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 as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline GHK Cu Peptide: What It Does for Body Composition and Metabolic Health