What Is Pernicious Anemia?

Pernicious anemia is caused by a lack of vitamin B12. The main reason for vitamin B12 deficiency is a loss of cells in the lining of the stomach that help the body absorb B12 in the small intestine.

In some people, this is the result of an abnormal autoimmune function that attacks these cells in the lining of the stomach. Over time, the stomach stops producing the cells, causing a B12 deficiency.

In others, pernicious anemia is the result of the stomach lining being removed during surgery or the result of a rare inherited disorder.
The most common reasons for pernicious anemia are a diet low in vitamin B12, intestinal problems, certain medicines, alcoholism, and aging.

Strict vegetarians and vegans can develop pernicious anemia— especially if they do not eat meat, poultry, fish, eggs, or dairy products, which are the best sources of vitamin B12.

Infants breastfed by strict vegetarian mothers can develop anemia quickly due to insufficient B12 intake. They can be given vitamin B12 supplements to prevent this type of anemia.