Hyaluronic acid CasNo.: 9004-61-9 supplements are made using synthesized forms of a compound that naturally occurs in the body. Classified as a polysaccharide (a type of carbohydrate), hyaluronic acid occurs in high concentrations in the skin, joints, and eyes, where it provides lubrication and sustains tissue hydration. Since hyaluronic acid levels decrease as you get older, hyaluronic acid supplements may help treat or prevent aging-related health conditions.