Supplements May Help Knee Arthritis
New Studies Give Mixed Signals About Glucosamine, Chondroitin Benefits
Nov. 14, 2005 -- Arthritis sufferers may -- or may not -- benefit from a pair of popular dietary supplements, two new clinical trials suggest.
One supplement is glucosamine, derived from the shells of crabs and lobsters. The other is chondroitin, usually derived from animal cartilage. These supplements are said to help relieve arthritis pain. They are also said to prevent the arthritic joint narrowing that causes one bone to grind against another.
Do these supplements really work? That is what two clinical trials -- a 1,583 patient study in the U.S. and a 318 patient study in Europe -- tried to find out. Researchers reported results from both studies at this week's annual scientific meeting of the American College of Rheumatology in San Diego.
"The supplements were not better than the placebo," Daniel O. Clegg, MD, tells WebMD. Clegg, chief of rheumatology at the University of Utah in Salt Lake City, led the NIH-sponsored U.S. study.
Arthritis Foundation spokesman Erin Arnold, MD, has a different interpretation. Arnold, a rheumatologist with the Illinois Bone and Joint Institute in Morton Grove, Ill., notes that Clegg is focusing on the study's overall results. She says she is more impressed with the study's finding that patients with more severe arthritis pain got significant relief from the glucosamine-chondroitin combination.
"I am very encouraged by the results of this study," Arnold tells WebMD. "The data presented certainly does not deter me from encouraging patients to try glucosamine and chondroitin."
There is less controversy over the smaller, European study led by Gabriel Herrero-Beaumont, MD, of the Jiminez Diaz Foundation in Madrid, Spain.
"Our results confirm previous studies," Herrero-Beaumont tells WebMD. "They demonstrate clearly that glucosamine was able to control knee osteoarthritis pain."
Glucosamine + Chondroitin: For Bad Arthritis Pain Only?
The U.S. trial enrolled patients aged 40 and older with knee pain due to osteoarthritis. They were randomly assigned to one of five treatments:
- Inactive placebo pills
- Glucosamine hydrochloride at a dose of 500 milligrams three times a day
- Sodium chondroitin at a dose of 400 milligrams three times a day
- Combination glucosamine and chondroitin
- Celebrex at a dose of 200 milligrams per day
It is common for a pain study to show that many patients report relief from inactive placebo pills. And that happened here. Nearly 60% of patients given only placebo pills said they had less pain. So did about 67% of patients treated with combination glucosamine and chondroitin. But that isn't what scientists call a significant difference -- that is, there's more than a 5% chance the findings are just coincidence.
"I really feel the study is a negative study," Clegg says. "I would say to patients that the safety data are really reassuring, the efficacy data are not."
When Clegg's team looked only at patients with moderate to severe pain. Only 54% of these patients got relief from placebo. But 79% reported relief from combination glucosamine and chondroitin. That is a significant difference. But there's a problem, Clegg says. The study wasn't designed to look at just this group. The effect here is based on only a small number of patients.
"About 20% of the study patients have moderate to severe pain," Clegg says. "Interestingly, in that subgroup, the combination of glucosamine and chondroitin appeared to be effective in relieving pain. I think this outcome is really interesting but just from a research standpoint. It is an exploratory, hypothesis-generating finding -- not a finding on which to base treatment."