MSM (Methyl Sulfone or Dimethylsulfone) is an organic sulfur compound that is found naturally in some fruits, vegetables, cow's milk and meat. It is closely related to DMSO. It consists of two hydrocarbon units attached to one unit of sulfur and two oxygen atoms. Hence, it is one-third sulfur by weight. Sulfur is vital to the growth of hair, nails, organs and connective tissue, and is necessary for the production of insulin and the metabolism of carbohydrates.