Two nutritional supplements that some believe may help treat the degenerative disease osteoarthritis, glucosamine and chondroitin are widely used by elderly people who suffer from the pain and stiffness associated with the disease. While studies have had contradictory results, some doctors and patients believe strongly in the supplements’ healing potential.

Glucosamine is found naturally in the body, but production decreases with aging. Supplements are derived from the shells of shrimp, crabs, and other shellfish. Glucosamine has also been suspected (though not proven) to help treat diabetes, inflammatory bowel disease, psoriasis, leg pain after injury, and chronic venous insufficiency (a syndrome that includes leg swelling, varicose veins, pain, itching, and skin ulcers).

Chondroitin typically comes from cow or shark cartilage and is often marketed under the name chondroitin sulfate. A carbohydrate, chondroitin appears to improve water retention, fight inflammation, and counter the breakdown of cartilage in the human body.

Study results on the effectiveness of glucosamine and chondroitin have not always been favorable: The largest and best-designed clinical trial on this topic—the ongoing Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), funded by the National Institutes of Health—has found no benefit compared with a placebo in reducing pain or loss of cartilage (as measured by x-rays) in osteoarthritis patients. However, smaller studies have shown significant improvement in patients taking the supplements, especially for osteoarthritis of the knee. Whether glucosamine and chondroitin offer any advantages over pain relief medications such as acetaminophen, traditional nonsteroidal anti-inflammatory drugs, or COX-2 inhibitors has not been determined.

Glucosamine and chondroitin tend to be well tolerated, although side effects can include upset stomach, drowsiness or insomnia, headache, sun sensitivity, and nail toughening. Based on some research, glucosamine may increase the risk of bleeding when taken with blood-thinning medications, and it may increase the risk of cataracts. Taking glucosamine and chondroitin with bromelain, manganese, or vitamin C may enhance the supplements’ beneficial effects on osteoarthritis, but this remains unproven.

ADDITIONAL FACTS

  1. Animal research has raised the possibility that glucosamine may worsen insulin resistance, a major cause of diabetes. No human studies have substantiated the risk so far, but to be safe, people with diabetes should monitor their blood sugar levels while using the supplement.
  2. There have been no reports of allergies to glucosamine, but because it is made from shellfish shells, people with seafood allergies should use it cautiously and watch for reactions.
  3. In 2008, a Scottish newspaper reported that a few people had died of liver failure within weeks of taking glucosamine. Though physicians weren’t sure why this happened, they issued a warning about glucosamine.