Hyaluronic acid is a natural structural component of our skin and is present in connective tissue throughout the human body.  Its main purpose is to protect cell structure by acting as a "water cushion" between skin cells.  As our skin ages and is subjected to external environmental changes, our natural levels of hyaluronic acid are reduced.  There is some limited evidence that topical applications of HA is absorbed through the skin and "feeds" our existing cells. Formulators also find this additive helpful in topical creams designed to minimize scar tissue.