Glucosamine and Chondroitin Sulfate Study Results Announced
Over 20 million Americans suffer from osteoarthritis (OA). This number is likely to double over the next two decades, as the population ages. People have become increasingly interested in CAM approaches that might slow OA's progression and reduce its pain, inflammation, and disability. NCCAM is sponsoring a number of studies in this area.
One of NCCAM's largest studies has found that, overall, glucosamine and chondroitin sulfate--alone and in combination--did not provide significant relief from pain of knee OA. However, a small group of participants with moderate-to-severe pain did experience significant relief from glucosamine combined with chondroitin sulfate.
NCCAM and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), two components of the National Institutes of Health, funded this 4-year nationwide study known as the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT). Researchers led by rheumatologist Daniel O. Clegg, M.D., of the University of Utah School of Medicine, Salt Lake City, conducted it at 16 sites across the United States. The results appeared in the February 23, 2006, issue of the New England Journal of Medicine.
Credit: National Institute of Arthritis and Musculoskeletal and Skin Diseases
Osteoarthitis . . .
Is the most common form of arthritis
Cost the American public over $86 billion in 2004
Is more common in women and in people who are older or obese
Mostly affects cartilage--firm, flexible tissue that covers the ends of the bones, keeps them from rubbing against each other, and absorbs impact
Erodes cartilage
Causes pain, swelling, stiffness, and sometimes disability
An Interest in CAM Approaches
There are conventional drug treatments that offer relief of OA pain, but they can pose problems. For example, nonsteroidal anti-inflammatory drugs (NSAIDs), a type of pain reliever, can cause gastrointestinal upset and bleeding. Also, there have been some reports of potential cardiovascular problems from the class of NSAIDs called COX-2 inhibitors (these block an enzyme in the body that stimulates inflammation).
In an interview with CAM at the NIH, Dr. Clegg explained why he became interested in doing the study: "I wanted to help my OA patients. I saw lots of them taking glucosamine and chondroitin sulfate alone or in combination, with no evidence to support their use. So we sought to answer the key question: Do glucosamine and/or chondroitin sulfate work to relieve the pain of osteoarthritis?"
Glucosamine and chondroitin sulfate are among the most sought-after CAM approaches for arthritis. Americans spent about $730 million in 2004 on these products. According to the largest national survey so far of Americans' use of CAM, arthritis was among the top reasons the participants used CAM. In addition, glucosamine with or without chondroitin was among the top "nonvitamin, nonmineral, natural products" used.
A Closer Look at These Supplements
Both glucosamine and chondroitin sulfate are natural substances found in and around the cells of cartilage. For dietary supplements, glucosamine is usually obtained from the shells of shrimp, lobster, and crabs, and chondroitin sulfate from the cartilage of sharks and cattle. Both substances can also be made in the laboratory. They are sold individually, in combination with each other, and in other combinations.
Dietary supplements are not regulated by the U.S. Food and Drug Administration (FDA) in the same way as prescription drugs. Thus, Dr. Clegg's team took a novel approach (for a dietary supplement study) to increase the validity of their results. "We looked at the products on the market and were unable to identify products that met the pharmaceutical standards mandated by the trial," said Dr. Clegg. "Using current Good Manufacturing Practices, we developed glucosamine and chondroitin products that met FDA standards for pharmaceuticals."
The Study Is Launched
Over 1,500 people joined the study. All were age 40 or older and had OA of the knee, mild or moderate-to-severe knee pain, and a loss of cartilage in the affected knee. They were assigned at random to receive, for 24 weeks, either glucosamine alone, chondroitin sulfate alone, glucosamine and chondroitin sulfate combined, celecoxib, or a placebo (a "sham" treatment with no active ingredients).
When the study concluded, here is what the researchers found:
Looking at the group of participants as a whole, there were no significant differences between any of the supplements tested and the placebo.
For participants with mild pain, glucosamine and chondroitin sulfate alone or together did not provide significant relief compared with placebo.
For a small group of participants with moderate-to-severe pain, glucosamine combined with chondroitin sulfate provided significant pain relief compared with placebo. However, because of this group's small size, the researchers noted that this finding should be considered preliminary and needs to be confirmed in further studies.
Participants taking celecoxib experienced significant pain relief, as expected, compared with placebo. Celecoxib also provided faster relief than any of the supplements (when the supplements provided relief).
"Side effects of the supplements were minimal and mild, such as an upset stomach," said Dr. Clegg. "But a much longer period of study will be needed to fully determine the long-term effects of these products, how they work in the body, and what explains their possible clinical benefits."
Dr. Clegg is overseeing a continuing study of about one-half of the GAIT participants to find out whether these same treatments can reduce or stop the progression of OA. These results are expected in about a year.
Translating the Results Into Practice
© Frances Twitty
Water aerobics and swimming are two types of exercise that can be helpful for OA. CAM at the NIH asked Dr. Clegg what he thinks these results mean for people with OA. "Conventional treatments such as prescription drugs, graded exercise, weight loss when appropriate, physical therapy, and patient education will remain key therapies for OA," he replied. "Patients should talk to their health care provider about all their treatment options." He added that if they have substantial pain and are interested in glucosamine and chondroitin sulfate, they should discuss with their provider whether those supplements would be appropriate. "People need to remember that supplements are not regulated like prescription drugs, and product quality can vary," he noted.
Stephen E. Straus, M.D., Director of NCCAM, views the study as a landmark in NCCAM's short history. "The year 2006 marks our seventh anniversary of building a portfolio of rigorous research on CAM therapies," said Dr. Straus. "This is our largest study to date. It demonstrates our commitment to study dietary supplements and other CAM therapies with well-designed research, to find out what works and what does not for compelling needs in public health. We now know that this supplement combination may offer an additional option to some patients, although much more remains to be learned about glucosamine and chondroitin sulfate."
References
Barnes PM, Powell-Griner E, McFann K, Nahin R. Complementary and alternative medicine use among adults: United States, 2002. CDC Advance Data Report #343. 2004.
Clegg DO, Reda DJ, Harris CL, et al. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. New England Journal of Medicine. 2006;354(8):795-808.
National Institute of Arthritis and Musculoskeletal and Skin Diseases. Handout on Health: Osteoarthritis. National Institute of Arthritis and Musculoskeletal and Skin Diseases Web site. Accessed at niams.nih.gov on February 28, 2006.
National Institute of Arthritis and Musculoskeletal and Skin Diseases. Questions and Answers About Arthritis and Rheumatic Diseases. National Institute of Arthritis and Musculoskeletal and Skin Diseases Web site. Accessed at niams.nih.gov on February 28, 2006.
For More Information
Additional details about GAIT can be found on the NCCAM Web site at nccam.nih.gov/research/results/gait.
The NCCAM Clearinghouse provides information on CAM and on NCCAM, including publications and searches of Federal databases of scientific and medical literature. The Clearinghouse does not provide medical advice, treatment recommendations, or referrals to practitioners.
To contact the National Institute of Arthritis and Musculoskeletal and Skin Diseases Clearinghouse, call 1-877-226-4267 (toll-free in the U.S.) or go to www.niams.nih.gov.
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