While product labels often make outrageous claims and beauty buzzwords come and go faster than a new haircut, hard research and expert opinions agree that copper peptide does encourage hair growth. This naturally occurring ingredient appears in everything from supplements to skin creams, but its triple amino-acid content is especially beneficial to hair follicles.

In 2007, “Archives of Pharmacal Research” published a study on the effect of copper peptide -- also known as GHK-Cu tripeptide -- on human hair growth. The study found that copper peptide does stimulate the growth of hair follicles, likely due to stimulation of dermal papilla cells. An older study from a 1993 issue of the “Journal of Investigative Dermatology” corroborates these findings, noting that copper peptide contributes to the enlargement of hair follicles.

Loren Pickart, biochemist and founder of the Skin Biology line of hair- and skin-care products, offers a few explanations for the potential perks of copper peptides, when it comes to a healthy coif. Pickart notes that -- in addition to increasing follicle size --copper ions inhibit the production of dihydrotestosterode, or DHT, a chief cause of genetically motivated hair loss. Additionally, copper peptide encourages the production of blood capillaries, which help carry hair-essential nutrients to the follicles.

While much of the buzz around copper peptide focuses on stimulating hair growth, the copper complex also offers some benefits for basic hair health. Dermatologist Dennis Gross champions it as an ingredient in topical scalp serums; speaking to "Harper's Bazaar," he says that because copper peptide stimulates collagen production, it “helps promote thick hair and volume” in as little as two weeks with regular application.

A study in the “Journal of Investigative Dermatology” suggests that copper peptide offers hair growth roughly equivalent to that of a 5-percent minoxidil solution, one of the few hair-growth ingredients approved by the U.S. Food and Drug Administration. Copper peptide also acts as an antioxidant that benefits hair health for existing locks, according to research published in the “Journal of Photochemistry and Photobiology” in 2012. It bolsters hair's fiber integrity, protects it from sun damage and helps preserve color and shine.