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The popular supplement glucosamine, used by many arthritis sufferers, was found to be no better than placebo pills for relieving the pain of hip osteoarthritis or increasing the ability to do everyday activities, according to a new study from the Netherlands.
"In our study, there was not much room for doubt," says Rianne Rozendaal, MSc, the study's lead researcher.
"The differences between the glucosamine and placebo group were all very small," says Rozendaal, a researcher at the Erasmus Medical Center in?Rotterdam, Netherlands.
But representatives of the supplement industry disagree, with one manufacturer saying the researchers may have focused on people too early in the arthritic process.
An estimated 21 million Americans have osteoarthritis (or "wear-and-tear" arthritis) affecting the hips, knees, and other joints, according to the Arthritis Foundation. The condition is marked by the breakdown of the joint's cartilage, which cushions the bone endings and allows you to move easily.
A substance found naturally in healthy joint cartilage, glucosamine stimulates the formation and repair of cartilage, according to the American Academy of Orthopaedic Surgeons, but over-the-counter supplements come from animal or plant sources. Studies of the effectiveness of glucosamine have yielded mixed findings.
Rozendaal and her team assigned 222 patients, all with hip osteoarthritis that was generally termed mild, to take either 1,500 milligrams of glucosamine sulfate or a placebo pill every day for two years. On average, patients were in their early 60s.
About equal numbers in each group underwent total hip replacement surgery during the study. The researchers evaluated the patients at three, 12, and 24 months after they began the treatments, collecting information about the patients' pain levels and how well they could perform everyday activities.
X-rays were taken to measure the joint space in the hip. As osteoarthritis gets worse, this joint space gets narrower.
At the study's end, the pain scores of those who took the supplement didn't differ much from those who took the placebo, Rozendaal says. On the scale used, "the pain scores range from 0 to 100," she explains in an email interview, "where 0 equals no pain and 100 equals most severe pain."
The average difference between groups in pain scores was a decline of just 1.5 points, she says. To be statistically significant, there would have to have been a difference of at least 10 points, she says.
"Our trial does not suggest an effect of glucosamine for hip osteoarthritis," she adds.
No differences were found between groups in the joint space narrowing, either, Rozendaal says. The study is published in the Annals of Internal Medicine.