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, The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline Frontiers Exploring the beneficial effects of GHK Cu on an experimental model of colitis and the underlying mechanisms 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