Doctor?s Best Synergistic Glucosamine/ MSM Formula supplies several building blocks for healthy joints. Glucosamine sulfate supports joint structure and function and supplies healthy joints with proteoglycans which contribute to healthy joints and connective tissues.* Methylsulfonylmethane (MSM from OptiMSM*) supplies bioavailable sulfur needed for joints.* OptiMSM* ins purified via distillation for highest purity and consistency and is an excellent source of sulfur.* Vitamin C is essential for the production of collagen a structural protein.* At Doctor?s Best we lead with science. Our products are backed by research and crafted using pure ingredients carefully sourced from around the globe. Since 1990 we have dedicated ourselves to providing highly effective nutritional supplements that enable you to live a healthier lifestyle. We want nothing more than to see you and your family thrive!