Harvard Health Letter

By the way, doctor: Can I take a pill instead of B12 injections?

Can I take a pill instead of B12 injections?

Q. I have pernicious anemia, and I get a monthly injection of vitamin B12. I have heard that there may be a pill that I could take instead. Is that true?

A. Pernicious anemia is a condition that occurs when the body doesn't make enough red blood cells because of lack of vitamin B12, which is absorbed in the ileum (part of the small intestine). To be absorbed, the vitamin needs to be attached to a protein, called intrinsic factor, that's secreted in the stomach. Pernicious anemia occurs when people develop an autoimmune condition that reduces the production of intrinsic factor — and, therefore, the absorption of vitamin B12. A number of other conditions can also impair a person's ability to absorb B12, which is found in meat, dairy products, and vitamin-fortified products like breakfast cereals.

The liver normally stores up large amounts of B12, so it may take several years for the anemia to develop after absorption of the vitamin has stopped. Anemia may cause weakness, fatigue, dizziness, and a rapid heartbeat. B12 deficiency can also result in neurological problems.

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