Alpha-hydroxy acids, or AHAs, are commonly used in cosmetics such as chemical peels to rejuvenate sun-damaged skin. They also have other therapeutic effects. For instance, AHA agents can help to remodel the epidermis and speed up the turnover or shedding of outmost skin cell layers, according to a study published in the "Journal of Dermatology" in 2006.
Identification
Alpha-hydroxy acids are chemical compounds found in milk, fruits and sugar cane. However, AHAs may be natural or synthetic, states CosmeticsInfo.org. The two AHAs you're most likely to find in beauty products are lactic acid--which is similar to the acid you burn when exercising--and glycolic acid, which comes from sugar cane, according to CosmeticsInfo.org.
Function
In cosmetic products, alpha-hydroxy acids are used as humectants and exfoliants. By removing old skin cells, they clear up dull complexion and improve skin tone. They're particularly useful in treating oily skin. According to Dermatologica, a website of the International Dermal Institute, oiliness slows desquamation, which is your body's natural process of shedding old and dry skin cells to allow new ones to grow.
AHA versus BHA
Beta-hydroxy acids, or BHAs, are another group of acids found in cosmetics of which the most common is salicylic acid. Similar to alpha-hydroxy acids, BHAs are also effective exfoliants as they unglue dead skin cells. Beta-hydroxy acids are soluble in oil and alpha-hydroxy acids are water-soluble, states Paula Begoun, author of "The Original Beauty Bible." AHAs are more effective for sun-damaged or photo-aged skin, and BHAs should be your choice for tackling blackheads and blemishes.
Concentration and pH
Cosmetic products contain different concentrations of alpha-hydroxy acids at different pH levels. The pH of a substance tells you how acidic or alkaline it is. As Begoun explains, the lower the AHA is on the scale, the more effective it will be in treating your skin. Products with AHAs at 5 to 10 percent with a pH of 3 or 4 are the best. If a product you choose doesn't indicate the concentration or pH, check to see if it is listed in second or third spot on the list of ingredients. This signals that it likely has an AHA concentration of 5 percent or more, notes Begoun.
Caution
According to the U.S. Food and Drug Administration, alpha-hydroxy acids in cosmetics are safe to use if the final product has a pH of 3.5 or more and the AHA concentration is10 percent or less. However, these products increase your skin's sensitivity to the sun. Some alpha-hydroxy acid cosmetics contain sunscreen and indicate that on the label. If not, always apply sunscreen separately.
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