What Are the Benefits of Polyglutamic Acid on the Skin?

Polyglutamic acid or PGA is a water-soluble peptide derived from the polymerization of glutamic acid extracted from the fermentation of soybeans. This compound fights against skin dryness at different levels.

First of all, it forms a microscopic film on the surface of the epidermal tissue called a microgel. This molecular arrangement swells on contact with water and traps the H2O molecules. Through this mode of action, PGA is able to retain up to 5,000 times its weight in water. In comparison, hyaluronic acid retains up to 1,000 times its weight in water. A 2014 study revealed that PGA had a more hydrating effect than hyaluronic acid.

Secondly, PGA boosts the production of molecules making up the natural moisturizing factor (NMF). As a reminder, in the stratum corneum, water is retained thanks to hygroscopic substances that are formed during epidermal differentiation. Thus, several studies have demonstrated the ability of polyglutamic acid to boost the production of some of these molecules, including pyrrolidone carboxylic acid (PCA), lactic acid and urocanic acid.

Finally, PGA limits the activity of hyaluronidase, the enzyme responsible for the reduction of hyaluronic acid present in the dermal tissue. As a reminder, hyaluronic acid is a molecule mainly produced by the fibroblasts of the dermis (deep layer of the skin) which acts like a sponge and retains water. It ensures the hydration of the skin and gives it a plumped-up appearance. Over the years, not only does its content decrease but its quality also changes. Thus, at the age of 50, the stock of hyaluronic acid has decreased by half. This drastic drop leads to an atrophy of the fatty pockets located in the depth of the dermis, which is the cause of the appearance of wrinkles and fine lines on the skin's surface. By inhibiting the activity of the enzyme hyaluronidase, polyglutamic acid prevents the dehydration of the skin and the appearance of the signs of aging.

Note: Although it helps to maximize the hydration of the epidermis, PGA cannot act on the deeper layers of the skin because its molecular weight is too high. Its action is limited to the superficial layers of the skin. Low molecular weight hyaluronic acid is more suitable for deep moisturizing of the skin.

Skin aging is the result of internal factors, such as a decrease in the rate of cell renewal, a change in the composition of the dermis and the molecules that make it up (hyaluronic acid, collagen, etc.) and the decreasing of fatty and muscular tissue that no longer plays its supporting role. External factors that depend on lifestyle choices can greatly accelerate the process (poor diet, smoking, excessive alcohol consumption, sun exposure, stress, lack of sleep, etc.). As a result, wrinkles appear, the skin becomes drier, pigment spots may appear, as well as dilated vessels. In addition, the epidermis changes, becoming thicker or thinner depending on the person.

The first wrinkles that appear around the age of 30 are most often dehydration wrinkles (generally around the eyes and/or on the forehead). Polyglutamic acid helps to slow down this process thanks to its moisturizing action, described in the previous paragraph. In addition, a study has demonstrated the capacity of polyglutamic acid to reinforce the elasticity of the skin more significantly than collagen and hyaluronic acid in topical application.