This quest has turned glucosamine and chondroitin into superstars of the supplement industry. With U.S. sales about $1 billion annually, the compounds have a popularity to rival just about any prescription drug. Sold separately or together, they're available at drug stores, grocery stores and health food stores everywhere.
Once scientists discovered these substances, it didn't take a huge leap of logic to speculate that the pair might help treat or prevent osteoarthritis, the wear-and-tear variety of joint trouble that comes with age.
Anyone who wants to take glucosamine and chondroitin has plenty of options. Move Free Advanced Triple Strength tablets includes 1,500 milligrams of glucosamine and 200 milligramsof chondroitin. Take two tablets a day as directed, and you can expect to pay about $20 or more for a one-month supply. Osteo Bi-Flex combines 1,500 milligrams of glucosamine with 1,250 milligrams of a blend of chondroitin and MSM, another natural compound that the company says eases joint pain. At a recommended dose of three caplets a day, you can pay about $30 a month. Flexicose, a liquid supplement, contains 1,500 milligrams of glucosamine and a smattering of chondroitin and other ingredients per dose. You'd pay about $30 monthly.
Though glucosamine and chondroitin can be cooked up in a lab, most supplements use animal sources. Osteo Bi-Flex, for example, contains glucosamine from crustaceans (crabs, shrimp and crayfish) and chondroitin from cow cartilage.
The claims: Glucosamine and chondroitin are often promoted as safe, natural and effective alternatives for arthritis relief. The website for Osteo Bi-Flex claims that glucosamine and chondroitin are clinically proven to "improve joint health, comfort, range of motion and mobility." The Flexicose site says that the product will "help you get your life back because it works fantastically. Most users notice a significant drop in discomfort in only one to two weeks." The site also contends that Flexicose has a "whopping 98% success rate."
The bottom line: Dr. Tim McAlindon, chairman of rheumatology at Tufts Medical Center in Boston, used to see real potential in glucosamine and chondroitin supplements. He even said so in the Journal of the American Medical Assn. in 2000. But after a series of disappointing results in well-designed studies, McAlindon says, he has "grown more and more skeptical." "I no longer suggest that my patients even try these products. They don't work."
Some glucosamine/chondroitin studies over the years have had positive results, but McAlindon isn't convinced. That's because as a rule, he says, the investigations that showed benefits were funded by supplement companies. Independent studies generally suggest that glucosamine and chondroitin have little to no effect on arthritis.
The largest independent study, known as Glucosamine/chondroitin Arthritis Intervention Trial, or GAIT, wasn't exactly a triumph. Researchers at the University of Utah tested the supplements on more than 1,500 patients with osteoarthritis of the knee. Each patient received either 1,500 milligrams of glucosamine, 1,200 milligrams of chondroitin, a combination of glucosamine and chondroitin, 200 milligrams of the pain reliever Celebrex or a placebo. Pills were taken every day for six months.
As reported in the New England Journal of Medicine in 2006, glucosamine and chondroitin worked no better than placebos overall, although the combination did seem to help patients in the most pain. Nearly 80% of these patients reported some improvement, compared with 50% of patients taking a placebo.
Although the current scientific evidence is far from convincing, glucosamine supplements -- but not chondroitin -- might still be worth a try, says Dr. Scott Zashin, a clinical assistant professor at the University of Texas Southwestern Medical Center and a member of the American College of Rheumatology.
"I think some patients do experience benefits," he says. He recommends 1,500 milligrams of glucosamine a day for those who want to try it. "I tell them to try it for a few months to see if they feel better."
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