BETHESDA, MD -- In a study published in the New England Journal of Medicine, the popular dietary supplement combination of glucosamine plus chondroitin sulfate did not provide significant relief from osteoarthritis pain. However, a smaller subgroup of study participants with moderate-to-severe pain showed significant relief with the combined supplements.

The 4-year study, known as the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), was held at 16 sites across the United States. GAIT enrolled nearly 1,600 participants with documented osteoarthritis of the knee. Participants were randomly assigned to receive one of five treatments daily for 24 weeks: glucosamine alone (1500 mg), chondroitin sulfate alone (1200 mg), glucosamine and chondroitin sulfate combined (same doses), a placebo or celecoxib (200 mg). Celecoxib is an FDA-approved drug for the management of osteoarthritis pain and served as a positive control for the study. A positive response to treatment was defined as a 20 percent or greater reduction in pain at week 24 compared to the start of the study.

The researchers found that participants taking celecoxib experienced statistically significant pain relief, as expected, versus placebo -- about 70 percent of those taking celecoxib versus 60 percent taking placebo had a 20 percent or greater pain reduction. For all participants, there were no significant differences between the other treatments tested and placebo. However, for participants in the moderate-to-severe pain subgroup, glucosamine combined with chondroitin sulfate provided statistically significant pain relief compared to placebo -- about 79 percent in this group had a 20 percent or greater pain reduction compared to 54 percent for placebo. In the subgroup of participants with mild pain, glucosamine and chondroitin sulfate together or alone did not provide statistically significant relief compared to placebo.

"More than 20 million Americans have osteoarthritis, making it a frequent cause of physical disability among adults," said Stephen I. Katz, M.D., Ph.D., National Institute of Arthritis and Musculoskeletal and Skin Diseases director. "We are excited to support studies looking at new treatment options that could improve the symptoms and quality of life of people with osteoarthritis."