The benefits of copper for the skin.

Studies have shown that copper possesses a antioxidant power that enables it to defend cells and cellular compounds against oxidative stress. This stress notably increases following exposure to UV rays or pollution and leads to the generation of free radicals. Copper protects skin cells from the damage of free radicals by stimulating the activity of superoxide dismutase (SOD). SOD is an antioxidant enzyme that catalyses the dismutation of superoxide anions into oxygen and hydrogen peroxide. The copper thus has a protective effect on the skin and helps to delay skin sagging and the appearance of wrinkles, phenomena correlated with oxidative stress.

Copper also has positive effects on the suppleness and elasticity of the skin. Indeed, this active ingredient is a cofactor of the enzyme lysyl oxidase, ensuring the bond between lysine residues and aldehydes, thus allowing the formation of collagen and elastin in a reaction known as "cross-linking". Research has also shown that copper is capable ofactivating fibroblasts, the cells in the dermis responsible for the synthesis of collagen and elastin. In the presence of copper, fibroblasts are stimulated and secrete more structural proteins. Thanks to these various properties, copper proves to be an ally in the prevention of skin sagging.

Some studies go even further, attributing to copper the ability to diminish already established wrinkles. One such study focused on the effects of a pillowcase containing 1% copper oxide by weight. Over eight weeks, 30 volunteers used this pillowcase and the condition of their skin was evaluated through 3D image analysis. The researchers estimated that the participants' crow's feet wrinkles had decreased by 17% at the end of the experiment, with no adverse effects observed.

Note : While the effects of copper in cosmetics on skin suppleness and elasticity are certain, caution should be exercised regarding its ability to diminish existing wrinkles. Indeed, the study mentioned above was not conducted with a cosmetic cream or gel, but with pillowcases. More research would be necessary to conclusively assert that copper in cosmetics reduces established wrinkles.

When incorporated in the form of copper PCA, this trace element is also recognised for its antibacterial and sebum-regulating properties. Copper PCA is often included in treatments for combination to oily skin, prone to imperfections. These imperfections are often due to one of the following three causes or a combination of the three: overproduction of sebum, bacterial colonisation by Cutibacterium acnes and hyperkeratosis. Often used in synergy with zinc PCA, copper PCA combats the first two factors and prevents both the obstruction of skin pores by sebum and bacterial proliferation.

The underlying mechanisms are still poorly understood , but it is suggested that copper PCA may be able to disrupt the metabolism of bacteria, thereby preventing their growth. In terms of its sebum-regulating action, it appears that copper PCA may be able to inhibit 5-α-reductase, the enzyme catalysing the transformation of testosterone into dihydrotestosterone (DHT). DHT acts by binding to a specific cytosolic receptor located in the sebaceous glands, which results in an increased production of sebum.

Some copper peptides are also recognised for their anti-inflammatory properties. Peptides are small proteins made up of short chains of amino acids. A peptide does not contain more than about twenty amino acids, unlike a protein. It has been shown that certain copper peptides are capable of inhibiting the release of the tumour necrosis factor TNF-α. This is a pro-inflammatory cytokine with direct and indirect effects that exacerbate inflammation. TNF-α acts in particular by releasing interleukins-1 and 6 (IL-1 and IL-6), other pro-inflammatory cytokines that enhance inflammation. By reducing the release of TNF-α, copper peptides help to soothe the skin and protect it from inflammation.

Copper, specifically copper gluconate, is a valuable ally for damaged or healing skin. It has indeed been shown that this active ingredient stimulates the synthesis of collagen and glycosaminoglycans by fibroblasts, a process essential for forming new tissues. Furthermore, copper stimulates angiogenesis, that is, the formation of new blood vessels from existing ones, which allows for better distribution of nutrients, oxygen, and growth factors necessary for healing.

• BOREL J. P. & al. Stimulation of sulfated glycosaminoglycan synthesis by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. Life Sciences (1992).

• BORKOW G. & al. Reduction of facial wrinkles depth by sleeping on copper oxide-containing pillowcases: a double blind, placebo controlled, parallel, randomized clinical study. Journal of Cosmetic Dermatology (2012).

• BORKOW G. Using copper to improve the well-being of the skin. Current Chemical Biology (2014).