The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline 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 The Human Tripeptide GHKCu in Prevention of Oxidative Stress and Degenerative Conditions of Aging: Implications for Cognitive Health Pickart 2012 Oxidative Medicine and Cellular Longevity Wiley Online Library GHK Cu Peptide Benefits for Skin and Hair LIVV Natural GHK Cu Peptide Therapy for Radiant Skin by Desert Mobile The naturally occurring peptide GHK reverses age related fibrosis by modulating myofibroblast function He Aging Pathobiology and Therapeutics