MSM (Methylsulfonylmethane) is a sulfur-bearing compound that is naturally present in very small amounts in fruits, vegetables, grains, animal products, and some algae. Sulfur compounds are found in all body cells and are indispensable for life. MSM, in its role in the body's sulfur cycle, helps to create the chemical links needed to form and maintain numerous different types of structural tissues of the human body, including connective tissues, such as articular cartilage and skin.