Vitamin B12, molecular model. Vitamin B12 (cyanocobalamin) is an essential nutrient that humans are unable to produce and need to obtain from their diet. It is found in meat, fish poultry and dairy products. Vitamin B12 is needed for producing red blood cells and for a healthy nervous system. Deficiency can lead to pernicious anaemia, with symptoms including tiredness, dizziness and a reduced sense of taste. Vitamin B12's chemical formula is C63H88CoN14O14P. Atoms are represented as spheres and are colour-coded: carbon (C, grey), hydrogen (H, turquoise), cobalt (Co, pink), nitrogen (N, blue), oxygen (O, red) and phosphorus (P, green).