Does GHK Cu Really Work? 40 Years of Research Reviewed GHK Cu (copper peptide) is a science backed anti aging compound that supports collagen production, skin regeneration, and overall skin health. Used in both topical serums and subcutaneous Copper Peptide Duo GHK Cu Anti Aging Serum & Moisturizer 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,