S. Phoon and N. Manolios
Article used with permission.Abstract
Glucosamine is a modified sugar that is formed by the human body and used as a precursor to form larger molecules called glycosaminoglycans, which are involved in the formation and repair of cartilage. These repeating sugar units are also a major constituent of bones, ligaments, tendons and fluid in the joint. Because of their low compressibility they are ideal lubricants and are used as shock absorbers by joints. It is believed that synthetically produced and ingested glucosamine may be beneficial in correcting the imbalance between production and destruction of naturally occurring glucosamine in osteoarthritis cartilage, thereby repairing damaged joints.There are a multitude of brands available over the counter. There are two chemical forms available, glucosamine sulfate (Arthro-Aid Direct, Bioglan, Blackmores, Arthrogen, GoldenGlow, Healthstream and Procosamine); and glucosamine hydrochloride (Arthro-Aid and Osteo-Eze). Glucosamine has been administered in a variety of ways, such as a topical cream, an oral tablet, an intra-muscular injection and as an intra-articular injection (that is directly into the joint). Both types of glucosamine tablets are supplied in doses of 400 to 1000mg. The recommended dose of glucosamine is 1 to 2 tablets per day. In research studies the dose most commonly tested has been 1500mg per day. After taking a tablet of glucosamine, the concentration peaks in the blood stream at 4 hours, and slowly declines over 24 hours. When radioactively labeled forms of glucosamine were used in experiments, it was shown to be actively taken up in skeletal tissue such as cartilage and bone. It was also noted to be found in other tissues, particularly liver and kidney, although its role in these organs is less clear.Osteoarthritis or degenerative joint disease is the most common type of arthritis. It usually affects middle-aged and elderly people, and is characterized by the breakdown of cartilage. Cartilage is responsible for providing the “shock-absorption” at the end of bones, and it is the loss of this cushioning effect due to the loss of glycosaminoglycans that results in pain and decreased range of motion. Osteoarthritis may be diagnosed by clinical examination or by X-rays. Until now, the focus of treatment has revolved around medication to relieve symptoms such as pain and the protection of the joint. These have included aspirin, paracetamol and non-steroidal anti-inflammatory drugs (NSAIDS). The major concern with NSAIDS is the risk of upper gastro-intestinal side effects, particularly bleeding stomach ulcers.There are a large number of studies using glucosamine that have been reported to show a symptomatic improvement in flexibility. Pooling all of these studies together, researchers have used a technique called meta-analysis to combine similar well-designed studies to determine whether or not there is a real effect. This is particularly useful in combining many small studies with smaller numbers of patients. All 3 meta-analyses have reported an improvement with glucosamine for the easing of joint discomfort using various measures of pain 9-12.