The Peptide Craze Ground Truths GHK Cu Copper Peptide: Dosage, Before and After Results, and How It Works Perfect B 5 things that might surprise you about GHK Cu 1 Your body already makes it. GHK Cu is a naturally occurring copper peptide found in plasma, saliva, and urinebut levels decline as we age. GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? Frontiers Exploring the beneficial effects of GHK Cu on an experimental model of colitis and the underlying mechanisms