Glucosamine, an over-the-counter alternative treatment for arthritis, is one of the most popular supplements sold in the United States. According to a 2008 article in "American Family Physician," it is also one of the most studied. Despite a great deal of research, glucosamine's effectiveness remains controversial, so you should consult your physician to see if this supplement is appropriate for you.
Glucosamine Normally Found in Joints
Chemically, glucosamine resembles both a sugar and a protein. It is synthesized in your body from glucose and the amino acid glutamine and used as a building block for connective tissues, such as ligaments and tendons. The highest concentrations of glucosamine are found in the cartilage surrounding your joints.
How Glucosamine Works
The basis for glucosamine's purported benefits is unknown. Dr. Stephen Dahmer, an integrative family medicine fellow at Beth Israel Center for Health and Healing, hypothesizes that glucosamine might directly stimulate the chondrocytes, which are cells that build and support cartilage in your joints. Other potential mechanisms of action include incorporation of important sulfur molecules into cartilage, down-regulation of genes that promote the degeneration of cartilage or replacement of critical joint constituents, such as keratan sulfate or hyaluronic acid.
Clinical Uses
Glucosamine's effects have been studied in temporomandibular joint disorders, rheumatoid arthritis, spinal arthritis and osteoarthritis, or OA, of the hip and knee. Most clinical trials have investigated its benefits in osteoarthritis of the knee, a condition that affects about 10 percent of people over the age of 60. However, results of clinical trials have been inconsistent, underscoring the need for patients to check with their doctors before taking glucosamine.
Inconsistent Benefit
A 1994 study cited in "Osteoarthritis and Cartilage" demonstrated that glucosamine sulfate was as effective as ibuprofen for controlling the symptoms of osteoarthritis. Another review in 2009 reported that glucosamine "shows some clinical effectiveness in the treatment of OA of the knee." However, the authors of the two-year Glucosamine/chondroitin Arthritis Intervention Trial, or GAIT, could not show that glucosamine conferred any significant benefit among patients with osteoarthritis. A 2010 review in "BMJ Clinical Research" concluded that glucosamine offered no benefit for arthritis of the hip or knee and argued against insurance coverage for glucosamine preparations. While the preponderance of evidence suggests some improvement among OA sufferers who take glucosamine, such improvement has generally been limited.
Side Effects
Glucosamine has demonstrated an excellent safety profile in clinical trials to date. Side effects, if any, are mild and include abdominal pain, heartburn, nausea and diarrhea. As of 2010, concerns that glucosamine interferes with the management of diabetes have recently been laid to rest. Although glucosamine is made from shellfish, the agents that cause allergies to shellfish are not present in glucosamine preparations. There is no information regarding the safety of glucosamine during pregnancy.
Considerations
Although no significant drug interactions have been reported with glucosamine, if you take other supplements or prescription medicines, you should approach the use of glucosamine with caution. While studies indicate that glucosamine sulfate may offer benefits, glucosamine hydrochloride probably does not. Given the inconsistencies in study outcomes and the relatively small magnitude of benefit conferred by glucosamine, people with severe arthritis or those with other medical concerns should first check with their doctors before taking glucosamine.
References
- "American Family Physician": Dietary supplements for osteoarthritis
- "American Family Physician": Complementary and Alternative Medicine: Glucosamine
- PubMed.gov: Glucosamine sulfate compared to ibuprofen in osteoarthritis of the knee
- PubMed.gov: The clinical effectiveness of glucosamine and chondroitin supplements in slowing or arresting the progression of osteoarthritis of the knee: a systematic review and economic evaluation
- "Annals of the Rheumatic Diseases": Clinical efficacy and safety of glucosamine, chondroitin sulfate, their combination, celecoxib or placebo taken to treat osteoarthritis of the knee: 2-year results from GAIT
- PubMed.gov Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis
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