MSM (methyl sulfonyl methane) is a sulfur-containing compound normally found in many of the foods we eat. It is chemically related to DMSO (dimethyl sulfoxide), a popular (although unproven) treatment for arthritis. When DMSO is applied on the skin or taken orally, about 15% of it breaks down in the body to form MSM.1

Some researchers have suggested that the resulting MSM could be responsible for the benefits attributed to DMSO. If so, MSM might be preferable as a treatment, because it does not cause some of the unpleasant side effects associated with DMSO treatment, such as body odor and bad breath. In addition, as a natural substance found in food, MSM would be expected to have a good safety profile. However, there is as yet no more than preliminary evidence that MSM is useful for any medical condition.

There is no dietary requirement for MSM. However, it occurs naturally in cow's milk, meat, seafood, vegetables, fruits, and even coffee, tea, and chocolate. MSM supplements are sold in healthfood stores and some pharmacies. Although creams and lotions containing MSM are also available, it is hard to see the purpose of these topical products since MSM, unlike DMSO, is not absorbed through the skin.2

MSM supplies sulfur. Some advertisements for MSM claim that sulfur deficiency is widespread, and that for this reason alone MSM will improve the health of most everybody who takes it. However, there are numerous other dietary sources of sulfur, including, most prominently, many forms of ordinary protein.