From the Manufacturer:
The MSM Story-One of Nature's Primary Sources of Organic Dietary Sulfur!
The human body requires a continuous supply of usable sulfur, and MSM is one of the primary organic sulfur-containing molecules for use by living organisms. From life's earliest beginnings, primitive marine organisms (blue-green algae and phytoplankton) have absorbed inorganic sulfur from ocean waters and produced organic sulfur molecules, primarily dimethyl sulfonium salts. These salts are released back into the sea, where they are converted to dimethyl sulfide, which readily evaporates, ending up in the upper atmosphere. Dimethyl sulfide is then oxidized by UV light, forming DMSO and MSM. The two compounds are delivered to land masses in rain water, and absorbed by plants. MSM is a stable end-product of this process, and thus serves as a primary source of sulfur in the food chain.