Glucosamine, chondroitin and methylsulfonylmethane (MSM) are three of the most commonly sold dietary supplement ingredients for osteoarthritis. Though not entirely consistent, evidence is present that each provides relief from osteoarthritis pain. As of mid-2010, no clinical trials have been published testing all three in combination. Therefore, evaluation of side effects of the combination must rely on reported side effects for each ingredient individually.
Insulin Resistance and Diabetes
In theory, because glucosamine contains a glucose molecule, concerns existed that glucosamine would contribute to the development of insulin resistance, and hence, diabetes. This has been discounted. In a clinical trial reported by Ranganath Muniyappa in the November 2006 issue of Diabetes, neither lean nor obese subjects had any worsening of insulin resistance after six weeks of glucosamine at 1500 mg per day. A safety review by James Anderson in the February 2005 issue of Food and Chemical Toxicology reported no increase in blood sugar in five clinical trials.
Headache
According to Stanley Jacobs, MD, in his book "The Miracle of MSM," some people starting MSM at amounts of 5000 mg per day reported having headaches. The MSM amount used in osteoarthritis products that combine glucosamine, chondroitin and MSM is less than 1000 mg. For glucosamine or chondroitin or the combination of the two, the incidence of headache was not different from placebo, as reported by Daniel Clegg in the February 2006 issue of the New England Journal of Medicine. The amounts used in this large clinical trial--1500 mg per day and 1200 mg per day, respectively--are the amounts most commonly sold in commercial products.
Gastrointestinal Distress
For glucosamine, James Anderson's safety review described gastrointestinal (GI) side effects as matching or less than those seen in the placebo control groups. A similar lack of GI side effects was reported by Daniel Uebelhart during a one-year trial of chondroitin, as reported in the April 2004 issue of Osteoarthritis and Cartilage. In the two published MSM clinical trials, first authors Dr. Linda Kim and Dr. P.R. Usha reported that GI side effects were similar to placebo without providing details.
Clinical Chemistry, Hematology and Urinalysis
In the March 2006 issue of Osteoarthritis and Cartilage, Dr. Linda Kim reported no differences between placebo and a dosage of 6000 mg per day of MSM for blood or urine tests, other than a slight decrease in blood homocysteine in the treated group--which might be considered beneficial for heart and brain health. James Anderson's safety review reported no differences from placebo for glucosamine. Daniel Clegg reported no differences for glucosamine, chondroitin or the combination of the two.
Special Populations
The great majority of the clinical trials of these ingredients were with adults that had osteoarthritis. Safety has not been evaluated in children, in pregnant or lactating women, or in patients with diseases or medications that could affect the metabolic disposition of glucosamine, chondroitin or MSM. It is always wise to confer with a physician before using a dietary supplement.
References
- "Diabetes": Oral glucosamine for 6 weeks at standard doses does not cause or worsen insulin resistance or endothelial dysfunction in lean or obese subjects
- "Food and Chemical Toxicology": Glucosamine effects in humans: a review of effects on glucose metabolism, side effects, safety considerations and efficacy
- "The New England Journal of Medicine": Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis
- "Osteoarthritis and Cartilage": Intermittent treatment of knee osteoarthritis with oral chondroitin sulfate: a one-year, randomized, double-blind, multicenter study versus placebo
- Osteoarthritis and Cartilage": Efficacy of methylsulfonylmethane (MSM) in osteoarthritis pain of the knee: a pilot clinical trial
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