Doctor's Best brings you this Synergistic Glucosamine/MSM Formula that offers sodium-free, potassium stabilized glucosamine sulfate, making this premier joint support supplement suitable for most. OptiMSM is pure MSM (methylsulfonylmethane), a naturally occurring source of organic dietary sulfur that is readily absorbed and utilized by the body to meet its sulfur needs. Glucosamine is used to support normal, healthy joint function and helps maintain healthy cartilage in your joints. MSM supports organ and joint function by donating sulfur for maintaining healthy connective tissue. Vitamin C is also included in this formula to promote the normal production of collagen, a protein that gives strength to cartilage.