Doctor's Best Glucosamine Chondroitin Msm + Hyaluronic Acid provides four important nutrients which help maintain joints: glucosamine, chondroitin, Methylsulfonylmethane (MSM, from OptiMSM), and Hyaluronic Acid (from BioCell Collagen). Glucosamine supports joint mobility. Cartilage, composed of proteoglycans, is mainly located on bones and near joints, and consists primarily of collagen protein with side chains called chondroitin sulfate. MSM supplies bioavailable sulfur needed for joint health. BioCell Collagen is a proven dietary ingredient that contains a patented composition of naturally occurring hydrolyzed collagen type Ii, chondroitin sulfate, and hyaluronic acid in a highly absorbable matrix.