What should we know about glycogen?

The glycogen used in cosmetics is most often of plant origin and is obtained by extraction from corn or wheat. These are rich in starch, a macromolecule with a chemical structure similar to that of glycogen. In the case of corn, for example, the grains are first mechanically ground by a press to release the starch they contain. The extract is then subjected to centrifugations and filtrations, allowing the separation of the starch from the proteins and fibres of the plant.

Once isolated, the starch undergoes enzymatic reactions and is transformed into glycogen. The amylolytic enzymes of the amylase type are generally used to hydrolyse the glycosidic bonds of the starch, which releases glucose molecules. These are then polymerised to form glycogen chains under the action of other enzymes such as glycogen synthase. Finally, the obtained glycogen is purified by filtration to remove impurities.

When applied topically, glycogen primarily provides the skin with hydration. Indeed, this hydrophilic molecule is capable of retaining water on the surface of the epidermis to prevent it from evaporating. Glycogen thus strengthens the hydrolipidic film, playing a protective role, and limits water loss. It is particularly used to formulate care products for dry skin or for those wishing to prevent skin ageing. Hydration is indeed one of the key factors for supple and plump skin.

In addition to its hydrating effects, glycogen could potentially reduce the appearance of established wrinkles. Indeed, a non-independent study conducted with four individuals recently demonstrated that the twice-daily application of a cream containing 0.1% glycogen could reduce crow's feet wrinkles by an average of 42% and forehead wrinkles by an average of 54.9%. This research also involved 30 volunteers with age spots. The same protocol was followed and an improvement in pigmentation of an average of 30% was noted. However, as this was a non-independent study carried out with a relatively small number of people, caution should be exercised when considering the firming and brightening effects of glycogen.

Overall, the scientific literature indicates a lack of major risk associated with the cosmetic use of glycogen. Indeed, the inclusion of this active ingredient as a humectant in formulations does not result in redness, irritation or other adverse events. Glycogen is also entirely suitable for sensitive skin and does not present any particular incompatibility. Furthermore, its concentration in cosmetic products is not subject to any restrictions.

Nevertheless, even though glycogen is a gentle active ingredient, it is advisable to perform a tolerance test before using a cosmetic product for the first time to prevent the risk of allergies and side effects. To do this, apply a small amount of the product to the inside of your elbow, on your wrist or behind your ear and wait 24 to 48 hours to observe any potential skin reaction. Furthermore, always ensure to follow the user instructions of cosmetic products.