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.
By