Hyaluronic acid, also known as hyaluronan, is a clear, gooey substance that is naturally produced by your body. The largest amounts of it are found in your skin, connective tissue and eyes. Its main function is to retain water to keep your tissues well lubricated and moist. The skin contains about half of the HA in the body; it binds to water molecules, which helps keep the skin hydrated and supple. Hyaluronic acid works by acting as a cushion and lubricant in the joints and other tissues. In addition, it might affect the way the body responds to injury. The HA within our bodies holds a thousand times its weight in water to not only retain all that moisture in our skin and joints, but also prevent all that moisture from evaporating into the air. The body's ability to produce hyaluronic acid declines with age