TUESDAY, Jan. 28, 2003 (HealthDayNews) -- A small study has found that daily doses of glucosamine, a widely available nutritional supplement, reduce discomfort and improve mobility in people with chronic knee pain.
However, the study, which appears in the February issue of the British Journal of Sports Medicine, is being criticized by outside experts.
"There are significant flaws in the study design," says Dr. Clifton Bingham, director of the Seligman Center for Advanced Therapeutics at the Hospital For Joint Diseases in New York City.
Glucosamine, an amino sugar that is produced naturally by the body and is present in joint cartilage, has been the subject of interest as a possible antidote for the pain of osteoarthritis.
According to the Arthritis Foundation, osteoarthritis, or "wear-and-tear" arthritis, currently affects nearly 21 million Americans and the number is rising. The condition, which involves the erosion of joint cartilage, is associated with aging and is most common in middle-aged and older individuals.
Due to lack of funds, this study did not look specifically at people with confirmed osteoarthritis, only people with chronic knee pain that was thought to be due to cartilage damage or osteoarthritis.
"We didn't have the funding to do MRIs or anything, but two-thirds of the subjects had had previous scans that indicated cartilage damage," says Rebecca Braham, lead author of the study, which was conducted while she was working as an exercise physiologist at the University of Western Australia in Perth.
Twenty-four of the study's participants were assigned to receive 2,000 milligrams of glucosamine. The remaining 22 patients were given a placebo.
Pain and mobility were assessed at regular intervals over the course of 12 weeks. While mobility improved in all patients, the improvement was seen more quickly in patients in the glucosamine group, beginning at four to eight weeks.
At the end of three months, 88 percent of those taking glucosamine reported a decrease in knee pain, compared with only 17 percent in the placebo group.
However, the method and results aren't wowing other researchers.
In addition to its small size, the study is "also using nonstandard doses of glucosamine, the safety of which has not been determined," says Bingham, who is currently recruiting for a multi-center National Institutes of Health trial to assess the efficacy of the supplement. "There's some data to suggest that high doses in diabetics may worsen diabetes." The standard dose of glucosamine is 1,500 milligrams per day.
The study authors did not find any significant side effects for the larger dose. "We found that side effects were fairly consistent between the groups," Braham says. "Some in each group had nausea and dry mouth, but nothing bad enough to warrant them coming out of the study."
"Glucosamine has anti-inflammatory properties as do all drugs given out for arthritis, and it does work in some people who respond to various other anti-inflammatories," says Dr. Daniel D. Ricciardi, chief of rheumatology at Long Island College Hospital in Brooklyn, N.Y. "Is it any better or worse than the poisons we give out today? We really don't know. Is it the end-all and be-all? No, it's just another drug in our armamentarium."
More information
The Arthritis Foundation has information on both osteoarthritis and glucosamine.
If you want more information on recruiting for Bingham's trial, call 866-HJD-DRUG.
