Glucosamine and chondroitin, << gloo kohs uh MEEN, kon DROY tihn >> , are substances produced by cells in and near the cartilage. Cartilage is the smooth tissue that cushions bones against shock and prevents them from rubbing against each other. Glucosamine and chondroitin are also combined in capsules, tablets, powders, or liquids and sold as a dietary supplement. The substances are also added to some skin creams. In the United States, glucosamine and chondroitin rank as the most widely used dietary supplement intended to provide relief from the condition osteoarthritis. Osteoarthritis occurs when the smooth cartilage of a joint wears out. It causes pain, swelling, and a reduction of motion in the affected joint (see Arthritis ).
Most glucosamine supplements contain a compound of glucosamine hydrochloride or glucosamine sulfate. Such compounds are extracted from shellfish or made from vegetable sources. Many people believe that the supplements help rebuild and repair cartilage damaged by osteoarthritis. Chondroitin sulfate is obtained from animal cartilage. Many people believe it helps to increase the elasticity of cartilage and prevent cartilage breakdown. The two substances are often combined to treat joint pain in people. Dietary supplements of glucosamine and chondroitin are also widely sold for the treatment of joint pain in dogs, cats, and horses.
Medical experts have conducted many research studies on glucosamine and chondroitin. They have tried to find out whether the substances, given either separately or together, benefit patients with osteoarthritis. However, research studies have produced unclear results. For example, a study by the United States National Institutes of Health (NIH) suggested that some glucosamine and chondroitin supplements may provide limited relief of moderate-to-severe knee pain in adults with osteoarthritis. In patients with mild pain, however, the supplements showed no benefit.
Medical experts warn that such dietary supplements as glucosamine and chondroitin must be selected carefully. They recommend that people consult a physician or a registered dietitian before taking any supplement.
