There is growing evidence that two supplements — glucosamine and chondroitin sulfate — alone or in combination provide symptomatic relief for osteoarthritis with few side-effects, but most doctors still take a cautious approach in recommending these drugs and monitoring patients who use them.Treatment for osteoarthritis mainly offers relief of symptoms; only joint replacement is curative. Doctors prescribe drugs like Vioxx and Celebrex, called nonsteroidal anti-inflammatory drugs (NSAIDs), to ease osteoarthritis pain in patients with mild to moderate symptoms. Other options, such as injections of hyaluronic acid agents into the knee, are used to preserve what’s left of the joint space and delay knee replacement surgery.
None of these therapies really do anything to address the continued degeneration of the joint tissues. However, some experts are hopeful that future studies of glucosamine and chondroitin sulfate will show that these agents actually do stop the breakdown of joint tissue.
Studies on glucosamine and chondroitin sulfate began appearing in the 1980’s, but most were conducted in Europe and Asia, and many were anecdotal reports. The theory behind the use of these supplements was to deliver substances extracted from cartilage into the body to facilitate cartilage repair.
Glucosamine and chondroitin sulfate were believed to stimulate the production of proteoglycan, a fundamental component of cartilage. These chemicals are present in the body naturally, and in their natural form they prelude the development of proteoglycan.
Other proposed theories suggest glucosamine and chondroitin sulfate may have mild anti-inflammatory properties. Experts also believe they may increase concentrations of protective substances in the cushion around the knee called the synovial fluid, which acts as a lubricant and shock absorber for the joint.
Research has shown that oral glucosamine is rapidly absorbed by the body and a small amount is taken up into the tissues and secreted into the lining of the joint, called the synovium. In contrast, oral chondroitin sulfate is poorly absorbed and even less is retained in the tissues, making its suggested method of action more controversial.
Glucosamine is well-tolerated by patients and causes few side-effects such as nausea, heartburn and diarrhea. In general it is better tolerated than the NSAIDs, and has no known food or drug interactions. However one report did raise concern for diabetics, since glucosamine has been shown to raise insulin resistance.
Although the safety of chondroitin sulfate has not been assessed in long-term studies, reports show it is well-tolerated and has no known food or drug interactions.
The benefit of these two supplements is that they provide symptomatic relief in patients with mild to moderate osteoarthritis. Their ability to modify disease progression has not been fully proven in clinical trials.
A meta-analysis of several studies on glucosamine and chondroitin sulfate published in the Archives of Internal Medicine this summer concluded that both provide relief of osteoarthritis symptoms, but that further studies need to look at their disease-modifying characteristics.
The National Institutes of Health are currently conducting a trial comparing the efficacy of the combination of the two supplements to each supplement alone versus a placebo in reducing osteoarthritis pain. Their goal with the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT) is to "definitively determine the efficacy of these agents." They also hope to determine the long-term benefits, if any, as well as the side-effects of taking glucosamine and chondroitin sulfate.
Patients considering these supplements should consult their doctor, because unlike prescription and over the counter drugs, the Food and Drug Administration does not regulate food supplements. The actual quality and content of glucosamine and chondroitin sulfate can vary from nearly zero to the dosage as labeled on the bottle or more. And as with any medication, if patients experience side-effects they should inform they doctor right away.
