Methylsulfonylmethane (MSM) is a naturally occurring, organic, sulfur-containing compound related to another sulfur-containing substance, dimethyl sulfoxide (DMSO). MSM is found in small amounts throughout nature and has been detected in small amounts in the blood and urine of humans.
A precursor of MSM is formed initially by ocean plankton and released into the atmosphere, where it interacts with ozone and sunlight and returns to earth as MSM in rainfall. MSM can be taken up by plants and incorporated into their structure, but no measurement of the MSM content of foods has been done. Supplements containing MSM are available.
Although MSM is present in food, it is not an essential nutrient, so deficiency is not likely.
Osteoarthritis
According to some anecdotal reports, MSM has been used in human research for many years in amounts above 2000 mg per day with no significant adverse effects. However, diarrhea, skin rash, headache, and fatigue may be experienced in less than 20% of people, according to other anecdotal reports. Detectable levels of MSM in the brain of a person taking MSM supplements have been reported, but the significance of this finding, if any, is unclear. At the time of writing, there were no well-known drug interactions with methylsulfonylmethane.
Some authorities report anecdotally that 250–500 mg per day has beneficial effects on a variety of health problems. However, the only controlled trial using MSM used over 2000 mg per day to treat osteoarthritis. More research is needed before reliable recommendations for MSM supplementation can be made.