Squalane + Copper Peptide (GHK Cu) Rapid Plumping Serum 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 Copper Peptide Serum Benefits: Complete Guide to GHK Cu Glimmer Goddess Viral claim says GHK Cu reset nearly 4,000 genes to a younger state and increased collagen production in a preclinical study. This refers to research on GHK Cu, a naturally occurring copper binding peptide that The Peptide Craze Ground Truths