Sandoz Joint Wellness Pack 3 x 30 capsules Collagen is composed of a wide variety of subtypes (I to XIII), but it is the undenatured or non-hydrolyzed type II collagen that is present in articular cartilage. Its main functions are to resist intermittent pressure and support the joints. Vitamin C contributes to the normal formation of collagen for the normal functioning of skin, bones, blood vessels and cartilage. Vitamin D contributes to maintaining bone health and the absorption and use of calcium and phosphorus.