In the latest of an ongoing series of studies, European researchers studied the effect of glucosamine specifically in postmenopausal women already diagnosed with knee osteoarthritis. After age 50, knee osteoarthritis becomes more common in women -- possibly because of waning estrogen levels although medical research has not yet shown that, say the researchers. Osteoarthritis, caused by degeneration of cartilage that occurs with age, is the most common type of arthritis.
"What we found in studying postmenopausal women is what we found with our other population groups -- glucosamine sulfate certainly prevents the destruction of cartilage, slows progression of osteoarthritis, and improves symptoms of the disease," researcher Lucio C. Rovati, MD, of the University of Milano, tells WebMD. "And it may also rebuild cartilage in some people."
His new findings, published in the March/April issue of Menopause, come from two studies involving 414 women with knee osteoarthritis, most of whom had already experienced menopause. Half took 1,500 milligrams of glucosamine sulfate daily while the other women took a placebo. After three years, those taking glucosamine had experienced no further loss of cartilage as measured by knee X-rays, whereas the placebo group continued to experience cartilage destruction.
In addition, pain and function significantly improved among the women taking glucosamine compared with the placebo group where there was no such improvement in knee stiffness seen.
This improvement is of major clinical significance in terms of well-being, says Rovati, a professor of pharmacology. "The condition of women taking a placebo pill, meanwhile, worsened."
In previous studies, published in Archives of Internal Medicine and The Lancet, Rovati's team -- who include researchers from Belgium and the Czech Republic -- found similar levels of improvements when the same daily dosage was given to men and younger women with knee osteoarthritis.
What makes his new findings so important is that following menopause, rates of knee arthritis skyrocket in women. Up until now, that group of women had not been specifically studied, although postmenopausal women have been included in previous studies.
"There is certainly a good reason to believe that estrogens are important for cartilage, and this continues to be an active area of interest -- determining exactly how menopause impacts osteoarthritis," says John H. Klippel, MD, head of the Arthritis Foundation.
"What's really unique about this study is that they are able to look at a relatively homogeneous population -- postmenopausal women, as opposed to the whole world of osteoarthritis -- and have been able to confirm that in this population, glucosamine improves function and retards (measurable disease) progression."
All Joints Can Benefit
Rovati says his findings are the latest to show what his research team has long suspected: "Based on our studies and others, it appears that everyone with knee osteoarthritis can benefit from glucosamine sulfate," he tells WebMD. "And we suspect that this data can be transferable to all weight-bearing joints. The reason we and others primarily study knee osteoarthritis is because it's the most common type and there are more patients."
Glucosamine is naturally produced by the body and found primarily in joint cartilage, where it's believed to help maintain joint health and resilience. Although glucosamine supplements have long enjoyed a reputation for easing knee pain, only recently have they garnered convincing scientific evidence to back up these claims.
These supplements, which are not regulated by the FDA, contain glucosamine extracted from tissues of shellfish. They come in two forms: glucosamine sulfate, like that used in Rovati's studies, and glucosamine hydrochloride.
"The difference between the two is the added salts used," says Klippel, former clinical director of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. "Glucosamine is the active ingredient, so one would suspect a similar result from either type." The prescription product used in Rovati's study is chemically similar to glucosamine sulfate products sold in the U.S., but did not contain chondroitin or methylsulfonylmethane (MSM), as many do.
Still, Klippel tells WebMD that there is no evidence to indicate that glucosamine should be taken as a preventative measure before menopause onset, to reduce a woman's later risk of knee problems. "On the other hand, this study confirms that if you already have osteoarthritis, taking glucosamine may be a good thing to do."
But it may not be enough: "Although glucosamine may be helpful, it's also part of a much larger treatment plan -- and that should include weight management and physical activity," says Klippel. "Both are important, not only to reduce the risk of osteoarthritis, but also reducing symptoms once it has been diagnosed."