ALPHA-HYDROXY ACIDS
WHAT ARE THEY? Deriving from fruit and sugar acids, the five main types of alpha-hydroxy acid (AHA) used in skincare products are: glycolic acid from sugar cane, which accelerates the skin's exfoliating process; lactic acid from milk (a tried and true skin softener and moisturiser - even Cleopatra bathed in sour milk); citric acid from oranges and lemons; tartaric acid from grapes; and malic acid from apples and pears. The last three are said to brighten and even out skin tone.
HOW DO THEY WORK? They exfoliate the skin chemically (as opposed to mechanically with granular scrubs and wash cloths) by sloughing off old epidermal cells and skin debris such as stale oil. This stimulates and accelerates new skin-cell production - faster cell turnover means a fresher appearance. They also help to remove excess oil while encouraging a natural moisture balance.
CHOOSING AND USING AHAs The ideal AHA concentration in a skincare product is five to eight per cent - anything above 10 per cent and you're into chemical peels, which are much harsher and should only be performed by doctors or certified skincare professionals. If the concentration isn't provided - and beauty companies aren't required by law to give it - choose another brand, contact the company or read the label. As a guide, if the AHA is the second or third ingredient listed, the product is likely to contain the correct concentration. To avoid irritation, use only one product that contains AHAs. Moisturisers are the best because the AHA needs to be absorbed into the skin to work; cleansers are washed off before this can happen. Always proceed with caution, particularly if your skin is sensitive: start with a low concen-tration and do a patch test first. The AHA content will make the skin tingle but it shouldn't burn. Use the product once every other day and build up to the recommended frequency. Stop using it immediately at the first sign of any adverse reaction. Side effects include skin becoming itchy and sore for a prolonged period, flakiness, the appearance of red scaly patches and more spots than usual.
THE CATCH Ironically, while AHAs are said to lessen the effects of sun damage, their use is said to increase the skin's sensitivity to UV rays by up to 50 per cent. If going out, wait for about 10 minutes for the AHAs to be absorbed, then apply sunscreen with a minimum protection factor of 15.
ARE AHAs THE SAME AS BHAs? No. AHAs are water-soluble and BHAs (beta-hydroxy acids) are fat-soluble. This means they can penetrate the skin's pores and clear out dead cells from within. BHAs are said to be less harsh than AHAs and better for oily skin; use AHAs on tougher, sun-damaged skin that is not prone to spots.
WHAT DO AHAs DO? With proper, continued use, they can reduce fine lines and age spots and improve the skin's texture and tone.