After two years, there were no substantial differences between those people taking vitamin D and those taking placebo, the researchers found.
"This study tested whether vitamin D supplementation, given over a two-year period, could influence the rate of progression of joint damage in people with knee osteoarthritis," McAlindon said in a statement. "The study found no difference compared to a placebo treatment."
Osteoarthritis is the most common joint disease affecting middle-age and older people. The condition causes progressive damage to the joint cartilage and causes changes in the structures around the joint, the researchers said.
These changes can include accumulation of fluid, bony overgrowth, and loosening and weakness of muscles and tendons, all of which can limit movement and cause pain and swelling.
Dalal noted that the only treatment for osteoarthritis is physical therapy, exercise and anti-inflammatory medication. Eventually, many people suffering from knee osteoarthritis will need a joint replacement, he said.
Research suggests that other treatments such as glucosamine and other herbal remedies also don't work, Dalal said. "But some people are desperate and try alternatives," he said.
For more information on osteoarthritis, visit the U.S. National Library of Medicine.
SOURCES: Kevin Dalal, M.D., assistant professor, rehabilitation medicine, University of Miami Miller School of Medicine; Nov. 7, 2010, presentation, American College of Rheumatology annual meeting, Atlanta
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