Researchers have been debating for years whether that's a good idea. Now, the largest study yet suggests you're better off saving your money unless you have a moderate-to-severe case of osteoarthritis. And even then it's not clear if the supplements work.
But there's some good news. Glucosamine and chondroitin -- a staple of health food stores -- may help with moderate to severe pain, U.S. researchers were to report at the American College of Rheumatology annual meeting in San Diego.
The supplements "seem to be safe, but the bottom line for the overall patient population is that there wasn't a difference" compared to not taking them at all, says study co-author Dr. Daniel Clegg, chief of rheumatology at the University of Utah School of Medicine. He added that the findings were preliminary.
Good news for glucosamine and chondroitin
But a smaller European study came to an opposite conclusion, suggesting that glucosamine may actually work better than the painkilling ingredient in Tylenol.
An estimated 21 million adults in the United States have osteoarthritis, which is caused by wear and tear on cartilage in the joints. Some evidence has suggested that glucosamine, a natural substance found in bone, helps the body repair itself. Another natural substance, called chondroitin sulfate, has also been considered a possible arthritis reliever.
Over-the-counter and prescription painkillers can help relieve the pain of arthritis, but they don't always make it go away completely.
In the new U.S. study, researchers followed almost 1,600 patients with painful knee osteoarthritis for six months. The patients were randomly assigned to different treatments -- glucosamine hydrochloride, chondroitin sulfate, the painkiller celecoxib (sold as Celebrex), or a placebo. Regardless of what drug or supplement they took, they were allowed to take daily doses of the painkiller acetaminophen (sold as Tylenol).
Celecoxib relieved pain, but the supplements did not for a majority of the patients, and neither of them did a better job than a placebo, Clegg says.
However, there is a glimmer of hopeful news. The study indicated that a combination of glucosamine and chondroitin might help patients with moderate or severe osteoarthritis. Those patients made up about 20 percent of participants in the study; the other 80 percent had milder forms of the disease, Clegg says.
"From a research standpoint, these are really interesting results," he says. But the findings are only preliminary. "I think we need more information," he adds.
In response to the research, the Arthritis Foundation says in a statement that it "believes that, based on the findings from this study and the supplements' safety and cost-effectiveness, the combination of glucosamine and chondroitin should be considered by patients and physicians as part of an overall treatment plan for painful knee OA.
Further research is needed to determine exactly how glucosamine and chondroitin work, as well as the possible effectiveness of these supplements on limiting the progression of cartilage damage."
Glucosamine sulfate, selenium
In the second study, also to be released at the American College of Rheumatology conference, European researchers were to report that glucosamine sulfate -- a different form of the supplement than used in the American study -- did a better job of treating pain from knee arthritis than acetaminophen. The study looked at 318 patients, mostly women, who took the supplement, acetaminophen or a placebo.
In other arthritis news, researchers were to report at the rheumatology meeting that they've uncovered an apparent link between the mineral selenium and arthritis in patients.
Selenium is found in corn, wheat, soybeans, animal products and other foods, the researchers say. In some parts of the world, selenium deficiency has been connected to arthritis.
Researchers decided to look at an American group of arthritis patients by analyzing toenail clippings from 940 residents of Johnson County, a semi-rural region of North Carolina. Selenium builds up in toenails over time, allowing researchers to estimate the levels of the mineral.
The findings? "The lower the selenium level, the more likely you were to have more severe arthritis. And you were more likely to have it in both knees instead of one," says Dr. Joanne M. Jordan, associate professor of medicine and orthopedics at the University of North Carolina.
It's not clear if selenium supplements would help treat or prevent arthritis. Most Americans get enough in their diets, Jordan says.
Still, the study "gives us the idea of something we can go after to help people with their arthritis," she says.
The HealthDay Web site is at http://www.HealthDay.com.