Two popular supplements taken by millions of people around the world to combat joint pain do not work, new research has indicated.

The supplements, glucosamine and chondroitin, are taken either on their own or in combination to reduce the pain caused by osteoarthritis in hips and knees. 

However the researchers, led by Prof Peter Jüni at the University of Bern in Switzerland, said that these supplements are not dangerous.

“We see no harm in having patients continue these preparations as long as they perceive a benefit and cover the cost of treatment themselves,” they said.

But they added that health authorities and health insurers should not cover the costs for these preparations, and new prescriptions to patients who have not received treatment should be discouraged.

Osteoarthritis of the hip or knee is a chronic condition, which is mainly treated with painkillers and anti-inflammatory drugs but these can cause stomach and heart problems, especially if used long-term.

In the past decade, GPs and rheumatologists have increasingly prescribed glucosamine and chondroitin to their patients. And many individuals around the world have purchased them over the counter.

In 2008, global sales of glucosamine supplements reached almost $2 billion, which represents an increase of about 60% since 2003.

Prof Jüni and colleagues analysed the results of 10 published trials involving 3,803 patients with knee or hip osteoarthritis. They assessed changes in levels of pain after patients took glucosamine, chondroitin, or their combination, with placebo or head-to-head.

They discovered no clinically relevant effect of chondroitin, glucosamine, or their combination on perceived joint pain or on joint space narrowing.

Despite this finding, some patients are convinced that these preparations are beneficial, said the study authors. They suggest this might be because of the natural course of osteoarthritis or the placebo effect.

“Compared with placebo, glucosamine, chondroitin, and their combination do not reduce joint pain or have an impact on narrowing of joint space.

“Health authorities and health insurers should be discouraged from funding glucosamine and chondroitin treatment,” they concluded.

The research was published online by the BMJ.