Organic sulfur is a general term that describes a variety of naturally occurring organic sulfur compounds. It includes MSM. MSM is a white or yellow crystalline solid that is insoluble in water. It is a strong organic base and is derived from the amino acid cysteine. MSM is a naturally occurring organic compound that contains sulfur. It is sold as a dietary supplement, often in the form of a liquid. It is also sold as a food additive and is used in cosmetics.