Overview. Vitamin B12, also called cobalamin, is one of 8 B vitamins. All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy.These B vitamins, often referred to as B complex vitamins, also help the body use fats and protein.B complex vitamins are needed for healthy skin, hair, eyes, and liver.ll B vitamins are water soluble, meaning that the body does not store them. Vitamin B12 is an especially important vitamin for maintaining healthy nerve cells, and it helps in the production of DNA and RNA, the body's genetic material.