What is glucosamine?
Glucosamine is made in the body from glucose (sugar) and glutamine (an amino acid). It is incorporated into proteins (proteoglycans) that contain long chains of sugar molecules and are highly concentrated in the spaces between cells including the joints, and has a strong ability to attract water. The body uses glucosamine to produce chemicals that are involved in building cartilage, tendons, ligaments and joint fluid, and as we age the amount produced declines.
Glucosamine supplementation has grown in popularity with athletes who are looking for relief from painful joints, preservation of joint integrity in the midst of heavy training and reduced risk of osteoarthritis (OA) particularly after sustaining a joint injury.
How might Glucosamine help with osteoarthritis and joint pain?
OA is thought to be caused by the breakdown of cartilage which cushions the ends of bones. When cartilage is worn down, it can expose the ends of the bones resulting in friction and joint pain with characteristic bony growths that can develop around the edge of the joint. This can occur in any joint and in athletes is more likely to occur in the knee.
OA is a progressive disease that usually occurs after 50 years of age, is more common in women than men, and is associated with factors such as ageing, genetics, obesity and physical injury. Participation in sports that cause minimal impact has little if any effect on the risk of OA but in contrast, participation in high impact sports can increase the risk of injury induced joint degeneration (1). Current treatment methods include the use of anti-inflammatory medication.lucosamine may prevent the breakdown of cartilage through several mechanisms, it activates chondrocytes (specialised cells in cartilage) to produce more collagen which holds the cartilage tissue together. Glucosamine also attracts water into the cartilage (to maintain the 70% water content of cartilage) producing a gel-like sac providing cushioning and flexibility in the joint. Supplementation is thought to increase the effect of glucosamine in the body.
Current research findings
There has been a lot of research looking at the use of glucosamine supplements (often in conjunction with chondroitin; a component of human connective tissues that is found in cartilage and bone). The focus of investigation has been their effectiveness at increasing the cartilage and fluid surrounding the joints or helping to prevent the breakdown of connective tissue, and hence the role in relieving joint pain and protection against the development of OA.
Early trials using a traditional dosage of 1500mg per day have found that in those with OA, glucosamine has reduced pain and provided some functional improvement (2,3) as well as some structural modifying effects (4) although study design has been criticised in some of this research.
Relief from joint pain
One of the biggest and most reliable research projects to date was the Arthritis Intervention Trial, GAIT (5) which was a multi-centred study set up to eliminate the flaws of previous research and investigate whether the use of glucosamine and chondroitin supplementation, whether taken separately or together, was effective in treating knee pain associated with OA.
The first phase of the GAIT study concluded that for those with moderate to severe knee pain caused by OA, the combination of the two supplements did show significant pain relief (79% showed a 20% or more improvement in knee pain versus 54% in the group not receiving supplements). There was a lack of response in those with mild pain, leading the authors to suggest that that the combination of glucosamine and chondroitin may be useful for those with moderate to severe pain (something that would warrant further research).
Development of osteoarthritis (structure-modifying effects)
In a study looking at the effect of glucosamine supplementation on the degree of joint space narrowing (the narrowing of joint indicates worsening osteoarthritis) in the knee, the authors found that glucosamine was not effective at producing structural modifications after one year but after three had a small protective effect suggesting supplementation may help slowing down progression of the disease (6). Similar findings of reduced joint space narrowing in the knee joint of those with OA have also been found in a number of systematic reviews of clinical trials (7,8).
A similar finding was also observed from the second phase of the GAIT study (5) when using only glucosamine supplementation in those with milder OA of the knee (although no clinically important reduction in structural damage was observed after 2 years supplementation with glucosamine and chondriotin when compared to the placebo group). The authors of this study suggested that those with less severe progression of OA may have the greatest benefits with glucosamine but further research would be required.
In a study by Bruyere and colleagues (9) researching the incidence of total knee joint replacement in those with knee OA, after receiving glucosamine or a placebo during a five year follow up. They found that glucosamine (1,500 mg/day) taken for at least 12 months reduced by half the incidence of this surgery within the group.
Although not recommended by NICE (National Institute of Clinical Excellence) in the UK, glucosamine supplementation is still widespread and many studies show promising results for its use in the management of OA.
Further good quality clinical trials investigating the use of glucosamine as a therapeutic treatment for joint health are required, but as it is considered ‘safe’ to use, it could be an alternative option to explore alongside conventional treatment.
Could glucosamine supplements benefit athletes?
Those who participate in high impact sports are at greater risk of joint injury, which is a risk factor for the development of OA. Based on the evidence to date (in ‘normal individuals’) it could indicate that glucosamine (and chondroitin) supplementation is useful for athletes suffering from moderate pain associated with OA, and could help athletes who have some ‘wear and tear’ of their joints, without suffering from OA.
Buckwater JA and Martin JA (2004). Sports and osteoarthritis. Current Opinion in Rhuematol. Sep; 16 (5): 634-9
McAlindon TE, LaValley MP, Gulin JP, Felson DT. Glucosamine and chondroitin for treatment of osteoarthritis: a systematic quality assessment and meta-analysis. JAMA. 2000;283:1469–1475.
Towheed TE, Maxwell L, Anastassiades TP, Shea B, Houpt J, Robinson V, Hochberg MC, Wells G. Glucosamine therapy for treating osteoarthritis. Cochrane Database Syst Rev. 2005
Pavelka K, Gatterova J, Olejarova M, Machacek S, Giacovelli G, Rovati LC. Glucosamine sulfate use and delay of progression of knee osteoarthritis: a 3-year, randomized, placebo-controlled, double-blind study. Arch Intern Med. 2002
Sawitzke AD, Shi H, Finco MF, Dunlop DD, Bingham CO 3rd, Harris CL, Singer NG, Bradley JD, Silver D, Jackson CG, Lane NE, Oddis CV, Wolfe F, Lisse J, Furst DE, Reda DJ, Moskowitz RW, Willaims HJ, Clegg DO (2008).The effect of glucosamine and/or chondroitin sulfate progression of knee osteoarthritis: a report from the glucosamine/chondroitin arthritis intervention trial. Arthritis Rheumatism Journal; 58 (10):3183-3191
Lee Y, Woo J-H, Choi S, Ji J, Song G. Effect of glucosamine or chondroitin sulfate on the osteoarthritis progression: a meta-analysis. Rheumatol Int. 2010;30:357–363. doi: 10.1007/s00296-009-0969-5.
Reginster JY, Deroisy R, Rovati LC, Lee RL, Lejeune E, Bruyere O, Giacovelli G, Henrotin Y, Dacre JE, Gossett C (2001). Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet ;357:251–256
Pavelka K, Gatterova J, Olejarova M, Machacek S, Giacovelli G, Rovati LC (2002). Glucosamine sulfate use and delay of progression of knee osteoarthritis: a 3-year, randomized, placebo-controlled, double-blind study. Arch Intern Med ;162:2113–2123
Bruyere O, Pavelka K, Rovati LC, Gatterova J, Giacovelli G, Olejarova M, Deroisy R, Reginster JY. Total joint replacement after glucosamine sulphate treatment in knee osteoarthritis: results of a mean 8-year observation of patients from two previous 3-year, randomised, placebo-controlled trials. Osteoarthritis Cartilage. 2008;16:254–260.