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Glucosamine/Chondroitin for Joint Pain continued...

Chondroitin is believed to enhance the shock-absorbing properties of collagen and block enzymes that break down cartilage. Like glucosamine, this supplement is thought to help cartilage retain water, keep joints lubricated, and possibly reverse cartilage loss.

The research on these supplements is mixed. In a 2005 review of glucosamine, 20 studies involving 2,570 patients were analyzed -- showing glucosamine to be safe but not better than a placebo in reducing pain and stiffness and improving function. However, a World Health Organization review of evidence on glucosamine found that it relieves arthritis-related knee pain and improves joint function.

In 2006, the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), funded by the National Institutes of Health, found the two supplements were more effective when combined. However, only people with moderate or severe pain from knee arthritis reported significant benefit. They got better pain relief than from an anti-inflammatory painkiller.

In September 2008, a follow-up GAIT study compared people who took the supplements or medication for an additional 18 months. All those patients had moderate to severe osteoarthritis knee pain. After two years, there was no significant difference between the treatment and placebo groups.

There was a slight trend toward improvement among those with milder osteoarthritis of the knee who were taking glucosamine alone -- but not enough to draw definite conclusions, according to the lead researcher.

Robert Bonakdar, MD, director of pain management at Scripps Center for Integrative Medicine, takes issue with the NIH study, calling it "very flawed." The biggest problem, he tells WebMD, is that the study tested a relatively ineffective form of glucosamine.

Glucosamine hydrochloride is more readily available over the counter in the U.S., but glucosamine sulfate works better at relieving pain, says Bonakdar.

"All the European studies of glucosamine sulfate have shown it to be more effective than glucosamine hydrochloride," he tells WebMD. "The theory is that glucosamine sulfate is better absorbed, possibly because it is closer to the body's natural glucosamine." He advises his patients to take glucosamine sulfate.

He also advises taking glucosamine sulfate alone -- rather than with chondroitin -- because the two seem to work against each other, Bonakdar explains. "Chondroitin seems to prevent glucosamine from being absorbed."

Bottom line: Should you take glucosamine or chondroitin -- or not?

"With glucosamine and chondroitin sulfate, you're trying to repair cartilage," Plank explains. "But cartilage isn't always the issue, not always the reason for arthritis joint pain. These supplements are safe enough to try. Just give it two or three months -- you have to give it a chance. It's an option, and people who get relief swear by it."

The issue was further explored in a 2010 compilation of 10 studies, comparing glucosamine, chondroitin, or both on joint pain and X-ray findings in people with knee or hip pain. The researchers in this study did not find a benefit for either supplement when compared to placebo pills. Some experts are skeptical about how accurate their findings were, and still consider glucosamine to be a safe alternative to medications for arthritis, especially in people who are younger, not overweight, and with less severe arthritis.

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