Question

What is the role of vitamin B12? How is vitamin B12 absorbed?

Answer 1

Th vitamin B12 is also called cobalamin. It is a water soluble vitamin playing a key role in the red blood cell production from the bone marrow, proper function of the nervous system and DNA synthesis in the body. Vitamin B12 serves as a cofactor during the synthesis of DNA and in the production of amino acids and fatty acids in the body. It plays a key role in the synthesis of myelin and thus important for the proper functioning of the nervous system. It also helps in the maturation process during the red blood cell development.

The vitamin B12 is absorbed via specific intestinal mechanism involving an intrinsic factor. The ingested vitamin B12 if it is in a free form, it will bind with a carrier protein called R-binders. These R-binders are secreted by salivary glands and the mucosal cells of the stomach. If the vitamin is ingested in a protein bound form, the gastric proteolytic enzymes cleaves the protein and the vitamin B12 binds with the R-binder present in the stomach. When the Vitamin B12 - R binder complex reaches the second segment of the duodenum, the proteases secreted by pancreas degrade the R-binder from the complex. Further, the free vitamin B12 binds with intrinsic factor and it passes to ileum. The intrinsic factor protects the vitamin from the degradation by the intestinal microbes. Ileum is a part of small intestine where it recognizes the Vitamin B12 - intrinsic factor complex and the vitamin B12 is absorbed.