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Glucosamine and chondroitin sulfate: What do the studies really say?

By Michael Gordon, MD, Milwaukee Orthopaedic Group, Ltd. Orthopedic Surgery, Sports Medicine Fellowship

A recent study sponsored by the National Institutes of Health evaluating the efficacy of glucosamine sulfate (GS) and chondroitin sulfate (CS) in treating arthritis has triggered much publicity. Reviews of the article were posted in most major newspapers, including The Milwaukee Journal Sentinel, and even landed on the Badgerland Striders web site. So what's with all of the fuss?

First, since the study was sponsored by the government and not by the supplement manufacturers, it limits much of the bias apparent in many other studies. Second, it was published in arguably the most respected medical journal in the world, The New England Journal of Medicine. Third, estimated sales for this industry topped over $730 million in 2004. Finally, these supplements are specifically targeted at people with arthritis, a population that will only continue to grow as baby-boomers age.

Critical to the understanding of the research is how it relates to your body, specifically your knees. Here's the quick anatomy lesson: the end of your bones are capped with a highly organized layer of articular cartilage. This structure functions both as a shock absorber, as well as providing a smooth gliding surface for bones to move by each other (i.e. the shin bone bends underneath the thighbone when you flex your knee). Things get interesting when you take a closer look at the cartilage. Since cartilage has no blood supply, all of its "nutrition" comes from the fluid that lines, as well as lubricates the joint. Cartilage is composed of a dense web-work of fibers – filling in all of the spaces are highly charged little balls.

Glucosamine and chondroitin sulfate are the building blocks for these components of the cartilage.

Arthritis, by definition, is the breakdown of the articular cartilage causing a disruption of the balance created by this very precise structure. Even though we have multiple tools in our belt to treat arthritis, no medications have been shown to slow down the progression of the disease. Many patients take anti-inflammatories (i.e. Advil, Aleve, Celebrex, etc.) with good success, but unfortunately these drugs do not alter the course of the arthritis, rather they directly address the symptoms.

This is where GS and CS come in to play. For years, these nutritional supplements have been used in other countries with good anecdotal success in controlling patients' arthritic symptoms. In addition, several studies have demonstrated that use of these products can slow down the progression of arthritis (or halt it) over a three-year period. Based on these reports, a strong push was made for a well-controlled study to be performed in the U.S. The 6-months results from this study were just released in January.

The headlines blared that GS and CS supplements showed no statistically significant benefits when compared to a placebo (a "dummy" pill), except in a small subset of patients with moderate to severe arthritis. On first review of the paper, the data supports this outcome. However, the study has several significant flaws that make the results difficult to fully interpret.

First, they found that 60% of the patients receiving the placebo showed a positive response and got better. That's more than twice the accepted standard for a medical study. Second, the study utilized glucosamine hydrochloride, not the more commonly used glucosamine sulfate. Third, all participating patients had to have at least 6 months of symptoms, as well as x-ray changes consistent with arthritis. Sadly, this study did not include many of the patients to which we recommend these supplements. Finally, the reported data is not consistent with many studies that have been published worldwide over the past several years in other respected journals.

At this point in time, I am continuing to recommend these supplements to my patients with confidence in their potential benefit. I utilize them for patients with arthritis, as well as for my runners/athletes with "aching knees" and patellofemoral chondromalacia ("anterior knee pain"). I believe the studies that examine the cellular response in the joints themselves are highly suggestive that GS and CS have a cartilage "stabilizing" effect. In addition, I have had enough patients demonstrate a positive response, including myself, that I believe these supplements merit further study.

Overall, the safety profile relative to GS and CS supplements appears to be very good with most of the reported side effects being minor. That being said, there are several patient groups that should not take these products: people taking blood thinners, those individuals with a history of a shellfish allergy and/or a history of diabetes. As with any over-the-counter medicine, please discuss the addition of supplements such as these with your physician as they can interact with other medications.

If you do decide to add GS and CS to your daily routine, it will take about three months of continuous usage to experience much benefit, and any changes that you notice will be subtle in nature. Since the FDA does not categorize these drugs, they are not federally regulated. Before purchasing, speak to your pharmacist about which products he/she recommends, rather than buying the cheapest brand on the shelf.

Dr. Michael Gordon, of the Milwaukee Orthopaedic Group, Ltd. is an orthopedic surgeon with a fellowship in sports medicine. For questions, you can reach Dr. Gordon at 414-276-6000.