AHAs (Alpha Hydroxy Acids or α-hydroxy acids) are a class of cosmetic ingredients that occur naturally as acid components of many botanical substances like fruits (hence their name), sugar cane, milk or honey. They are part of the category of "chemical exfoliants".
Chemical exfoliants work by dissolving the keratin that binds skin cells, which allows the cells to be shed from the skin. Using a chemical exfoliant might sound very harsh, but they can actually be quite effective and gentle (coffee grounds, for example, salt or sugar are much more aggressive to your skin).
Glycolic acid, malic acid, lactic acid, gluconic acid or tartaric acid are all natural acids found in many cosmetic products. They can have a very basic function, like PH adjustment, or can be added to skincare products for more refined purposes like the chemical exfoliation that results in a more even skin.
The cosmetic uses of AHAs date back to the times of Cleopatra, when the use of milk (remember reading about her milk baths?) was known for helping to have smoother, beautifully looking skin. Because lactic acid, found in milk, is also naturally found in the skin, it isn't likely to cause allergic reactions.
AHAs improve skin elasticity, hydration and texture, reduce discoloration and unclog pores. Improvements in skin texture and tone are the result of an increase in skin cells production, which outpaces the rate of melanin production, resulting in a more even skin.
A very good way for your skin to benefit from fruit acids are fresh exfoliant masks, which can be done with very common and easy to find ingredients: yogurt, honey (my favorite!), kiwi or banana purée will leave your skin glowing, as are packed with vitamins, minerals and acids. The cool thing about these, and the vitamins and minerals they contain, is that everything is water soluble. That means the ingredients are dissolved in water, and are, therefore, absorbed by your skin.
I always recommend to start simple, with only one or two ingredients and to observe any improvements or effects (or reactions, that can also happen) in your skin.
The instructions are very simple: apply the food of your choice on clean skin, let it sit for 15-20 minutes (while hearing your favorite podcast or music) and wash it again. Finish with your moisturiser and you’re ready for your beauty sleep!
P.S. Repeat every week.