Vitamin B12 plays a vital role in brain function and the production of DNA and red blood cells. B12 is only found naturally in animal foods, therefore this injection is highly recommended and beneficial for people following a vegetarian or vegan diet. Cyanocobalamin is a man-made form of vitamin B12 used to treat low levels (deficiency) of this vitamin. Vitamin B12 helps your body use fat and carbohydrates for energy and make new protein. It is also important for normal blood , cells, and nerves.