Hyaluronic acid forms the backbone of other proteoglycans and is responsible for the high viscosity of synovial fluid and its lubricating and shock-absorbing properties. As well, synovial fluid provides nutrition for the joint cartilage. The proteoglycan that is depleted more than others is hyaluronic acid. Osteoarthritis worsens with age. Its frequency rapidly increases beyond age 55, and by age 75 about 85 percent of individuals have evidence of osteoarthritis.
Women tend to suffer more often from osteoarthritis in their hands and knees and men in their hips.
A Therapeutic Agent Glucosamine sulfate, a constituent of cartilage, is a small molecule that is easily absorbed into the blood and joints when taken as a supplement. In vitro studies using cells in culture show that glucosamine stimulates GAG production. 3 Glucosamine sulfate has been shown to decrease pain and improve joint function in osteoarthritis patients. Although its exact mechanism for improving osteoarthritis symptoms is not known, experiments suggest glucosamine may stimulate cartilage matrix formation, reduce enzymatic digestion of cartilage components and provide an anti-inflammatory effect. An alternative or, perhaps, additional explanation is that glucosamine stimulates the production of hyaluronic acid in joint synovial fluid.