Vitamin B12 is water- soluble vitamin. It plays an important role in the normal function of the nervous and immune systems, energy production, the formation of red blood cells, the metabolism of folate, bone health, DNA synthesis, and in both fatty acid and amino acid metabolism. It also contributes to psychological function and a reduction in tiredness and fatigue. Together with folate and vitamin B6, vitamin B12 is required for maintenance of normal blood homocysteine levels.