MSM serves as an important source of bioavailable dietary sulfur, a mineral that plays a critical role in maintaining the integrity and elasticity of connective and other tissues. It is an important component of proteins found throughout the body, such as in hair, nails, skin and tendons. MSM is a naturally occurring form of organic sulfur found mainly in protein-rich foods such as eggs, fish and lean meat. Taking MSM each day helps to replenish the body's supply of sulfur.