Amazon.com: GHK Cu Copper Peptide Powder 99.7%+ Pure Cosmetic Grade Ingredient for DIY Serums, Creams & Scalp Tonics Supports Collagen & Fuller Hair (1g) : Beauty & Personal Care Amazon.com: GHK Cu Copper Peptide Powder 99.7%+ Pure Cosmetic Grade Ingredient for DIY Serums, Creams & Scalp Tonics Supports Collagen & Fuller Hair (1g) : Beauty & Personal Care PCL GHK CU 75mg PekCura Labs GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with Frontiers Copper toxicity and deficiency: the vicious cycle at the core of protein aggregation in ALS