Final answer:
Vitamin B12 requires the intrinsic factor, a glycoprotein secreted in the stomach, for its absorption in the small intestine due to its large molecular size. Without this factor, vitamin B12 cannot be effectively absorbed, leading to potential deficiencies and neurological issues.
Step-by-step explanation:
Vitamin B12 and Intrinsic FactorThe vitamin that needs an intrinsic factor for absorption is vitamin B12. This is necessary because vitamin B12 is a very large molecule that cannot be absorbed by simple diffusion like most vitamins. Instead, the intrinsic factor, a glycoprotein secreted by the gastric glands in the stomach, binds to vitamin B12, forming a complex that can then bind to mucosal receptors in the terminal ileum of the small intestine. The intrinsic factor-vitamin B12 complex is then absorbed by the body through a process called endocytosis. Without an intrinsic factor, vitamin B12 cannot be absorbed and this can lead to deficiencies, affecting the production of mature red blood cells and normal neurological functioning.
In the absence of a functioning stomach or if the intrinsic factor is not being produced, vitamin B12 injections are required to ensure survival and prevent disorders like pernicious anemia.Vitamin B12 is the vitamin that requires an intrinsic factor for absorption. The intrinsic factor is secreted in the stomach and binds to vitamin B12, preventing its digestion. This complex then binds to mucosal receptors in the terminal ileum of the small intestine, where it is taken up by endocytosis. This process is necessary for the proper absorption of vitamin B12, which is essential for the production of mature red blood cells and normal neurological functioning.