Protect against Acute Cardiotoxicity from Exposure to Waterborne Copper in Zebrafish GHK Cu Copper Peptide in LA 3,356+ Reviews Your body made this peptide every day until you turned 30. Then it stopped. GHK Cu (copper peptide) is a naturally occurring tripeptide discovered in 1973. At age 20, your plasma levels sit How GHK Peptide Works Signaling GHK acts as a switch for skin repair: Interacts with adenosine receptors reduces inflammation Activates MAPK ERK, PI3K Akt, TGF pathways Stimulates fibroblasts & keratinocytes boosts collagen, elastin