Osteoarthritis (OA) is a condition characterized by joint degeneration and mobility loss especially in the knees. It is a prevalent condition in the population and is often acquired in one of two ways: quietly, through progressive changes to the joint and surrounding soft tissue over time, or through a traumatic event such as a fall or an accident.
In an effort to reduce the likelihood of incurring knee OA or to limit its progression, supplementation with Glucosamine and/or Chondroitin have been proposed.
What are Glucosamine and Chondroitin, and How Do They Work?
Glucosamine is a naturally occurring amino acid bound to a glucose molecule that is commonly derived from shellfish exoskeleton or it is chemically engineered. In North America, it is considered a dietary supplement and therefore is not federally regulated. Typically, dosages of 1500mg are recommended by manufacturing companies.
Upon ingestion, Glucosamine is proposed to work by being converted to molecules of proteoglycans, which help form cell walls and provide reinforcing strength.
Chondroitin is a very similar molecule, except it is derived from bovine cartilage. It is proposed to work on the body in very similar ways – essentially increasing the rate of cell wall production and strength. It is often prescribed in dosages of 800mg.
Although it is often advertised to consume both in combination, there is no evidence to suggest taking either one in isolation is any less effective.
Do They Work?
Most studies that show benefit to using Glucosamine or Chondroitin suggest that results are of relatively little magnitude. When they do exist, over a 2-5 year period, they can potentially preserve joint space in the knee, with marginal effect on pain and functional outcomes.
Because glucosamine is a glucose-based molecule, those with diabetes or with impaired glucose control should be cautious. It is not recommended for those with shellfish allergies if it derived from chitin, nor is it recommended for pregnant women. Skin rashes, peripheral edema, and gastrointestinal disturbances are potential side effects.
Should They Be Recommended?
From a scientific perspective, because of the prolonged use required to demonstrate marginal gains, together with the many holes in the scientific articles that support their consumption (small sample sizes, authors’ conflicts of interest and other methodological biases), at a cost of $15-30 per bottle, the recommendation of these products should be carefully considered.
By Slav Feldman,
BSc.Kin, Msc.PT, MClSc.MT
Registered Physiotherapist, FCAMPT
- Fransen M, Agaliotis M, Nairn L, Votrubec M, Bridgett L, Su S, et al. Glucosamine and chondroitin for knee osteoarthritis: a double-blind randomised placebo-controlled clinical trial evaluating single and combination regimens. Ann Rheum Dis [Internet]. 2014;1–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24395557
- Hochberg MC. Structure-modifying effects of chondroitin sulfate in knee osteoarthritis: an updated meta-analysis of randomized placebo-controlled trials of 2-year duration. Osteoarthr Cartil [Internet]. Elsevier Ltd; 2010;18(SUPPL. 1):S28–31. Available from: http://dx.doi.org/10.1016/j.joca.2010.02.016
- Reginster JY, Deroisy R, Rovati LC, Lee RL, Lejeune R, Bruyere O, et al. Long term effects of glucosamine sulphate on osteoarthritis progression: a randomized, placebo controlled clinical trial. Lancet. 2001;357(9252):251–6.
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- Towheed TE. Current status of glucosamine therapy in osteoarthritis. Arthritis Rheum [Internet]. 2003;49(4):601–4. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12910570
- Zeng C, Wei J, Li H, Wang Y, Xie D, Yang T, et al. Effectiveness and safety of Glucosamine, chondroitin, the two in combination, or celecoxib in the treatment of osteoarthritis of the knee. Sci Rep [Internet]. Nature Publishing Group; 2015;5(August):16827. Available from: http://www.nature.com/articles/srep16827