Hyaluronic Acid or HA (not to be confused with AHA) is one of the most important, if not the most important, macromolecules of the human body, and is absolutely vital to the creation and maintenance of healthy skin. HA is a very large polymeric carbohydrate found in the extra cellular matrix (ECM) surrounding our skin cells and is able to bind thousands of times its molecular weight in water; in essence it is our skin's natural water retention complex, without it our skin would shrivel up like a raisin. HA provides the vehicle that cells move through and is therefore vital to tissue differentiation and wound healing. Our skin is an HA metabolic factory: it is always making HA, breaking it down, and recycling it. In fact, in about a four day period, we replace all of the HA in our skin. The natural trigger for the synthesis of HA by our skin is lactic acid. Lactic acid stimulates HA deposition in the skin at the greatest rate compared to all other AHAs, producing new HA in a natural way that makes your skin look healthy and radiant.