GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? The potential of GHK as an anti aging peptide GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? GHK Cu Copper Peptide Hair & Scalp Serum GHK Cu may Prevent Oxidative Stress in Skin by Regulating Copper and Modifying Expression of Numerous Antioxidant Genes 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