Taking glucosamine: not just a knee-jerk reaction

Evidence mounts for glucosamine's protective action against OA of the knee

By Samuel Munson

Health food aficionados have long proclaimed the benefits of glucosamine in blunting the aches of osteoarthritis (OA). But proof of the compound's medical oomph has been lacking. Now, a pair of European studies aimed at evaluating the influence of glucosamine on OA of the knee joint in postmenopausal women has found that the popular nutritional supplement may indeed live up to the hype. The results of the trials appear in the March/ April issue of Menopause.

The study analyzed a pair of three-year, multinational trials. At baseline and after the three-year diet of glucosamine or placebo, patients were sent to have radiographic pictures of their knees taken while standing to put stress on the joints. In the placebo group, the space in the knee joint decreased by an average of 0.33mm, likely due to the loss of the protective cartilage. However, those taking glucosamine actually experienced a statistically significant increase in the joint space by an average of 0.003mm.

Of the 414 people in the two trials, 319 were postmenopausal women. The women were randomly divided into two groups; one took glucosamine sulfate while the other a placebo. Both populations were similar in age and number of pre- and postmenopausal women. Even though the trials were done independently, they were designed so that the data could be combined for analysis.

Strangely, some women experienced a lessening of aches and pains even though their knee joint space decreased. Prevention of the joint space shrinkage, however, was only seen in those on the glucosamine-spiked diet.

More evidence for the protective action of glucosamine was revealed when the women's symptoms were scored on the gold standard Western Ontario and McMaster Universities Osteoarthritis Index function scale. Those taking glucosamine registered an improvement on the scale, while the placebo crowd's knee joints worsened.

Lead author of the Menopause Study, Olivier Bruyere, MSc from the World Health Organization's Collaborating Center for Public Health Aspect of Osteoarticular Disorders in Liege, Belgium, his and colleagues concluded that, for postmenopausal women with knee joint OA, glucosamine has "... a disease-modifying effect."

Osteoarthritis affects one in 10 Canadians � some 300,000 people � mainly over the age of 45, and is the most common cause of joint pain in both men and women.

Glucosamine is currently classified only as a nutritional supplement in Canada. "Efforts to standardize treatment would seem to be in order and physicians should open their minds to the use of nutritional products as therapeutic agents," wrote Dr Thomas Einhorn, of the Department of Orthopedic Surgery, Boston University School of Medicine, in an editorial that accompanies the Menopause paper. "In the absence of data to show significant adverse events from glucosamine, it is hard to argue against its use."

While glucosamine is assumed to stimulate cartilage formation, this still needs to be proven.