What are the benefits of polyglutamic acid for your skin?

Polyglutamic acid or PGA is a hydrosoluble peptide from the polymerisation of glutamic acid extracted from the fermentation of soybeans. It helps to fight dehydration in several ways.

First, it forms a microscopic film, called a microgel, at the surface of the epidermis. This swells when it comes into contact with water, and captures H2O molecules. PGA is able to hold up to 5,000 times its weight in water. As a comparison, hyaluronic acid can hold up to 1,000 times its weight in water. A study from 2014 shows that PGA has a more hydrating effect than hyaluronic acid.

Next, PGA boosts the production of natural moisurising factor (NMF) molecules. As a reminder, in the stratum corneum, water is retained by hygroscopic substances that form during epidermal differentiation. Several studies have shown that polyglutamic acid can boost production of some of these molecules, including pyrrolidone carboxylic acid (PCA), lactic acid and urocanic acid.

Finally, PGA limits the effects of hyaluronidase, the enzyme responsible for the breakdown of hyaluronic acid in the skin. As a reminder, hyaluronic acid is a molecule that is primarily produced by fibroblasts in the dermis (the deepest layers of the skin), and which acts like a sponge to retain water. It helps to maintain the skin’s hydration and gives it that plumped, healthy look. As time goes by, our skin produces less, and of worse quality. At age 50, our stock of hyaluronic acid has reduced by half. This drastic drop leads to atrophy of the fatty pockets located deep in the dermis, causing fine lines and wrinkles on the surface of the skin. By inhibiting the activity of the enzyme hyaluronidase, polyglutamic acid prevents dehydration of the skin and the appearance of the signs of ageing.

Note: PGA helps to maximise skin hydration, but can’t penetrate deeply because of its high molecular weight. Its effectiveness is limited to the upper layers of the skin. Hyaluronic acid has a low molecular weight, so is highly recommended for deeply hydrating the skin.

Skin ageing is due to intrinsic factors like a reduction in skin cell renewal, changes in the molecules which make up the dermis (hyaluronic acid, collagen), and the weakening of fatty and muscular tissue which starts to sag. Outside factors and lifestyle choices can accelerate the process (bad diet, smoking, excessive alcohol consumption, sun exposure, stress, lack of sleep…). Faced with these issues, the skin starts to wrinkle, it gets dryer, pigmentation marks can appear alongside dilated blood vessels. As the epidermis changes, it gets thicker or thinner depending on the person.

The first wrinkles that appear at around age thirty are usually dehydration wrinkles (generally around the eyes and/or on the forehead). Polyglutamic acid helps to slow this process thanks to its hydrating action, as above. Plus, a study has shown polyglutamic acid’s ability to more significantly strengthen the skin’s elasticity than collagen or hyaluronic acid when applied topically.