Glucosamine and chondroitin, taken either on their own or in combination, have been widely promoted as dietary supplements for osteoarthritis. For many years they have been used as veterinary products to treat arthritis in animals, and have become popular in recent times due to widespread publicity.
These substances both occur naturally in the body and appear to be involved in the formation and repair of cartilage. Taking them as supplements is believed to improve the formation of substances in the cartilage that are lost in the initial biochemical changes associated with osteoarthritis.
The glucosamine found in supplements is extracted from the shells of crustaceans (shellfish) or produced from vegetable matter. Chondroitin is usually derived from cow or shark products. Glucosamine is available in many forms, including glucosamine hydrochloride and glucosamine sulfate. Chondroitin is available as chondroitin sulfate.
Early trials evaluating glucosamine and chondroitin for the treatment of osteoarthritis have shown positive effects, but the beneficial effects may have been exaggerated because of poor design in some cases and the fact that studies with negative effects are less likely to be reported.
More recent studies have shown variable results. A large study of more than 1500 people with osteoarthritis of the knee found no differences in knee pain between those treated with glucosamine hydrochloride, chondroitin, or a combination of the two, or placebo (fake pills). However, another study, using a different from of glucosamine (glucosamine sulfate), found that this preparation was beneficial in people with knee osteoarthritis.
There have only been a few studies of glucosamine or chondroitin in people with osteoarthritis in other body areas, such as the hip, spine or hands, or in people with rheumatoid arthritis.
Glucosamine is an amino sugar, therefore concerns have been raised that it may contribute to insulin resistance, and it should be taken with caution by people with diabetes.
In addition, because glucosamine may be made from crustacean shells, those who are allergic to seafood should consult their doctor before taking it. People taking blood-thinning medicines, such as warfarin, should also talk to their doctor before taking glucosamine, as it may increase the risk of bleeding.
Glucosamine may also cause gastrointestinal upsets, sleepiness, headaches or skin reactions in some people.
People taking blood-thinning medicines, such as warfarin, should also be careful if taking chondroitin, as it may increase the risk of bleeding. Chondroitin may also occasionally cause stomach upset.
It is important that you check with your doctor before using dietary supplements as they may interact with other medicines you may be taking.
In Australia both glucosamine and chondroitin are classed as complementary medicines and are available as over-the-counter supplements. In some countries a prescription is needed for these products.
Products containing chondroitin and glucosamine products come under the ‘listed’ category on the Australian Register of Therapeutic Goods. This means that they are considered ‘lower risk’ ingredients and do not have to be tested with regard to effectiveness. Certain restrictions apply, however. For example, chondroitin can only be used as a component in other products and is not listable in its own right. If it is derived from cow, deer, goat or sheep originating in countries where BSE (bovine spongiform encephalitis) is present, special permission is needed from the Australian Therapeutic Goods Administration.
In addition, listed ingredients must comply with the Therapeutic Goods Advertising Code.
Last Reviewed: 31 March 2010