A new research published in the journal Arthritis and Rheumatism shows that glucosamine and chondroitin, two dietary supplements prescribed for people suffering osteoarthritis, are no better that placebo in slowing the cartilage loss in the knees.

The large study led by University of Utah doctors is a follow-up to a 2006 study that compared the benefits of dietary supplements with those of sugar pills or the arthritis pain medication Celebrex in relieving pain in osteoarthritis sufferers. The original study, funded by the National Institutes of Health, found no pain relief benefit over placebo, except in a subset of subjects with moderate to severe osteoarthritis knee pain; these patients got a significant pain relief with a combination of the two supplements.

For the second study, researchers continued to give patients the popular supplements, sugar pills or Celebrex and measured whether the space between their knee joints decreased. The study, which followed 572 volunteers for another 18 months after the first study, found the supplements did not appear to slow the loss of cartilage, taken either alone or together. The results were better only for a smaller subgroup of participants with moderate-to-severe pain. For them, the combination of glucosamine/chondroitin showed some pain relief. The researchers performed X-rays of the ailing joint at the beginning and at the end of the trial. The X-rays showed no differences in the treatment groups.

Dr. Allen Sawitzke of the University of Utah School of Medicine, who helped lead the study and colleagues said some of their findings were confusing and added that more study was needed. The researchers said that more patients and a better method for measuring the distance between the bones would have helped. Scientists say they had trouble interpreting their results because the damage occurred much more slower than they had expected. Dr. Allen D. Sawitzke said he would neither encourage nor discourage patients from taking the supplements.

According to the U.S. Centers for Disease Control and Prevention, about 20 percent of all Americans have been diagnosed with arthritis. Osteoarthritis is the most common form of arthritis; it commonly affects the hips, feet, spine, and the large weight bearing joints, such as the hips and knees. As OA progresses, the affected joints appear larger, are stiff and painful, and usually feel worse, the more they are used throughout the day. As the bone surfaces become less well protected by cartilage, the patient experiences pain upon weight bearing, including walking and standing. About 21 million Americans suffer from pain and stiffness of osteoarthritis, according to the most recent figures. Osteoarthritis is the result of several factors including age, genetics, weight, joint injuries and gender.

A previous study conducted by researchers at the Erasmus Medical Center in Rotterdam, the Netherlands, that followed 222 patients with hip osteoarthritis for two years, found no significant difference between glucosamine and placebo group in treating mild to moderate hip arthritis. The glucosamine treatment did not seem to be an effective treatment for patients with hip osteoarthritis and the differences between the glucosamine and placebo group were very small.