Most people think skincare works at the surface level. But healthy skin function starts much deeper than a temporary glow. GHK Cu is a naturally occurring copper binding tripeptide that is already found The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline GHK Cu is one of my personal favorites for a lot of reasons, but I can say without a doubt that it's use effectively stopped and reversed, my receiving hairline. However, there are GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link