Collagen: The main supporting fiber located within the dermis, gives strength and provides structure to the skin. Topical collagen is able to moisturize and hydrate by holding many times its own weight in water. Collagen is a natural substance within body tissues. It is a protein that serves as the support structure for the skin and all other connective tissues. In human skin, collagen fibers comprise more than 70% of the dry weight of the dermis. As we age, our own soluble collagen becomes less flexible and our skin's connective tissue loses its ability to retain moisture naturally.