Collagen is a substance secreted by the cells of the connective tissue (connective tissue cells), which is the primary protein of the skin. Serves as the coordinator of the skin tissue together. By this protein contains about 25% to 35% of the total protein in the body. With most of the skin and about 1% to 2% of the campsites in the muscle cells. Production of gelatin in the food of the process. Collagen digestion units called Hydrolysis.