Hyaluronic acid (also called hyaluronan or hyaluronate or HA) is a linear polysaccharide with repeating disaccharide units composed of D-glucuronic acid and N-acetyl glucosamine. HA is distributed widely throughout connective, epithelial, and neural tissues. HA is continually produced by hyaluronan synthases, and degraded naturally by a category of enzymes called hyaluronidases. A 70kg person has approximately 15 grams of HA throughout his or her body, one- third of which is degraded and synthesized every day.

HA is one of the main lubricating components of synovial joint fluid, and it has been shown to increase the viscosity of the fluid. HA is also an important component of cartilage, where is forms complexes that absorb water and help the cartilage maintain resiliency. Age leads to a decrease in the molecular weight of HA in cartilage. HA-based products developed for osteoarthritis (called “viscosupplementation”) aid in pain relief, as well as lubrication and cushioning of the joint.

Especially skin contains large amount of hyaluronic acid which amounts to about 1/3 of total hyaluronic acid existing in a live body. In the skin, HA has the ability to absorb large quantities of water – 500-1,000 times its weight - and to form complexes with collagen and elastin. These complexes support the structure of the skin, contribute to the skin’s elasticity, and create volume in the skin to diminish the appearance of wrinkles and fine lines. Age, as well as exposure to the sun and pollution, leads to decreased production of HA, resulting in decreased volume and the appearance of wrinkles.