Are glucosamine and chondroitin really effective in osteoarthritis?

(April 2001)

Degenerative arthritis (osteoarthritis) is the most common form of arthritis, afflicting more than 20 million Americans, most of them over age 50. The hips and knees are particularly affected, causing pain and limitation of motion. There are a variety of pain-killing medications and anti-inflammatory agents used to treat the arthritis, all treating the symptoms without affecting the underlying arthritis. In recent years, glucosamine, a substance important in the building of cartilage, has become immensely popular. It is now one of the most widely used of the dietary supplements, and is advertised as promoting joint health.

But, does it really work? Nobody knows for sure. The March 15, 2000 issue of the Journal of the American Medical Association includes a review of all major studies by Timothy E. McAlindon and his colleagues from Boston University. They also summarized the data on chondroitin sulfate, another substance important in building cartilage. Six European studies on glucosamine were summarized; taken together, they show a modest beneficial effect. Nine studies on chondroitin were summarized; taken together, they showed an even greater benefit. All the studies on both substances were focused on arthritis of the knees.

The authors’ conclusion is that "overall, it seems probable that these compounds do have some efficacy in treating osteoarthritis symptoms and that they are safe."

Commentary: This article will be used by the entrepreneurs to sell a lot more glucosamine and chondroitin. All of these studies were done in Europe and, in many of them, the authors were associated with the drug manufacturers. There is no analysis of the characteristics or age of those taking the supplements, and inadequate analyses on duration of treatment and dosage used. Then, there is the issue of an early bias in reporting - the tendency for positive studies to be published earlier than negative studies.

Osteoarthritis is a chronic disease that will probably require treatment for years. Yet, most of these studies have been for less than three months. However, a recent careful three-year study from Belgium of 212 persons with osteoarthritis, most of them women, average age 66 years, answers some of the concerns. During the three-year period, the 106 controls given an inactive material (placebo) showed progression of the knee osteoarthritis and had slightly worse symptoms. On the other hand, those given 1,500 milligrams of glucosamine daily showed no progression of the arthritis and improvement in symptoms. But, not everyone benefitted; 15 percent of those on glucosamine still developed marked progression of their disease. Symptom relief of some degree was found in almost all of those on glucosamine and appeared to last for the entire three-year study period.

Glucosamine and chondroitin do look interesting, and the long-term study is quite encouraging. They may indeed be beneficial and, so far, adverse reactions seem mostly to consist of abdominal discomfort and bowel problems. But, we still need more well-designed and controlled studies carried out for longer periods of time. One such controlled study of both glucosamine and chondroitin is being carried out by the National Institutes of Health. The dosage will be 1,500 milligrams of glucosamine and 1,200 milligrams of chondroitin daily. That seems to be an appropriate dosage schedule. Unfortunately, the duration of the study will be only four months; a longer study period would have been desirable.

So far, virtually all the studies are on osteoarthritis of the knees. Whether glucosamine-chondroitin will help osteoarthritis of the hips or the hands is not known.

There is another problem, and that is the available dosages and instructions at pharmacies and health food stores. For example, at the only pharmacy in a suburban New Jersey community, the joint health shelf had three separate glucosamine products from the same manufacturer:

(1) 600 milligrams - to be taken once a day

(2) 550 milligrams to be taken three times a day with water

(3) 1000 milligrams to be taken twice a day with water

Additionally, there was a combination of glucosamine 400 milligrams and chondroitin 500 milligrams to be taken as one to three tablets a day, preferably with meals.

How can the directions from the same manufacturer differ so dramatically - a range of 600 to 2,000 milligrams a day. The 600 milligram dosage is likely to be insufficient and ineffective (actually, we do not yet know for sure whether the larger doses are effective either).

A lot of consumers are going to be confused and misled. It is additional evidence of the undesirable consequences of an uncontrolled, entrepreneur-dominated dietary supplement market.

McAlindon, T.F., et al. Glucosamine and chondroitin for treatment of osteoarthritis. Journal of the American Medical Association. Vol 283. (March 15). Pgs 1469-1475. 2000.

Reginster, J.V., et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: A randomized, placebo-controlled clinical trial. The Lancet. Vol 357. (January 27) Pgs 251-256. 2001.