Doctor's Best MSM with OptiMSM contains a high quality purified MSM (methylsulfonylmethane) backed by numerous clinical studies for safety and efficacy. MSM is a natural sulfur compound that helps support the formation of healthy connective tissues. It also helps support overall joint health, mobility, and a normal range of motion. It also may help reduce oxidative damage to support a healthy immune system. MSM provides the sulfur reputable for being nature's 'beauty mineral'. Sulfur is a key component of collagen that supports the skin's structural framework and is also a building block of keratin, a structural constituent of hair and nails.