With Undenatured Type II Collagen Promotes Healthy Joint Comfort and Function Cartilage is one of the primary connective tissues of the body, providing flexibility and support to joints. Undenatured Type II Collagen is the principal structural protein in cartilage that is responsible for its tensile strength and toughness. Derived from chicken sternum cartilage, UC-II is a patented form of Undenatured (native) Type II Collagen that works with the immune system to support healthy joints. Human clinical studies have found that just one 40 mg capsule of UC-II per day can help to promote joint comfort, as well as healthy joint function and flexibility.