Glycolic acid is a type of alpha hydroxy acid (AHA) that, like other ingredients in the category, can act as a water-binding agent and, when properly formulated and used in concentrations of 5% or more, as an exfoliator. While there are several other types of AHA, glycolic acid is by far the one with the most research supporting its effectiveness.
In its exfoliating capacity, it can help remove dead skin to renew the skin's surface, resulting in the improvement of several signs of aging, including sun damage, uneven tone, rough, flaky patches, fine lines and wrinkles. These benefits can be achieved by choosing a leave-on AHA exfoliant that contains 5-10% glycolic acid when used as the sole exfoliating acid. It must also be formulated at a pH value between 3-4, where optimal exfoliation occurs.
Studies also show that glycolic acid significantly increases skin hydration. It does this by helping the skin produce substances such as mucopolysaccharides, which help with hydration by increasing the skin's natural hyaluronic acid content, which in turn increases resilience and improves texture.
An exciting new note about glycolic acid: New research shows that it may even protect the skin from UV damage (in addition to reducing its harmful aftereffects), although more research needs to be done (and of course it doesn't replace the need for sunscreen). It's worth noting that most AHA products carry a warning about unprotected sun exposure, as the way AHAs exfoliate exposes fresh new skin that may be more susceptible to sun damage.
Glycolic acid occurs naturally in sugar cane, but is most effective when synthesized in a laboratory, where its strength and concentration are optimized for use in skin care. Using plant sugars, such as sugar maple, for their glycolic acid content is an option, but the majority of it rhymes for efficiency, purity, stability and pH, all essential to get effective glycolic acid products. https://www.paulaschoice.com/ingredient-dictionary/ingredient-glycolic-acid.html?q=glycolic%20acid&fdid=ingredients