Topical collagen: an ally against wrinkles.

Collagen is a protein of great importance for the skin. Present in the form of fibres, it acts as a binder in the extracellular matrix of the dermis and helps to maintain its structure, thus ensuring the suppleness and firmness of the skin. However, its production begins to slow down around the age of 25, at a rate of about 1% per year. Additionally, collagen fibres tend to fragment and become disorganised over time, which promotes the appearance of wrinkles and skin sagging.

To combat the signs of aging, an external supply of collagen appears to be relevant.

When applied topically, collagen primarily offers moisturizing benefits. Often combined with hyaluronic acid, this highly skin-compatible ingredient forms a film on the skin's surface that attracts and retains water molecules. In doing so, collagen strengthens the hydrolipidic film, a water/oil substance that aims to protect the skin, which helps to prevent dehydration fine lines. As their name suggests, these fine lines form when the epidermal barrier is weakened due to significant water loss.

Furthermore, studies have shown that hydrolysed collagen has antioxidant effects, which depend on the size of the peptides: the smaller they are, the better their ability to donate an electron to stabilise free radicals. The neutralisation of oxidative stress plays an important role in the prevention of wrinkles. Indeed, by oxidising endogenous collagen and elastin fibres, free radicals alter their structure and weaken their ability to optimally support the skin.

Finally, unlike native protein, collagen peptides can penetrate the epidermis and stimulate the proliferation and activity of fibroblasts, the skin cells responsible for the production of collagen, elastin, and glycosaminoglycans. By strengthening the extracellular matrix of the dermis, collagen peptides help maintain smooth and firm skin for longer and delay the appearance of wrinkles.

A clinical trial aimed to highlight the firming properties of collagen peptides when applied topically. For this purpose, 22 women with visible periorbital and glabellar wrinkles applied a collagen solution to their faces twice daily. After 4 weeks, the researchers observed several improvements, which they deemed significant, in the participants' wrinkles, as summarised in the table below. However, these improvements appear to be quite minimal. Another limitation of the study is the relatively small number of participants.