MSM

MSM is an organosulfur compound with the formula (CH3)2SO2 and is the simplest member of the sulfone family; its other common name is dimethyl sulfone, or DMSO2. It occurs naturally in some plants and in small amounts in a range of foods and beverages, and it can be produced by oxidizing dimethyl sulfoxide (DMSO), to which it is closely related. Because it is thermally stable and polar, molten MSM also has industrial use as a solvent.

As a supplement, MSM is marketed for anti-inflammatory and pain-relieving effects, for joint and skin health, and for general well-being, but no medical use for it has been formally approved. Much of the human research has focused on osteoarthritis of the knee. A randomized, placebo-controlled pilot trial found that MSM significantly reduced knee pain and improved physical function over twelve weeks ^[1]. A systematic review of MSM and the related compound DMSO in osteoarthritis concluded that the better-designed MSM trials offer positive but not definitive evidence of benefit, while flagging concerns about dosing, treatment length, and study quality ^[2]. A more recent randomized trial reported improvements in knee-related quality of life among people with mild knee pain ^[3]. MSM has also been examined for oxidative stress during exercise and for seasonal allergy symptoms, again with limited data.

MSM has a strong safety record in animal studies, with toxicity appearing only at very high doses, and a branded form received generally recognized as safe (GRAS) status in the United States in 2008. It is sold as an oral supplement, often in combination with glucosamine and chondroitin, rather than as a licensed medicine.

MSM is very well tolerated, with occasional mild GI upset, headache, or bloating. It has a strong safety record even at gram-level doses. Long-term data is limited but no serious concerns have emerged.