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, Relief of ovalbumin induced airway remodeling by the glycyl l histidyl l lysine Cu2+ tripeptide complex via activation of SIRT1 in airway epithelial cells ScienceDirect Your body made this peptide every day until you turned 30. Then it stopped. GHK Cu (copper peptide) is a naturally occurring tripeptide discovered in 1973. At age 20, your plasma levels sit OBM Geriatrics The Effect of the Human Plasma Molecule GHK Cu on Stem Cell Actions and Expression of Relevant Genes GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective?