Two popular supplements taken by millions of people around the world to combat joint pain, glucosamine and chondroitin, do not work, according to research published today - but they don't hurt you either.  Basically, they are expensive placebos.

Glucosamine and chondroitin are either taken on their own or in combination to reduce the pain caused by osteoarthritis in hips and knees.  The researchers, led by Professor Peter Jüni at the University of Bern in Switzerland, state that although they don't work 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."

However, they note, "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."   So buy them if you are convinced they work, but don't ask insurance to cover it.

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. Treatments that not only reduce pain but slow the progression of the disease would be desirable, say the authors.

In the last decade, general practitioners and rheumatologists have increasingly prescribed glucosamine and chondroitin to their patients and many have also purchased them over the counter. In 2008 global sales of glucosamine supplements reached almost $2 billion, an increase of about 60% since 2003.   But studies related to the benefit of that $2 billion spent on glucosamine and chondroitin were conflicting so a large scale review of studies was needed to determine whether or not the supplements actually work.

Professor Jüni and colleagues analyzed 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.  

Result: No clinically relevant effect of chondroitin, glucosamine, or their combination on perceived joint pain or on joint space narrowing.  Despite that, some patients are convinced that these preparations are beneficial, say the authors, and they suggest this might be instead because of the natural course of osteoarthritis or the well-discussed 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 conclude.

Citation: Simon Wandel, Peter Jüni, Britta Tendal,Eveline Nüesch, Peter M Villiger, Nicky J Welton,  Stephan Reichenbach, Sven Trelle, 'Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis', BMJ 2010; 341:c4675 doi: 10.1136/bmj.c4675