GHK Cu Dosage and Protocol: A Medical Provider's Guide to the 30 Day Cycle Perfect B GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? By age 30, your skin produces about 25% less collagen. By 40, that number can reach 40%. This decline affects more than just how your skin looks. It changes how it heals, GHK Cu, commonly known as copper peptides, are found naturally within the human body where they play a vital role in skin repair and maintenance. Copper peptides support optimal skin function by helping