A Dietary "Magic Bullet" for Cartilage?

Many athletes are ingesting glucosamine in the belief that this dietary supplement will help to protect their cartilage against damage from exercise. Individuals who want a "magic bullet" for arthritis are downing the supplement based on advice given in the book The Arthritis Cure, a best seller written by Jason Theodosakis, MD of the University of Arizona College of Medicine in Tucson. Unlike traditional treatments for osteoarthritis which focus on decreasing pain and improving movement, Theodosakis claims that the dietary supplements glucosamine and chondroitin sulfate work together to rebuild damaged cartilage and halt the progression of the disease.

Glucosamine, a substance synthesized by the body, does play a major role in the maintenance and repair of cartilage. It is thought that glucosamine stimulates cartilage cells to synthesize the glycosaminoglycans and proteoglycans that are the building blocks of cartilage. Glucosamine has also been reported to have anti-inflammatory properties by inhibiting the activity of proteolytic enzymes that contribute to cartilage breakdown (see Tufts University Health & Nutrition Letter, 1997).

Chondroitin is also naturally present in cartilage and composed of repeating units of glucosamine with attached sugar molecules. Theodosakis claims that chondroitin sulfate and glucosamine supplements work synergistically to combat the enzymes that cause cartilage degeneration. However, most of the research has focused on glucosamine and no human research has evaluated the glucosamine/chrondroitin combination.

Interest in glucosamine’s potential as an arthritis treatment was initiated in the early 1980’s when a number of controlled human studies were conducted in Europe and Asia (see Bucci, 1994). Although these studies were small and short-term, many patients reported relief from pain and ease of movement after taking 1.5 grams of glucosamine in divided doses daily. However, further research is required to determine if glucosamine can provide long term symptomatic benefits. There is also the important and unanswered question of whether glucosamine can stop or retard the process of cartilage deterioration and stimulate cartilage growth.

The research studies on glucosamine indicate that the supplement is most effective for early or less severe arthritis and less helpful for severe or late arthritis. Apparently, glucosamine cannot influence the repair of cartilage when there is insufficient (or no) cartilage on joints. There is no evidence that glucosamine interferes with the action of anti-inflammatory or analgesic medications. Preliminary animal research suggests that glucosamine may even protect against the long term, catabolic effects induced by some anti-inflammatory drugs (see Bucci, 1994).

Since glucosamine and chondroitin sulfate are dietary supplements, they are not required to undergo the rigorous safety and effectiveness testing that the Food and Drug Administration requires for drugs. Without FDA premarket review and approval, there is no guarantee that the claims made for the two supplements are accurate. Furthermore, federal regulations and monitoring of dietary supplements are so lax that a company can put some pills into a bottle, label them glucosamine, and charge a premium for them.

Researchers at the University of Maryland at Baltimore were hired by the publisher of The Arthritis Cure to analyze 23 different products that supposedly contain glucosamine. The book lists 15 of these that Theodosakis says were tested by the Maryland researchers and found to contain essentially what their labels claimed. However, the researchers were unable to test for N-acetyl glucosamine (and so could not determine the total amount of glucosamine) in three of the listed products. To make matters worse, the researchers noted that some of the products listed contained amounts of glucosamine that varied significantly from the amounts stated on their labels (see Tufts University Health & Nutrition Letter, 1997).

In a May 14 news release, the Arthritis Foundation recommended that consumers steer clear of The Arthritis Cure and emphasized that long-term, controlled studies are required to ascertain the safety and efficacy of glucosamine and chondroitin sulfate. The Arthritis Foundation notes that the title of the book is deceptive since not enough is known about the supplements to refer to them as a cure. The Arthritis Foundation recommends that patients consult their doctor for proven treatments that reduce arthritis pain and help disease management (see Arthritis Foundation, 1997).

 

References

Arthritis Foundation. An answer to The Arthritis Cure. May 14, 1997. Arthritis Foundation web page (http://www.arthritis.org) news release.

Bucci, LR. Nutrition Applied to Injury Rehabilitation and Sports Medicine. CRC Press. 1994; 195-203.

Is there an arthritis cure? Tufts University Health & Nutrition Letter. April 1997, volume 15, number 2.

 

Ellen Coleman, RD, MA, MPH
ellen@cruciblefitness.com