Two popular supplements used to treat joint pain don't work and health authorities should stop paying for them, a new study says.

European researchers analyzed the results of 10 past trials in 3,803 patients who took glucosamine, chondroitin or a placebo to treat arthritis in their hips or knees. They found neither supplement, taken either separately or together, did any better than a placebo.

The study was led by Peter Juni, head of the Institute of Social and Preventive Medicine at the University of Bern in Switzerland. It was paid for by the Swiss National Science Foundation and was published Friday in the journal BMJ.

For the past decade, glucosamine and chondroitin have been recommended by doctors to treat arthritis in the hip or knee. The supplements are components of human connective tissues found in cartilage and bone. Globally, sales of glucosamine supplements hit nearly $2 billion in 2008.

Chronic arthritis in the hip or knee can be treated with drugs that reduce inflammation, but those can cause serious stomach and heart side effects if they are used in the long term.

In the BMJ analysis, the researchers didn't find any proof glucosamine or chondroitin were dangerous. "We see no harm in having patients continue (taking these supplements) as long as they perceive a benefit and cover the cost of treatment themselves," wrote Juni and colleagues.

Still, the researchers said because the supplements didn't reduce joint pain, insurers and governments should stop buying them. "New prescriptions to patients who have not received treatment should be discouraged," they wrote.

In Britain, the government does not pay for the supplements, citing a lack of evidence.

Jane Tadman, a spokeswoman for the charity Arthritis Research U.K., said results from previous trials testing the supplements had been mixed. She was not connected to the research and said it was up to patients to decide whether to keep taking the supplements.

"Some people may want to consider an over-the-counter trial as part of a wider self-management plan which includes exercise and keeping to an ideal weight," she suggested.