Another day, another new skin-care ingredient—it’s a tale as old as, well, moisturizer. But while many buzzy, up-and-coming actives tend to have more hype than hard data behind them, polyglutamic acid for skin is one of the few trends that actually has some credibility to back up its efficacy. Some even claim that it has quadruple the hydrating power of hyaluronic acid—able to hold up to 4,000 its weight in water—and while that’s not exactly true, there is a lot to love about it. (Long story short: That was in a lab setting, per one study, but there’s never been a head-to-head comparison between hyaluronic and polyglutamic acids in skin.)
For the uninitiated, polyglutamic acid (or PGA) is a peptide chain of glutamic acid, a type of amino acid, that’s derived from fermented soybeans. “It acts primarily as a humectant, binding and retaining water at the skin’s surface, like a hydrating sponge that leaves skin feeling softer and smoother,” says Taryn Huizenga, MD, a board-certified dermatologist in New York, NY. That’s why you may often spot it in hydrating serums and peptide formulas on the shelf.
Vogue’s Favorite Polyglutamic Acid Products:
PGA is also relatively large—which in this case, is a big bonus. “Because the molecule is so big, it mostly stays on the surface, where it leaves a light, flexible film that helps slow down water loss,” says Aderonke Obayomi, MD, a board-certified dermatologist in New York City. So it both pulls water into the surface layers of skin and, by forming that film, keeps water from evaporating. As a result, “what you actually see is skin that looks smoother and plumper and feels more comfortable, and fine lines caused by dehydration look softer,” she says.
There’s another advantage to be had with PGA. In addition to its hydrating properties, “it also inhibits hyaluronidase, the enzyme that breaks down your skin’s own hyaluronic acid,” says Asmi Berry, DO, a board-certified dermatologist in Los Angeles, CA. “So it’s not just hydrating. It’s helping protect the hydration you already have.” (That said, that’s mostly drawn from laboratory evidence, and there’s still a need for clinical evidence to show that this happens in the skin.)
