Alpha hydroxy acids are best known for their skin-care powers -- apply products with this ingredient to smooth fine lines and surface wrinkles, improve skin's texture, cleanse pores and enhance your overall look. AHAs, as they're commonly known, may be applied topically, but they come from natural sources. AHAs are a collection of acids, including lactic, citric and malic acid; many familiar foods contain them.
Lemon, grapefruit and other citrus fruits contain alpha hydroxy acids, primarily in the form of citric acid. In skin products, citric acid works as an astringent, a preservative and as an ingredient to balance the acid-alkali ratio. Lemon juice has a long history of being applied to the face to help fade freckles and skin discoloration. Be aware that citric acid, especially lemon juice, applied to the skin increases your sun sensitivity. If you eat more citrus fruits, you'll also load up on vitamin C, which helps boost your skin's appearance from the inside out.
Lactic acid is prevalent in soured milk and yogurt. Apply full-fat plain yogurt to your skin as a natural mask. For a food to help bolster healthy skin, whip yogurt up into a smoothie with antioxidant-rich blueberries, strawberries and raspberries.
Malic acid comes from apples -- both the whole fruit and cider. Use the acid as an astringent to help stimulate cell renewal. Applied to the face, it will make your skin feel smooth and tight.
Mandelic acid is used in skin peels that help even out skin tone and repair sun damage. People who have acne scarring may also benefit from use of mandelic acid. Derived from bitter almonds, it undergoes a chemical process before being used as an ingredient in skin care products.
Other Good Skin Foods
Papaya and pineapple don't contain alpha hydroxy acids, but they do contain papain and bromelain, enzymes that work in much the same way. These enzymes stimulate you to exfoliate a layer of dead skin cells and result in a softer, smoother appearance. Apply straight pineapple juice to your face, or rub your face with the inner peel of the papaya to benefit.