Although hydroxy acids have received much attention in both the scientific and media communities, these naturally-occurring acids are heralded skin enhancers that have been used for thousands of years. Even the Queen of Egypt revered the use of hydroxy acids as a method for rejuvenating her famous skin. It has been said that the Queen of beauty regimes bathed nightly in sour milk (a common form of hydroxy acid), to improve the appearance of her skin.

More and more research is showing a clear link between the use of hydroxy acids as a method to reverse or prevent the effects of sun-based aging.

What are Alpha and Beta Hydroxy Acids?

Hydroxy acids are divided into two subgroups, alpha and beta. Alpha hydroxy acids (AHAs) are chemical compounds, both synthetic and natural, that are made up of a carboxylic acid that has been substituted with a hydroxy group on the adjacent carbon. In common parlance, they are exfoliants that come from natural substances such as the glycolic acid produced from sugar cane and lactic acid produced from milk.

AHAs are in many cosmetic products. They are known to help reduce the signs of aging, and their effectiveness in improving the look and feel of skin has been well-documented.

There is only one beta hydroxy acid (BHA) used in skin-care preparations, and that is called salicylic acid. This form of BHA is used in many "anti-wrinkle" creams and acne treatments.

The key difference between beta and alpha hydroxy acids is their lipid (oil) solubility. While beta hydroxy acids are lipid soluble, alpha hydroxy acids are only soluble in water. In this sense, beta hydroxy acid has the ability to penetrate a skin pore that holds old oils, sebum and dead skin cells. This is particularly valuable in the cases of oily skin, acne and blackheads. Alpha hydroxy acids work to soften skin that has been sun-damaged, loosened, and thickened by aging.

How They Work to Effectively Treat Wrinkles and Other Skin Concerns

In the form of a topical compound, AHAs have the ability to penetrate into the pores of the skin and act on our skin's living cells, helping it to produce more collagen and elastin. Collagen is responsible for giving skin a thick, pliable and wrinkle-free characteristic. Elastin is responsible for the amount of "bounce-back" and elasticity in the skin.

Beta hydroxy acid acts primarily as an exfoliant, causing the cells of the skin to become "unstuck." This process sloughs off dead skin cells, creating space for re-growth of new skin. It also loosens skin plugs, improving both the size and functional capacities of skin pores. Derived from the same ingredients in aspirin, beta hydroxy acid has powerful anti-inflammatory properties, reducing both swelling and redness in the skin. This acid also aids in accelerating the process in skin cell turnover and rejuvenation.

Studies show that both alpha and beta hydroxy acids can improve the appearance of wrinkling and uneven skin tones in photo-damaged skin within 6 months of consistent application.

Usage Recommendations and Possible Side Effects

Alpha hydroxy acids are normally quite safe as a topical cosmetic agent for the skin, particularly when used in the recommended dosage. Occasional common side-effects include mild irritation, redness and flaking of the skin. If the concentration of the pH level is within a range of 3.5-4 and the concentration of AHA is 10% or less, there should be less chance for irritation.

Chemical peels, which have a much higher concentration of acids, are usually responsible for the more harmful side-effects. This may include mild forms of redness, blistering, burning and skin discoloration, which go away within a short time period. Dermatologists recommend wearing sunscreen with UVA and UVB protection when using either form of alpha hydroxy acids, as both increase sun sensitivity. Symptoms may include burning, redness, burning, itching, and scarring.

The use of beta hydroxy acid can create even greater sun sensitivity. Studies show that, especially in lighter-pigmented skin, a 50% increase in sensitivity may occur, with the same side effects as with AHA. Beta hydroxy acid works best in a concentration of 1% to 2% and at a pH of 3 to 4.

Source:

BKempers, S. et al., "An evaluation of the effect of an alpha hydroxy acid-blend skin cream in the cosmetic improvement of symptoms of moderate to severe xerosis, epidermolytic hyperkeratosis, and ichthyosis," Cutis, June, 1998; 61(6):347-50

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