Vit B 12 is absorbed in
The  cobalamin-lF complex travels through the gut. The complex binds to specific receptors on the surface of the mucosal cells of the ileum. The binding of the complex and entry of B12 into the mucosal cells is mediated by Ca2+ ions. In the  mucosal  cells,  B12  is  converted  to methyf cobalamin. lt is then transported in the circulation in  a  bound form to  proteins namely  transcobalamins.
Stomach
Deudenum
Ileum
Colon