Copper peptides grew hair follicles in a dish. On scalps, the evidence is thin

AHK-Cu and GHK-Cu are tiny copper-carrying peptides. GHK-Cu is a familiar skin-care ingredient; AHK-Cu is marketed mainly for hair.

The key lab study, from 2007, used human hair follicles kept alive outside the body. AHK-Cu made them lengthen, and made dermal papilla cells, which drive hair growth, multiply. It also shifted markers of cell death in a protective direction, although the drop in the number of dying cells was not statistically significant.

The only placebo-controlled trial on scalps we found involving one of these peptides tested something else: a complex of GHK with 5-aminolevulinic acid. Forty-five men with male pattern hair loss applied one of two strengths, or a placebo, once a day for six months.

Hair counts rose by 52.6 and 71.5 hairs on the two strengths, compared with 9.6 on placebo. Hair length and thickness did not differ between the groups, and no side effects were reported. With about 15 men per group and a combination product, the trial can’t show what GHK contributes on its own.

Established hair-loss treatments have far larger trials behind them. For copper peptides, the step from a dish to a scalp hasn’t been properly tested.

Copper-peptide research materials, where listed, are in the research shop for laboratory use.