is mainly obtained from animal products. It serves as a coenzyme in the synthesis of DNA and is also essential for various metabolisms in the body.
Deficiency of Vitamin B12 results in a megaloblastic anemia
(red blood cells are abnormally large). When the cause is a lack of vitamin B12 due to malabsorption in the intestines, it is called pernicious anemia
is absorbed in the distal ileum after combining with intrinsic factor (IF) secreted by stomach; The vitamin B12/ IF complex attaches to a specific receptor in the terminal ileum and the vitamin B12 enters into the circulation.
Once absorbed vitamin B12 is transported to various cells of the body by the transcobalamines. Excess vitamin B12 is transported to the liver for storage and excreted in the urine.
Causes of Pernicious Anemia
Lack of intrinsic factor (necessary for absorption of vitB 12) due to an autoimmune condition, in which the body's immune system attacks parietal cells and intrinsic factor is the cause of pernicious anemia.
For intrinsic factor deficiency, Vit B12 therapeutic preparations should be given parenterally. Patients with pernicious anemia will need life-long therapy.