What is the role of glycogen in topical application?

A polymer of glucose, glycogen is a hydrophilic compound with good water capture and retention capabilities. When applied topically, this molecule supports the hydrolipidic film present on the surface of the epidermis and helps to limit insensible water loss, also known as TEWL. Moreover, it is also possible that glycogen stimulates the production of ceramides, the lipids found in the horny layer and forming the skin's waterproof barrier. Indeed, an in vitro study revealed that incubating keratinocytes with 2% glycogen increased the cellular quantity of ceramide NS (ceramide 2) by 3 times compared to the control. However, it is not certain that topical application of glycogen can have this effect on ceramide production as it is a complex with a significant molecular weight and has difficulty penetrating the skin barrier.

The moisturizing virtues of glycogen are particularly beneficial for individuals with dehydrated skin, prone to feelings of tightness, or wishing to prevent dehydration fine lines. A clinical trial was recently conducted with about thirty individuals with dry skin. These volunteers applied a cream containing 0.1% glycogen twice a day for 42 days. At the end of the study, skin hydration was measured using a corneometer. On average, it increased by 45%, indicating the hydrating potential of glycogen. However, as this was not an independent study, it would be beneficial for further research to be conducted to confirm these results.

Glycogen could also have an effect on skin aging. Indeed, in addition to its moisturizing properties, this active ingredient could stimulate the activity of fibroblasts, the cells responsible for the production of collagen, elastin, and hyaluronic acid. These are three key molecules for the skin, the gradual decrease of which in connective tissues greatly contributes to skin sagging and loss of firmness. Indeed, collagen and elastin are proteins found in the extracellular matrix of the dermis and ensure its cohesion. Hyaluronic acid, on the other hand, is responsible for skin hydration and acts like a sponge to retain water in skin tissues. However, it is necessary to exercise caution regarding the effects of glycogen on fibroblasts as these have only been demonstrated in an in vitro study so far.

The non-independent clinical trial mentioned earlier also examined the effects of glycogen on wrinkles. This time, four volunteers with signs of photoaging applied the cream with 0.1% glycogen twice a day. After 42 days, a mean reduction of 42% in crow's feet wrinkles and 54.9% in forehead wrinkles was measured. It would again be interesting if the results of this study were corroborated by independent scientific research involving more volunteers.

Finally, glycogen could potentially mitigate dark spots. These marks, left by sun exposure, hormonal changes, or inflammatory phenomena, are very difficult to fade and disrupt the uniformity of the complexion. The previously mentioned study examined the effects of glycogen on hyperpigmentation marks. 30 individuals with pigmentation irregularities applied a cream containing 0.1% glycogen twice a day. After 42 days, the researchers noted a 30% improvement in pigmentation. However, it is difficult to make a definitive statement about the depigmenting properties of glycogen, as these have only been demonstrated in a single non-independent study. Moreover, the associated mechanism of action has not yet been elucidated.

• HALPRIN K. M. & OHKAWARA A. & al. Glucose and glycogen metabolism in the human epidermis. The Journal of Investigative Dermatology (1966).

• YATSUHASHI H. & others. Effects of Glycogen on Ceramide Production in Cultured Human Keratinocytes through Acid Sphingomyelinase Activation. Journal of Applied Glycoscience (2021).

• Supplier document.