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Popular Supplements Don’t Slow Progression of Osteoarthritis

Osteoarthritis is thought to affect at least 21 million Americans, oftentimes bringing crippling pain and limited mobility.  To relieve the pain and slow the progression of the disease, many people turn to glucosamine and chondroitin sulfate supplements but a recent study suggests no clinically documented improvement when these supplements were taken separately or in combination over the two-year study period.

The severity and progression of osteoarthritis is assessed by measuring the rate of joint space width loss, which is the loss of cartilage at the end of the bones in an arthritic joint as seen using x-ray technology.  The progressive loss of cartilage in the joint marks the progression of the disease.

Allen D. Sawitzke, MD, led the study, which was an extension of a six-months-long study known as GAIT (Glucosamine/chondroitin Arthritis Intervention Trial), which concluded in 2006.  When asked to extend the study for an additional 18 months, 357 original GAIT study patients, with 581 arthritic knees, agreed.  Sawitzke, a rheumatologist, is an associate professor of internal medicine at the University of Utah School of Medicine.

Patients in the extended study continued taking the medication they were randomly assigned in the original study.  Some patients took 500 milligrams (mg) of glucosamine three times every day; others took 400 mg of chondroitin or a combination of the two supplements on the same schedule.  A fourth group took 200 mg of celecoxib (Celebrex) every day and a fifth, control, group took a placebo.

Joint space width loss was measured by x-rays taken at the beginning of the trial, at the one-year mark, and again at the completion of the trial.  Researchers expected to find joint width loss measuring 0.4 millimeters (mm) at the end of the two-year study but none of the patients lost that much cartilage.  The research team set the threshold for progression at 0.2 mm or less over the course of the study, meaning any loss less than 0.2 mm would indicate a slowing of disease progression.

None of the groups, including the placebo group, lost that much cartilage over the course of the study.  Cartilage loss per group was measured as:

• Glucosamine - 0.013 mm;
• Chondroitin sulfate - 0.107 mm;
• Glucosamine/chondroitin sulfate combo - 0.194 mm;
• Celecoxib - 0.111 mm; and
• Placebo - 0.166 mm

The study results left researchers to conclude that none of the agents under study produced a statistically significant difference in the rate of joint space width loss during the two-year period although the study provided insights that are expected to be important for future research.

The research team has published the findings of this study in the October issue of the medical journal, Arthritis & Rheumatism.  The study was funded by the National Center for Complementary and Alternative Medicine and the National Institute of Arthritis and Musculoskeletal and Skin Diseases, both subsidiaries of the National Institutes of Health.

Source: University of Utah Health Sciences

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