<prompt> Vit B 12 is absorbed inStomachDeudenumIleumColon  <response>: 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. 