With Undenatured Type II Collagen Plus Hyaluronic Acid, Boron, Vitamin D-3 Promote optimal joint health and mobility with Advanced UC-II Joint Relief, featuring UC-II , a unique form of collagen with undenatured type II collagen. * Undenatured type II collagen is the principal ...With Undenatured Type II Collagen Plus Hyaluronic Acid, Boron, Vitamin D-3 Promote optimal joint health and mobility with Advanced UC-II Joint Relief, featuring UC-II , a unique form of collagen with undenatured type II collagen. * Undenatured type II collagen is the principal structural protein in cartilage that gives it tensile strength and toughness.