Its 100% quackery, 100% useless and 100% dangerous in the wrong hands
Moreover, this genetic trait is due in part to a form of a gene (DRD 2 A1 allele) that prevents the expression of the normal laying down of dopamine receptors in brain reward sites (10, 11, 12)
Falling asleep faster and sleeping more deeply are the earliest reported effects
Zinc, copper, and manganese also play roles in connective tissue metabolism
Conversely, knockdown of FGF21 in mice fed a ketogenic diet significantly increases serum lipemia and cholesterolemia (87)
Since GHK-Cu carries copper, taking too much for too long may be a concern for people with liver issues, copper metabolism concerns, or pregnancy/nursing considerations