Glucosamine and chondroitin have no effect on arthritis, according to researchers.
Patients can buy the supplements over the counter or are prescribed them by their doctors to ease the symptoms of osteoarthritis - the most common type of arthritis.
But experts concluded that the supplements were ineffective, either when taken alone or in combination, after analysing 10 existing studies.
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 10 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.
However, the authors, led by Professor Peter Juni at the University of Bern in Switzerland, said some patients did think the supplements helped them.
Both glucosamine and chondroitin are available on the NHS, with 907,400 prescriptions issued in England in 2009. Many more doses of the supplements are bought over the counter by patients.
This is despite guidance from the National Institute for Health and Clinical Excellence (NICE) saying neither supplement is backed by clinical evidence.
The findings have been published in the British Medical Journal.
Copyright © Press Association 2010
British Medical Journal
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