Polyglutamic acid, an active ingredient that prevents and smooths wrinkles?

The polyglutamic acid is a peptide made up of glutamic acid chains. Traditionally, this acid was recognized for its nutritional properties. Indeed, it is the main component of nattō, a traditional Japanese dish made from fermented soybeans. In recent years, several studies have focused on the moisturizing properties of polyglutamic acid, which has led to broadening its use and incorporating it into cosmetic formulations. The polyglutamic acid is generally used at concentrations between 0.3 and 3%, although there is no official limit in European regulations.

Regarding its effect on wrinkles and fine lines, this has been relatively understudied. However, we can mention a recent study conducted with a cream containing cucumber and polyglutamic acid. After daily application for several weeks by panelists, an average reduction of facial wrinkles by 24.97% was recorded, along with a 7.67% increase in skin elasticity. The number of participants and the duration of the study were not disclosed, making it difficult to draw precise conclusions about the tightening effects of polyglutamic acid. These results are nonetheless encouraging and call for further research to confirm the benefits of polyglutamic acid in preventing and targeting skin aging.

The effect of polyglutamic acid on skin aging is believed to be based on two mechanisms:

• Polyglutamic acid could potentially "plump" fine dehydration lines.

  The moisturizing properties of polyglutamic acid could be beneficial in preventing and smoothing dehydration fine lines. Indeed, this biopolymer has the ability to absorb water and form a microgel that retains moisture in the stratum corneum and limits transepidermal water loss. Its water retention capacity is indeed impressive: polyglutamic acid can retain up to 5,000 times its weight in water. For comparison, the hyaluronic acid, often considered the ultimate moisturizing active, can retain up to 1,000 times its weight in water. This hydrating ability of polyglutamic acid is relevant in combating dehydration fine lines, these thin lines that form when the skin is lacking water.

• Polyglutamic acid inhibits the enzyme hyaluronidase.

  Polyglutamic acid has another advantage against wrinkles. Studies in vitro have shown that it can inhibit the activity of hyaluronidase, the enzyme responsible for the degradation of hyaluronic acid present in our skin, contributing to its hydration and softness. However, over the years, the hyaluronic acid content in the dermis decreases. On average, we lose about 6% of hyaluronic acid per decade starting from our twenties. Thus, by the age of 50, our hyaluronic acid reserves have halved. This phenomenon partly explains the drying of the skin over time, as well as its sagging. By reducing the action of hyaluronidase, polyglutamic acid could therefore have a protective effect on the hyaluronic acid contained in our dermis, thus helping to prevent the appearance of age-related signs.