The contribution of copper to the prevention of skin ageing.

As time passes, the skin slackens and grooves form on the face, creating wrinkles. These appear in various places, particularly on the forehead, around the eyes and around the lips. It's worth noting that we refer to these as wrinkles when the depth of the grooves exceeds 1 millimetre. If the grooves have a depth between 0.2 and 1 millimetre, they are considered as fine lines. Several factors contribute to the development of wrinkles.

• Internal causes.

  As we age, many biological mechanisms slow down, or even stop. This is particularly the case for cellular renewal and fibroblast activity, which gradually decrease over the years. These dermal cells are responsible for the synthesis of collagen, elastin and hyaluronic acid, molecules that respectively contribute to the suppleness, elasticity and hydration of the skin. The reduction in the level of these compounds in the dermis contributes to skin sagging and the appearance of wrinkles.

• External causes.

  The emergence of wrinkles is also promoted by certain external factors to the body, such as pollution, UV rays and smoking, elements that generate oxidative stress in the skin cells. This particularly damages the DNA, and collagen and elastin fibres. UV rays alone are responsible for about 80% of premature skin ageing.

Oxidative stress is one of the major causes of premature skin ageing. The free radicals are indeed harmful to the body and its constituents. Thanks to its antioxidant properties, copper can neutralise and eliminate them, thus protecting the collagen and elastin fibres.

Furthermore, studies have shown that the copper tripeptide Alanine-Histidine-Lysine-Copper (AHK-Cu) is capable of stimulating the production of superoxide dismutase (SOD), an antioxidant enzyme. SOD notably catalyses the dismutation of the superoxide ion O2- into oxygen O2 and hydrogen peroxide H2O2. These various mechanisms make copper an ally in preventing skin ageing.

Studies have also shown that copper has effects on the synthesis of collagen and elastin, the proteins that ensure the flexibility and firmness of the skin. More specifically, as an enzymatic cofactor, copper ensures the proper functioning of certain enzymes such as lysyl oxidase. This enzyme facilitates the bonding between lysine residues and aldehydes, thus enabling the formation of collagen and elastin in a reaction known as "cross-linking".

Beyond its role as an enzymatic cofactor, copper can also activate fibroblasts, the cells responsible for synthesising collagen and elastin in the dermis. In the presence of copper, fibroblasts are stimulated and secrete more structural proteins. Thanks to its various properties influencing the synthesis of collagen and elastin, copper is included in the formulation of many cosmetic treatments targeting skin ageing.

Some studies suggest that copper may also reduce the depth of existing wrinkles. One such study examined 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 assessed 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.

Another study focused on the effects of a gel composed of amino acids, copper, and hyaluronic acid. This was applied four times at weekly intervals to the faces of five participants. The depth of wrinkles was evaluated before and after the treatment: it was on average 0.067 mm at the start compared to 0.061 mm afterwards. The assessment of skin hydration also showed an improvement: it increased from 48.9% to 56%.

Please note : it is important to exercise caution regarding the effects of copper used in cosmetics on established wrinkles. Indeed, the first study was conducted using a pillowcase and not a skin care product, and the second involved only five people, which is very few. Moreover, the second study did not evaluate the action of copper alone but a mixture of copper, amino acids and hyaluronic acid.

• 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).

• SONG S. & al. Evaluation of the efficacy of an elastin-inducing composition containing amino acids, copper, and hyaluronic acid: Results of an open single-center clinical trial study. Cosmetics (2022).