What are the benefits of collagen for the skin?

Naturally present in the body, collagen is the most abundant protein in the human body: it accounts for about 25% of the proteins recorded in the body. Produced by fibroblasts, it provides a mechanical resistance to stretching and a structure to many of the body's connective tissues, which is why collagen is found, among other things, in the skin, muscles, bones, ligaments, tendons, hair...

There exist 28 types of collagen each with different properties depending on where it is located, of which type I is the major component of the extracellular matrix of the dermis, representing 80 to 90% of the total collagen. It is characterised by three polypeptide chains organised in a helical manner, each composed of a thousand amino acids linked together by disulfide bridges to form patterns (called sequences). Glycine is the most represented amino acid, but it is also rich in proline and hydroxyproline.

Collagen holds significant importance for the skin. Present in the form of fibres, it ensures tissue regeneration, provides a high degree of elasticity, imparts flexibility and resilience, and acts as a binder between skin cells, helping to maintain its structure. The issue is that as the years pass, collagen synthesis slows down. This loss can begin around the age of 25, and the body can lose approximately 1% of collagen per year, and progressively up to 25% per year. Thus, by the age of 80, we have lost 75% of collagen compared to young adults. Moreover, over the years, collagen fibres become rigid, fragmented and disorganised.

These phenomena promote the appearance of wrinkles, loss of firmness and elasticity in tissues, and sagging of the skin. On the other hand, a lack of collagen in the skin results in an irregular skin texture: the skin loses its radiance and the complexion becomes less uniform. Unprotected exposure to UV rays, smoking, air pollution, not to mention the role of diet with glycation (the binding of sugars to collagen) leading to a stiffening of this protein, all contribute to this premature degradation of collagen.

To slow down skin ageing, the external supply of collagen can be beneficial. Thus, it can be used in cosmetics to compensate for the decrease in production associated with age, and thereby help to reduce the depth of wrinkles and improve the appearance of the skin. Topically applied, collagen performs an action:

• Anti-radical: studies in vitro have shown that collagen possesses potential antioxidant properties, meaning they are capable of neutralising free radicals, thereby mitigating the harmful effects induced by oxidative stress;

• Hydrating: Collagen aids in combating and preventing dehydration by forming a thin film on the surface of the epidermis, protecting the skin against insensible water loss and external aggressions. Furthermore, it has the ability to attract and retain water molecules in the tissues to hold water within them, thus maintaining a good hydration level in the epidermis. Finally, collagen also helps to increase cell-to-cell adhesion in the epidermis, which is involved in the structural integrity of the epidermis and the formation of the barrier;

• Restructuring: studies in vitro and in vivo have shown that hydrolysed collagen has the power to stimulate the body's natural production of the molecule, while reducing its destruction. Similarly, peptides derived from hydrolysed collagen stimulate the proliferation and activity of fibroblasts, which are the skin cells responsible for the production of collagen, elastin and glycosaminoglycans. Furthermore, the increase in cell-to-cell adhesion helps to maintain smooth and firm skin for longer. Thus, collagen delays the appearance of wrinkles, improves skin texture and its elasticity.

What are the terms of use?

Native collagen is a fibrous protein with a high molecular weight (300 kDa). Due to these characteristics, it cannot penetrate the epidermal barrier. However, to be properly assimilated and perform its functions, it must have a molecular weight between 2,000 and 6,000 Da, as the lower the molecular weight, the better the bioavailability.

To address this, the collagen is hydrolysed, meaning it is broken down into peptides composed of amino acids with lower molecular weights than the original molecule (approximately between 1,000 and 10,000 Da) to facilitate trans-epidermal penetration.