est MSM and Best MSM Powder contain pure MSM (methylsulfonylmethane), a white crystalline substance that occurs in the human body and in some foods. MSM is an excellent dietary source of bioavailable organic sulfur. 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. Though present on earth since before life appeared on dry land, and known to science since the 1950's, MSM has only recently been recognized as having importance in human nutrition. Why the Human Body Needs MSM MSM occurs naturally in the blood, body fluids and tissues. It is now believed that a minimum MSM concentration of 0.2 parts per million is necessary for the body to function normally. MSM may be the most easily absorbed and non-toxic source of nutritional sulfur occurring in nature. Sulfur is a structural mineral that maintains the strength of various tissues by forming sulfur "tie-bars" (sulfhydryl bonds) between connective tissue proteins. MSM serves as a readily available source of sulfur for this function, and thus Enhances maintain the pliancy of tissues and cell membranes. Repair of damaged tissue depends upon a supply of sulfur for continuation of reactions involving sulfhydryl groups (-SH). Sulfur is required for the maintenance of healthy hair, skin and nails. In view of the presence of MSM in biological systems since the beginning of evolution, it is logical to assume that all higher life forms, including humans and animals, are well adapted to use MSM as a sulfur donor.