Many people use the popular dietary supplements glucosamine and chondroitin sulfate to treat osteoarthritis. But a new study sponsored by NIH shows that these substances—which are naturally found in and around cartilage—may not work as well as many hoped. 

Researchers led by rheumatologist Dr. Daniel O. Clegg of the University of Utah School of Medicine enrolled nearly 1,600 people with osteoarthritis of the knee in the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT). They were randomly assigned to receive 1 of 5 treatments for 24 weeks: glucosamine, chondroitin sulfate, glucosamine and chondroitin sulfate combined, a placebo or celecoxib, a pain medication.

Those taking celecoxib had less pain after 24 weeks than those taking placebo.  However, there were no significant differences between the other treatments and placebo. When the researchers looked closer, glucosamine combined with chondroitin sulfate did provide pain relief for a smaller subgroup of people with moderate-to-severe pain.

Because of the small number of people in the moderate-to-severe pain group, however, Clegg commented that the findings “should be considered preliminary and need to be confirmed in a study designed for this purpose.”

Measures of pain over a 24-week period don’t rule out the possibility that these compounds may still help with osteoarthritis. The GAIT team is continuing their research to examine whether glucosamine and chondroitin sulfate can delay the progression of osteoarthritis. The results of that study are expected in about a year.