Osteoarthritis is a painful condition associated with the deterioration of cartilage, the flexible connective tissue that cushions the joints between bones. When cartilage wears away, bone painfully rubs on bone. The idea of using glucosamine to treat osteoarthritis stems from the observation that glucosamine formed naturally in the body is the precursor for the biosynthesis of glycosaminoglycans, major components of cartilage. Perhaps supplementing the body’s supply of glucosamine would help repair cartilage, the thinking went. But thinking, even if scientifically rational, is not evidence. And this is where we run into difficulties with glucosamine. While some early studies showed a benefit, more recent larger and better controlled trials have failed to live up to the original optimism.
Glucosamine comes in two possible forms, the sulphate or the hydrochloride. The hydrochloride actually yields more glucosamine in the body but practically speaking the difference is not much. Low back pain can often be caused by osteoarthritis and glucosamine supplements are widely promoted for this condition. A placebo-controlled study using 1500 mg of glucosamine sulphate showed no difference between the experimental and the placebo groups, but both groups did show some improvement. Results seem to be somewhat better when glucosamine is combined with chondroitin, a substance isolated from pig or cow cartilage. It is thought to improve the elasticity of cartilage and to inhibit enzymes that break it down. This combination helps to ease moderate to severe knee pain in osteoarthritis patients but is not useful for mild pain.
Glucosamine is relatively easy to isolate and purify so that the amounts declared on a label tend to be close to correct, but chondroitin is another story. Purification of this substance is more difficult and some supplements contain much less than the amount listed on the label. The usual dosing directions are 750 mg of glucosamine and 600 mg of chondroitin to be taken twice a day. An effect, if there is to be one, may take several weeks to kick in. If there is no observable improvement after three months, there won’t be any. Glucosamine is safe enough, but is not totally risk free. Some products have been found exceed the daily limit of 0.5 mcg of lead. Researchers at Laval University found that glucosamine, albeit at significantly higher doses than recommended for humans, caused pancreatic cell death in the laboratory. The implication of this for people is not clear, but the study does suggest that recommended doses should not be exceeded. That warning has relevance because many osteoarthritis patients increase their dosage beyond recommended levels when they do not experience the expected results. Since osteoarthritis treatments leave a lot to be desired, patients can’t be blamed for giving a combo of glucosamine and chondrotin a shot. At the very least, they have a good chance of experiencing a placebo effect.