What are Alpha Hydroxy Acids?

Alpha Hydroxy Acids, or AHAs, are naturally occurring ingredients, although they also can be synthesized in a lab. They include glycolic acid, the most common AHA, which is made from sugar cane; lactic acid, which comes from dairy products and is generally known to be milder and therefore less irritating than glycolic acid; malic acid, which comes from apples and pears; citric acid from citrus fruits; and tartaric acid from grapes.

When alpha hydroxy acids became popular as a skin care agent in the 1990s they were considered by some to be a "wonder" skin care ingredient because of their multiple uses.

AHAs work by weakening the bonds between cells in the outer, dead layer of skin, therefore aiding in exfoliation and speeding up the normal skin-shedding process. By helping to remove this dull layer of dead skin cells and uncovering the new, healthy skin cells underneath, alpha hydroxy acids improve the texture of skin, unclog pores, reduce the appearance of fine lines and wrinkles and may aid in the building of collagen and elastin, both of which help to firm skin. In addition, alpha hydroxy acids may reduce the appearance of sun damage.

Many products combine other ingredients with AHAs to maximize their effectiveness. Beta hydroxy acids are synthetic acids generated from willow bark and birch, but are similar in structure to a naturally occurring acid in the skin, so they generally are non-irritating. When AHAs and BHAs are combined, the effectiveness of each is greatly increased, and each can be used in much lower concentrations. These milder concentrations mean that the products are less irritating to skin.

Often the skin incurs damage from free radicals, which are often caused by pollution, smoking or alcohol, causing the skin to look older than it really is. Free radicals bond with healthy skin cells and immediately begin destroying them, setting off a chain reaction of cell destruction. Antioxidants bond with free radicals and either prevent this chain reaction entirely or stop it once it has started. Products that combine AHAs and antioxidants help reduce the appearance of existing fine lines and wrinkles while protecting against future free radical skin damage.