Studies of MSM have suggested some benefits, particularly for treatment of osteoarthritis.
Methylsulfonylmethane (MSM) is an organosulfur compound with the formula (CH3)2SO2. It is also known by several other names including DMSO2, methyl sulfone, and dimethyl sulfone. This colorless solid features the sulfonyl functional group and is considered relatively inert chemically. It occurs naturally in some primitive plants and is present in small amounts in many foods and beverages and it is marketed as a dietary supplement.
Evidence from clinical trials
Small-scale studies of possible treatments with MSM have been conducted on both animals and humans. These studies of MSM have suggested some benefits, particularly for treatment of osteoarthritis.
A review by S. Brien, P. Prescott, N. Bashir, H. Lewith and G. Lewith of the two small randomized controlled trials of methylsulfonylmethane in osteoarthritis knee pain relief “reported significant improvement in pain outcomes in the treatment group compared to comparator treatments; however, methodological issues and concerns over optimal dosage and treatment period were highlighted.”
The two trials included only 168 people, of whom 52 actually received the drug, so the review authors are careful to state: “No definitive conclusion can currently be drawn” and there is no “definitive evidence that MSM is superior to placebo in the treatment of mild to moderate osteoarthritis of the knee.” While one of the two studies suggests that taking MSM for 12 weeks or less may be safe, “further research is needed to assess its safety for long-term use.” Side effects of MSM ingestion include stomach upset, diarrhoea and headache. In the absence of studies into dosage, longer-term safety and definitive efficacy trials, MSM must be considered experimental and should not be self-administered or prescribed outside clinical trials.
After several reports that MSM helped arthritis in animal models, one study by P.R. Usha et al. had suggested that 1.5 g per day MSM (alone or in combination with glucosamine sulfate) was helpful in relieving symptoms of knee osteoarthritis. The Usha clinical trial, however, was outsourced to India and conducted by researchers with little prior experience in clinical trials; tests were described without associated data, while some results were unsupported by the data that was shown. K.S. Jayaraman has warned that such outsourcing of clinical trials can be “rash” and “risky,” citing deficient ethics committees as well as an unethical approach to patient recruitment.
Kim et al. conducted a second clinical trial of MSM for treatment of patients with osteoarthritis of the knee. Twenty-five patients took 6 g/day MSM and 25 patients took a placebo for 12 weeks. Ten patients did not complete the study, and intention to treat analysis was performed. Patients who took MSM reported reduced pain and improved physical function, but no evidence was found of a more general anti-inflammatory effect; there were no significant changes in two measures of systemic inflammation: C-reactive protein level and erythrocyte sedimentation rate. Not counting an unpublished, no-control group trial by Lawrence, these two articles are the only clinical-trial support for MSM for osteoarthritis.