In comparison to other water-soluble vitamins, vitamin B12 is not excreted in urine, but is stored in the liver, kidney and other body tissues. Hence, it might be five to six years before a person actually develops a deficiency syndrome for vitamin B12. The general notion is that body stores do no exhaust before several years.

The common symptoms of vitamin B12 deficiencies are excessive tiredness, breathlessness, listlessness, pallor and poor resistance to infection. Deficiency also can lead to neurological changes such as numbness and tingling in the hands and feet. Other symptoms may include a reduced sensitivity to pain or pressure, blurred vision, abnormal gait, sore tongue, menstrual disorders and poor concentration levels.

Rather than a dietary deficiency, a deficiency of vitamin B12 is generally associated with a malabsorption of it. In such a case, the stomach cannot produce enough of a substance called intrinsic factor (IF), which is a prerequisite for vitamin B12 absorption. Such a condition, termed pernicious anemia, is an autoimmune dysfunction, wherein the body