What Are Alpha-Hydroxy Acids?
Alpha-hydroxy acids are a group of acid compounds, most often derived from plant-based sources. There are a variety of different ones out there, some of the most common of which include: glycolic (derived from sugarcane), lactic (derived from sour milk), citric (derived from lemons), and malic (derived from apples).
While they all act on the skin’s surface as chemical exfoliants, they differ in size, penetration, and potency. “The smaller the molecule, the deeper the penetration, and therefore, the more efficacious it is,” explains Nussbaum. However, on the flip side, increased efficacy can also mean an increased likelihood of irritation, particularly if your skin is already sensitive, to begin with. That’s why the type of alpha-hydroxy acid you choose, its concentration, and the product it comes in are all essential, but more on that in a minute.
Benefits of Alpha-Hydroxy Acids for Skin
By definition, any type of acid is going to exfoliate the skin, but AHAs go above and beyond that call of duty. Here are more benefits of AHAs.
- They’re a surface exfoliant: As skin cells die, they can often clump together and get stuck on top of the skin. Alpha-hydroxy acids dissolve the “glue” that holds them together, helping them to gently slough away, says Nussbaum. The result? Pretty much all of the things you want, namely increased radiance, a smoother texture, and fewer dark spots. This chemical exfoliation is what makes AHAs a good choice for those with sensitive skin, for whom physical exfoliation (AKA manual scrubbing) may result in redness and inflammation, Nussbaum adds.
- Increase collagen production: AHAs don’t just work on the epidermis; they can also have effects on the deeper layer of the skin (or the dermis). “Studies show that all of the AHAs promote collagen development to a certain extent; however, none more than glycolic acid,” explains Nussbaum, who adds that this is the AHA most often found in anti-aging products. And more collagen equals fewer lines and wrinkles.
- Hydrate: Glycolic acid, malic acid, and lactic acid are humectants, meaning they attract water to the skin. Lactic acid, in particular, is a top choice for those with dry skin, says Nazarian.
- Offer antioxidant benefits: Among the AHAs, citric acid, in particular, stands out for its antioxidant properties, making it a great pick for fighting free radical damage and lightening dark spots as well, Nazarian says.