Defy GHK Cu (glycyl L histidyl L lysine) is a naturally occurring copper binding peptide found in human plasma. As levels decline with age, so may its support of the biological processes involved in collagen production, skin Why Collagen Loss Accelerates After 40: The Role of GHK Cu in Menopaus Pure & Cimple Say hello to your skin's new BFF GHK Cu is a powerful peptide that supports collagen production, speeds healing, improves hair growth, and helps fight visible signs of aging. This tiny molecule Growth Hormone and Aging Endotext NCBI Bookshelf