Key arthritis supplements have no effect find scientists

Glucosamine and chondroitin are given out on NHS prescription or bought over the counter by patients to alleviate symptoms of osteoarthritis.

This is the most common type of arthritis in the UK and mostly occurs in the knees and hips.

About 8.5 million Britons are thought to suffer from the condition, which can cause crippling pain.

Today, experts writing online in the British Medical Journal said their review of existing research concluded the supplements are not effective.

They examined ten existing studies and found no evidence of improvement when supplements were taken alone or in combination.

More than 3,800 patients suffering from osteoarthritis in their hips, knees or both joints took part in the studies.

Patients were typically aged 58 to 66 and had suffered symptoms for between six months and ten years.

The results showed the supplements had no effect on joint pain or on the degree of narrowing between joints. Narrowing joint space indicates cartilage loss and worsening osteoarthritis. But the authors, led by Professor Peter Juni at the University of Bern in Switzerland, said some patients did think the supplements helped them.

This may be due to factors such as the natural course of arthritis, or patients simply believing the supplements work.

"We are confident that neither of the preparations is dangerous," the authors said. "Therefore, we see no harm in having patients continue these preparations as long as they perceive a benefit and cover the costs of treatment themselves.

"Coverage of costs by health authorities or insurers for these preparations and novel prescriptions to patients who have not received other treatments should be discouraged."

Both glucosamine and chondroitin are available on the NHS. Many more doses are bought over the counter.

Global sales of glucosamine supplements reached almost 1.3 billion in 2008 - around a 60 per cent increase compared with 2003, the study said.

Osteoarthritis causes damage to cartilage, which is essential to allow joints to move easily and without friction.The condition can cause bony growths around the edge of the joints and inflammation of surrounding tissues.

Jo Cumming, helplines manager at Arthritis Care, said the charity would support more research in this area.

Jane Tadman, from Arthritis Research UK, said: "Glucosamine and chondroitin are two of the most popular supplements for osteoarthritis and two of the most commonly investigated.

"Many trials have been done but with very mixed results."

Carrie Ruxton, of the Health Supplements Information Service (HSIS), which is funded by the industry, said: "Given the wealth of anecdotal evidence available, we know many people gain benefit from taking glucosamine and chondroitin for the maintenance of joint health and are willing to continue regardless some clinical trials."