What does the evidence say about glucosamine sulphate and chondroitin and arthritis? Gillian Rowe investigates
Both glucosamine and chondroitin are substances that occur naturally in the body. Glucosamine is a natural sugar made from the simple carbohydrate glucose and the amino acid glutamine. It is produced in the body to provide natural building blocks for growth, repair and maintenance of cartilage, the smooth tissue that lines the joints and helps to give it its elastic buffering properties. Chondroitin is a molecule and makes up a component of human connective tissues found in cartilage and bone and helps retain water.
For many years, people have been taking glucosamine and chondroitin as a combination supplement to treat osteoarthritis pain and help to ease the symptoms of their stiff joints. Chondroitin sulphate is manufactured from the cartilage of animals, or it can be made synthetically in a laboratory. For dietary supplements, glucosamine is derived from shells or shellfish, such as shrimps, lobsters and crabs), vegetable sources, or it can also be made in a laboratory.
There have been a number of trials looking into the effectiveness of taking a combination of glucosamine and chondroitin sulphate in treating osteoarthritis. Findings have been mixed, with some evidence supporting the use of glucosamine sulphate to treat knee osteoarthritis better than other joints. In a 2005 review of 20 glucosamine studies, an improvement was found in joint pain, stiffness and function with one brand of glucosamine (Rottopharm, marketed as Dona, Viartril and Xicil) but not others. The Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), conducted in 2008, was a large randomised placebo-controlled trial involving 1,600 people with knee osteoarthritis at various sites across the US. Researchers investigated whether glucosamine and/or chondroitin could treat the pain of knee osteoarthritis and an ancillary study investigated whether these dietary supplements could diminish the structural damage of knee osteoarthritis.
The ancillary study results, published in Arthritis & Rheumatism, showed that glucosamine and chondroitin sulphate, together or alone, appeared to fare no better than a placebo in slowing loss of cartilage in knee osteoarthritis. However, it was found that interpreting the results was complicated, because participants taking a placebo had a smaller loss of cartilage, or joint space width, than predicted. A new study in 2013, however, led by Prof Johanne Martel-Pelletier of the osteoarthritis research unit at the University of Montreal Hospital Research Centre in Canada, underlined the potential benefits of glucosamine and chondroitin supplements for osteoarthritis, compared with traditional treatment options. For the study, a total of 600 patients with knee osteoarthritis were divided up, based on whether they received conventional pharmacological treatment and/or glucosamine/ chondroitin sulphate over a 24-month period and were assessed for knee structural changes using quantitative magnetic resonance imaging (qMRI). The study, published in the Annals of the Rheumatic Diseases, found that patients taking glucosamine and chondroitin sulphate experienced a reduction in cartilage volume loss over the two-year period.
These benefits were seen regardless of whether the patients were also receiving more conventional treatment using analgesic therapies or NSAIDs. The study said that many of the benefits were not picked up on X-rays, but could only be demonstrated by using qMRI.
When it comes to the benefits of glucosamine and chondroitin in rheumatoid arthritis, the evidence is much less clear. Although chondroitin sulphate has been shown to inhibit enzymes in synovial fluid that are linked to destruction of cartilage in rheumatic disease, there is a lack of evidence to support glucosamine use for rheumatoid arthritis and experts believe more research is needed in this area.
Can there be any negative side effects?
Over-the-counter glucosamine and chondroitin come with next to no warnings of any side effects, and they are considered to be usually mild and infrequent. These include: Stomach upsets;
If you are allergic to shellfish, you should make sure that you take the shellfish-free variety. And for those who suffer from diabetes, glucosamine may increase your blood sugar levels, so discuss with your doctor before taking them. There are also some reports of possible interaction with chemotherapy drugs and drugs that lower blood cholesterol.
Can I get it in my diet?
Although edible seafood such as shrimps, lobsters and crabs can provide trace amounts of glucosamine in their shells, these can be difficult to chew and digest and are not commonly used in dishes. Glucosamine occurs naturally in all forms of healthy cartilage, and while the parts of animals that we no longer eat, such as snouts and joint tissues, are fashionable in some city restaurants, you probably won’t want to eat cartilaginous offal other than to flavour a stew.