What is it?
Glucosamine is an important building block needed by the body to manufacture specialized molecules called glycosaminoglycans, found in cartilage.
Where is it found?
Glucosamine is not present in significant amounts in most diets. Supplemental sources are derived from the shells of shrimp, lobster, and crab, or may be synthesized.
What do the advocates say?*
For a long time, glucosamine dominated the market among supplements used to ease joint pain. Now, many practitioners prefer to use a combination of both glucosamine and chondroitin sulfate. Many have found this combination to be effective, particularly for runners, who tend to develop problems with their knees. Glucosamine and chondroitin sulfate are well absorbed by the molecules that make up cartilage. They are not available from food. It is not uncommon to have to take these supplements indefinitely to continue to experience relief.
Recent research has shown that the results of arthroscopic surgery for osteoarthritis in the knee is no different than that of placebo. This gives people further reason to at least give supplements, such as glucosamine sulfate, a try before enduring more invasive, expensive approaches.
How much is usually taken by athletes?
Glucosamine sulfate, 1,500 mg per day, is effective for reducing joint pain caused by osteoarthritis according to most studies,1 2 3 Whether other forms of glucosamine, such as glucosamine hydrochloride, are as effective for joint pain as glucosamine sulfate is unclear at this time, but studies have found some benefits from the use of the hydrochloride form.4 5 Other uses of glucosamine for sports and fitness, including prevention of joint pain or treatment of sports injuries, have not been studied.
Are there any side effects or interactions?
At the amount most frequently taken by adults—500 mg three times per day of GS—adverse effects have been limited to mild reversible gastrointestinal side effects. In one trial, people with peptic ulcers and those taking diuretic drugs were more likely to experience side effects.6
Animal research has raised the possibility that glucosamine could contribute to insulin resistance.7 8 This effect might theoretically result from the ability of glucosamine to interfere with an enzyme needed to regulate blood sugar levels.9 However, available evidence does not suggest that taking glucosamine supplements will trigger or aggravate insulin resistance or high blood sugar.10 Two large, 3-year controlled trials found that people taking GS had either slightly lower blood glucose levels or no change in blood sugar levels, compared with people taking placebo.11 12 Until more is known, people taking glucosamine supplements for long periods may wish to have their blood sugar levels checked; people with diabetes should consult with a doctor before taking glucosamine and should have blood sugar levels monitored if they are taking glucosamine.
In 1999 the first case of an allergic reaction to oral GS was reported.13 Allergic reactions to this supplement appear to be rare.
Some GS is processed with sodium chloride (table salt), which is restricted in some diets (particularly for people with high blood pressure).
The theory that GS and chondroitin sulfate work synergistically in the treatment of osteoarthritis remains unproven.
*Athletes and fitness advocates may claim benefits for glucosamine based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on glucosamine. For more complete and detailed information, including references and safety information, see Glucosamine as a nutritional supplement.
References
1. Reginster JY, Deroisy R, Rovati L, et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet 2001;357:251–6.
2. Pavelka K, Gatterova J, Olejarova M, et al. Glucosamine sulfate use and delay of progression of knee osteoarthritis: a 3-year, randomized, placebo-controlled, double-blind study. Arch Intern Med 2002;162:2113–23.
3. McAlindon TE, LaValley MP, Gulin JP, Felson DT. Glucosamine and chondroitin for treatment of osteoarthritis: a systematic quality assessment and meta-analysis. JAMA 2000;283:1469–75 [review].
4. Houpt JB, McMillan R, Wein C, Paget-Dellio SD. Effect of glucosamine hydrochloride in the treatment of pain of osteoarthritis of the knee. J Rheumatol 1999;26:2423–30.
5. Braham R, Dawson B, Goodman C. The effect of glucosamine supplementation on people experiencing regular knee pain. Br J Sports Med 2003;37:45–9.
6. Tapadinhas MJ, Rivera IC, Bignamini AA. Oral glucoseamine sulfate in the management of arthrosis: report on a multi-centre open investigation in Portugal. Pharmatherapeutica 1982;3:157–68.
7. Virkamaki A, Daniels MC, Hamalainen S, et al. Activation of the hexosamine pathway by glucosamine in vivo induces insulin resistance in multiple insulin sensitive tissues. Endocrinology 1997;138:2501–7.
8. Rossetti L, Hawkins M, Chen W, et al. In vivo glucosamine infusion induces insulin resistance in normoglycemic but not in hyperglycemic conscious rats. J Clin Invest 1995;96:132–40.
9. Barzilai N, Hawkins M, Angelov I, et al. Glucosamine-induced inhibition of liver glucokinase impairs the ability of hyperglycemia to suppress endogenous glucose production. Diabetes 1996;45:1329–35.
10. Russell AI, McCarty MF. Glucosamine in osteoarthritis. Lancet 1999;354:1641; discussion 1641–2 [letters].
11. Rovati LC, Annefeld M, Giacovelli G, et al. Glucosamine in osteoarthritis. Lancet 1999;354:1640; discussion 1641–2.
12. Reginster JY, Deroisy R, Rovati L, et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet 2001;357:251–6.
13. Matheu V, Bracia Bara MT, Pelta R, et al. Immediate-hypersensitivity reaction to glucosamine sulfate. Allergy 1999;54:643–50.
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2006-09-07
