Choose glucosamine products wisely
DOES IT WORK?Glucosamine and osteoarthritis.
GLUCOSAMINE IS commonly used to treat arthritic pain and stiffness. Osteoarthritis is the most common form of arthritis throughout the world. It causes much of the muscle and joint pain that afflicts the elderly, and can lead to significant difficulties in walking and other daily activities.
Many different approaches can help osteoarthritis, including exercise, weight-loss, physiotherapy and various medications. Since 2000, at least 800 new dietary supplement products have been introduced targeted at osteoarthritis.
Some have evidence that they work and are safe; most do not. Glucosamine is one of the most popular of these. A Euromonitor International report on health and wellness products in Ireland found that glucosamine was the dietary supplement with the greatest per cent increase in sales over recent years.
Glucosamine is a natural substance required to make important compounds found in cartilage, ligaments and synovial fluid (in the knee). Since osteoarthritis involves the breakdown of cartilage, glucosamine was predicted to help overcome that damage.
Glucosamine can be obtained from the skeletons of shellfish or manufactured chemically. It is available as glucosamine sulphate or glucosamine hydrochloride. Products often combine glucosamine with other supplements, most commonly chondroitin or manganese.
The evidence regarding chondroitin will be examined here next week.
Evidence from studies
A relatively large number of studies have examined glucosamine for osteoarthritis, mostly in the knee or hip. These are the joints most commonly affected.
Overall, the results do suggest some benefits, but the results have not been completely consistent. Improvements in walking and daily activities were more consistent than impact on pain. However, some studies have found that glucosamine is as effective as other pain relievers. Two studies also found that osteoarthritis patients taking glucosamine for three years had only half the joint deterioration compared with those taking placebo. If this result is confirmed in other research, glucosamine could be important in slowing down osteoarthritic damage.
Different formulations of glucosamine are commonly recommended. Glucosamine sulphate is consistently more beneficial than glucosamine hydrochloride. Many combination products have not been tested, and none of those tested have shown themselves to have any advantages over glucosamine sulphate alone.
Overall, glucosamine sulphate has had few adverse effects in clinical trials lasting up to three years. It commonly causes gastrointestinal problems such as nausea, heartburn and diarrhoea, but no more so than aspirin and other pain-relievers.
Concerns have arisen that glucosamine could interfere with normal sugar metabolism and lead to diabetic problems. However, most of the concerns arose due to animal studies, and humans appear to handle glucosamine differently.
Research in people with normal sugar metabolism and those with type 2 diabetes showed no negative changes in insulin or sugar levels when taking glucosamine.
People with allergies to shellfish have been concerned about taking glucosamine made from shellfish. However, most shellfish allergies are caused by the meat, not the shell. Allergic reactions to glucosamine have not been reported.
The Osteoarthritis Research Society International is an international, non-profit organisation dedicated to improving the treatment and prevention of osteoarthritis. In February its new guidelines noted that optimal management of osteoarthritis requires combining medications, when necessary, with non-pharmacological approaches.
These include exercise, weight-management and other lifestyle changes. When appropriate, a six-month trial of glucosamine sulphate is recommended for people with osteoarthritis of the knee. Other pain-relieving medications, such as acetaminophen or aspirin, may still be needed during flare-ups.
Many glucosamine products are available without prescription in Ireland. However, great variability exists in product doses and quality. The product with the most research support comes in 1500mg sachets and requires a prescription in Ireland.
Given the chronic nature of osteoarthritis, it is important to discuss all the medications you may be taking with your doctor, pharmacist or nurse.
Dónal O'Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University