Vitamin B12 is a water soluble B vitamin naturally found in fish, dairy produce, organ meats, beef, pork, nuts and seeds. Functions of Vitamin B12: Vitamin B12 contributes to normal energy yielding metabolism Vitamin B12 contributes to normal functioning of the nervous system Vitamin B12 contributes to normal homocysteine metabolism Vitamin B12 contributes to normal psychological function Vitamin B12 contributes to normal red blood cell formation Vitamin B12 contributes to the normal function of the immune system Vitamin B12 contributes to the reduction of tiredness and fatigue Vitamin B12 has a role in the process of cell division