Wednesday, May 19, 2010

Does Vitamin B12 have to be injected, or are the pills good enough?

I am a nurse who was trained that vitamin B-12 (cyanocobalamin) had to be given parenterally or sublingually. However, I have seen bottles in stores of the tablet form of B-12. I wonder if they are even absorbed by the GI tract. Has there been new science showing it can now be absorbed in the GI tract? Thanks in advance, Dorothy.

Dear Dorothy,

Great question, and I'm happy to answer because vitamin B12 is hands down my favorite vitamin! It has such unique characteristics, including the way it is absorbed in the body.

First B12 must bind to intrinsic factor in the stomach, where the environment is acidic. If someone is missing intrinsic factor (if they had their stomach removed due to multiple polyps, severe bleeding ulcers, or cancer) they would not be able to absorb the vitamin orally. Likewise if the acidic environment were changed (and this happens when people age, as well as in people who take antacids regularly) the B vitamin would not be absorbed if taken orally.

Next this compound of intrinsic factor bound to B12 (which used to be called the "extrinsic factor") travels to the terminal ileum (the last part of the small intestine) which is where absorption takes place. If you have a patient who has ileal disease (like Crohn's disease) or had this part of their intestine removed, they would need shots of B12 because an oral source of B12 would not be absorbed into their system.

Vitamin B12 pills are helpful to those who have no problems in their digestive system affecting normal absorption of the vitamin. Since B12 is only found in animal products, it is recommended that vegans take a supplement. They can swallow a pill and absorb it just as most people can absorb the vitamin from foods.

If, however, someone is suffering from a B12 deficiency due to an alteration in the physiology of their stomach or small intestine, they do need to take the injectable form since an oral supplement will not be effectively absorbed.
I hope this clears it up for you!

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