Vitamin B12 (cyanocobalamin): functions, hypovitaminosis, norm and food Vitamin B12 is a complex organic compound that contains: carbon, hydrogen, cobalt, nitrogen, oxygen and phosphorus. Cyanocobalamin is a water-soluble vitamin that is based on the structure of a corrinoid, in the center of which is a cobalt ion. There are other similar chemicals in nature, such as hemoglobin (which has iron in its center) and chlorophyll (which has magnesium in its center). In the body, cyanocobalamin works b