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How effective are nutritional supplements in relieving pain from osteoarthritis?
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Arthritis sufferers react with enthusiasm to any treatment promising relief for the pain and stiffness that tortures their joints. The introduction of nutritional supplements such as glucosamine with chondroitin has raised such hopes, but how effective these supplements are is still up for debate. More than 40 million Americans suffer from osteoarthritis (OA), commonly thought of as a wear and tear disease that becomes increasingly common with aging. By the age of 65, an estimated 85% of the population have some degree of OA. Treatment usually focuses on relieving pain and stiffness in joints with acetaminophen or non-steroidal anti-inflammatory drugs (NSAIDS) such as aspirin and ibuprofen. NSAIDS pose significant risk of stomach ulcers and bleeding, however, and many people find it difficult to control the symptoms of OA. At least half of patients say they are not helped by pain medications. ACR Guidelines The American College of Rheumatology recommends acetaminophen as a first-line treatment of osteoarthritis, with NSAIDS added as needed. The COX-2 inhibitor, celecoxib (Celebrex) has added options since it relieves pain but does so without causing the same level of gastric bleeding and ulceration. Injections of hylauronic acid (HA) into affected joints can bring relief for some patients. Hylauronic acid is a component of the synovial and cartilage tissues. An injection of the acid into a joint can help it stay lubricated and increase elasticity. In one study the beneficial effects lasted six months or more. The final option for patients who no longer find relief from pain medications and other medical treatments is joint replacement surgery. Hip and knee replacements are common procedures, especially in the elderly, and results are very positive with most patients reporting a greatly improved quality of life. Nutritional supplements have gotten increased attention in the last several years. Glucosamine with Chondroitin Normal articular cartilage is composed of chondrocytes that occupy approximately 5% of the tissue volume, and the extracellular matrix, which composes the remaining 95% of the tissue. The chondrocytes secrete and maintain the matrix; the matrix in turn supplies the chondrocytes with an environment conducive to their continued existence in the face of a high level of mechanical stress. Because of its role in chondrocyte support, and because it physically forms such a large percentage of cartilage, the importance of the matrix in joint function cannot be overstated. Water comprises approximately 70% of the matrix. The remainder of the matrix consists of primarily collagen and proteoglycans. Proteoglycans are composed of glycosaminoglycans attached to a linear core protein. Proteoglycans are important in many body tissues. The proteoglycans that are specific to cartilage contain the glycosaminoglycans chondroitin sulfate-4, chondroitin sulfate-6, and keratan sulfate. The importance of the matrix is evident in the pathogenesis of OA, which results when the cartilage matrix fails. In About 5% of cases, OA affects individuals having some predisposing condition, such as a traumatic injury to a joint. These cases are referred to as secondary OA. In the majority of cases OA appears to be part of the aging process and without apparent initiating cause. The conventional therapies to treat OA are largely palliative and focus on the reduction of pain and suppression of inflammation via surgery, changes in lifestyle, and pharmaceutical approaches. Research, focusing on slowing the progression of OA and promoting cartilage matrix synthesis, has identified substances, termed chondroprotective agents, which counter arthritic degenerative processes and encourage normalization of the synovial fluid and cartilage matrix. HA is a glycosaminoglycan found in synovial and cartilage tissues. However, HA cannot be taken orally and must be injected directly into the joints. Because it is injected directly into the joint, its onset of action is rapid. Conversely, its route of administration does limit its therapeutic applications to some degree, and high cost is also a factor. Glucosamine functions in the body as a precursor in glycosaminoglycans. Supplying exogenous glucosamine provides the body with additional raw materials for matrix production. Since OA results when cartilage breakdown exceeds the chondrocytes synthetic ability, providing exogenous glucosamine increases matrix production and seems likely to alter the natural history of OA. Glucosamine also has a mild anti-inflammatory activity. Chondroitin is the most abundant glycosaminoglycan in articular cartilage. It is a natural component of several tissues in the body in addition to cartilage, including tendons, bone, intervertebral disk, the cornea, and heart valve. As a chondroprotective agent, chondroitin helps to inhibit many of the degradative enzymes that break down the cartilage matrix and synovial fluid in OA. Because glucosamine induces increased synthesis of matrix compounds, and chondroitin sulfate inhibits breakdown, their concurrent use results in a net increase in the amount of normal cartilage matrix, thus slowing the progression of OA as well as reducing the symptoms of the disease. Research on the effectiveness of glucosamine and chondroitin is ongoing. Studies to date are inconclusive, with some showing moderate to large effects in relieving symptoms of arthritis, while other studies conclude these supplements may be no more effective than placebo. The negative results may be due to the fact that the study group was relatively old (an average of 63), was overweight and suffered from fairly severe arthritis. Earlier detection and treatment of OA with these supplements may therefore show to be more beneficial, however all the research is not in yet. Glucosamine and chondroitin sulfate are both obtained from animal tissue sources (such as the shells from crabs and shrimp), and purity can vary widely depending on extraction techniques and anlysis technology. The purity of the compounds used can certainly be expected to affect efficacy. Furthermore, it is important to point out that glucosamine and chondroitin sulfate are considered dietary supplements, and are therefore not regulated by the Food and Drug Administration. Purchasers of dietary supplements should be careful to buy from a reputable manufacturer that uses quality-control programs to validate raw material and finished product purity. Hope for new and better drugs to treat osteoarthritis in the future is bolstered by continued research efforts that are now focusing not just on the role of cartilage but on the whole joint. For many researchers cartilage destruction is just one part of a complex puzzle.
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