The National Institutes of Health conducted a $12.5 million study to determine whether two of the best-selling arthritis supplements, glucosamine and chondroitin sulfate, can ease osteoarthritis pain.
Due to limitations in the study design, however, that question still remains unanswered.
Called the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), the study enrolled 1,583 people over the age of 40 with knee pain due to osteoarthritis. Participants were given one of five treatments: glucosamine or chondroitin alone, a combination of glucosamine and chondroitin, the prescription drug celecoxib (Celebrex), or a placebo. The results:
- 64% who took 1500 mg a day of glucosamine had reduced pain
- 65% who took 1200 mg a day of chondroitin had reduced pain
- 67% who took 1500 mg glucosamine and 1200 mg a day chondroitin had reduced pain
- 70% who took 200 mg a day of Celebrex had reduced pain
- 60% who took the placebo had reduced pain
The researchers, led by Daniel Clegg of the University of Utah, say that the unusually large placebo rate may have obscured the benefits of glucosamine and chondroitin. In this study, 60% of people taking the placebo experienced a reduction in pain, double the usual placebo effect of 30%.
Treatments had to have a response rate 15% or higher than the placebo group response rate to be considered clinically effective, so a normally-impressive 67% pain reduction rate wasn't considered significant compared to the 60% placebo rate.
The researchers also analyzed people with mild pain and those with moderate-to-severe pain separately. Among the people with moderate-to-severe osteoarthritis pain, the combination of glucosamine and chondroitin provided significant relief from arthritis pain:
- 79.2% of people in the moderate-to-severe pain subgroup who took glucosamine and chondroitin combination had reduced pain.
- 54.3% in the moderate-to-severe pain subgroup who took the placebo had reduced pain.
So does that mean that glucosamine and chondroitin sulfate may help people who need it the most? Unfortunately, there was a disproportionate number of people with mild pain in the study, which may have obscured benefits yet again. Out of the 1,583 people in the study, only 22% (354 people) had moderate-to-severe pain and the rest had mild pain. Only 72 people in the moderate-to-severe subgroup received both glucosamine and chondroitin, too few to make a reliable conclusion.
People in the Celebrex group had a non-significant but higher incidence of increased adverse cardiac events, including blood pressure, palpitations, and irregular heartbeat. However, the researchers did not monitor blood pressure or do any other cardiac tests unless participants specifically reported an adverse event.
This study, the first of two parts, only looked at pain reduction over six months, a relatively short time period. In a 2002 study in the journal Archives of Internal Medicine, researchers examined patients over three years, and not only looked at pain but at structural improvements seen on x-ray. They gave 202 people with mild to moderate osteoarthritis either 1500 mg of glucosamine sulfate a day or placebo, and found that longer-term treatment with glucosamine slowed the progression of knee osteoarthritis compared to placebo. The glucosamine group experienced a significant reduction in pain and stiffness. On x-ray, there was no average change or narrowing of joint spaces in the knees (a sign of deterioration) of the glucosamine group. In contrast, joint spaces of participants taking the placebo narrowed over the three years.
Another criticism of the GAIT study is that it used a form of glucosamine called glucosamine hydrochloride. Many of the promising studies to date have used a different form of glucosamine called glucosamine sulfate.
According to the Nutrition Business Journal, glucosamine and chondroitin sales exceeded $1.7 billion in 2005.More Information
Clegg D, et al. Glucosamine, Chondroitin Sulfate, and the Two in Combination for Painful Knee Osteoarthritis. "New England Journal of Medicine", 2006; 354:795-808.
Pavelka K, Gatterova J, Olejarova M, Machacek S, Giacovelli G, Rovati LC. Glucosamine sulfate use and delay of progression of knee osteoarthritis: a 3-year, randomized, placebo-controlled, double-blind study. Arch Intern Med. 2002 Oct 14;162(18):2113-23.