GHK

GHK, short for glycyl-L-histidyl-L-lysine, is a small peptide composed of three amino acids joined in sequence. It occurs naturally in human plasma, saliva, and urine, and it has a strong affinity for copper(II) ions, with which it forms a tightly bound complex called GHK-Cu; in this complex the copper is held in a way that quiets its usual chemical reactivity, allowing the peptide to carry copper to and from cells in a controlled fashion ^[3]. A frequently cited observation is that the amount of GHK in human plasma is relatively high in young adults and declines substantially with age, a change that has prompted interest in its possible connection to the aging of tissues ^[3].

The peptide was discovered by the biochemist Loren Pickart, who in 1973 reported a substance in human serum that helped aging liver tissue behave more like younger tissue; the active factor was isolated from the blood protein albumin and, in 1977, identified as the tripeptide glycyl-histidyl-lysine ^[1][2]. Later work established that much of its biological activity is bound up with its copper complex, and research over the following decades broadened from tissue culture to studies of skin, wound repair, and gene expression ^[3].

GHK and GHK-Cu have been studied for a range of regenerative and protective actions ^[3]. In laboratory and animal work they promote wound healing and tissue remodeling, stimulate the production of collagen, elastin, and glycosaminoglycans by skin fibroblasts, and support the growth of blood vessels and nerve fibers. Reported activities also include antioxidant and anti-inflammatory effects and the modulation of a large number of human genes, which has been proposed as an explanation for the peptide's varied effects ^[3]. Much of this evidence comes from cell and animal studies rather than from large clinical trials in people.

In practice, GHK-Cu is used mainly as an ingredient in cosmetic and skin-care products, where it is marketed for purported effects on skin firmness, wrinkles, and repair. It is not an approved pharmaceutical, and its wound-healing and other medical applications remain largely at the research stage. Because it is a naturally occurring human peptide, it is generally regarded as well tolerated in topical use, though rigorous clinical data are limited ^[3].

GHK (typically as the copper complex GHK-Cu) has a clean documented safety record, with most users reporting no systemic adverse effects at standard cosmetic and research doses. When applied topically, a minority (roughly 5-10% of new users) experience mild transient irritation such as redness, tingling, or slight burning that usually resolves within a week or two. Copper toxicity is considered extremely unlikely at typical doses because the body tightly regulates and excretes copper, leaving a very wide margin before toxic exposure. The main documented contraindication is any inherited or acquired disorder of copper handling, particularly Wilson's disease, where copper accumulation is a genuine risk.