GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? GHK Cu: The Regenerative Peptide for Skin, Hair, and Healing Pulse & Remedy 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 Rigid flexible nanocarriers loaded with active peptides for antioxidant and anti inflammatory applications in skin ScienceDirect