DefinitionVitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the body through the urine.Typically, water-soluble vitamins can not be stored by the body. Vitamin B12 is special, because the body can store it for years in the liver.Alternative NamesCobalamin; Deficiency - B12FunctionVitamin B12, like the other B vitamins, is important for metabolism. It helps in the formation of red blood cells and in the maintenance of the central nervous system.Food SourcesVitamin B12 is found in eggs, meat, poultry, shellfish, milk, and milk products.Side EffectsVitamin B12 deficiencies occur when the body is unable to properly use the vitamin. Pernicious anemia can make the body unable to absorb vitamin B12 from the