Vitamin B12 Deficiency Anemia

Topic Overview

What is vitamin B12 deficiency anemia?

Having vitamin B12 deficiency means that your body does not have enough of this vitamin. You need B12 to make red blood cells, which carry oxygen through your body. Not having enough B12 can lead to anemia, which means your body does not have enough red blood cells to do the job. This can make you feel weak and tired.

What causes vitamin B12 deficiency anemia?

Most people get more than enough B12 from eating meat, eggs, milk, and cheese. Normally, the vitamin is absorbed by your digestive system—your stomach and intestines. Vitamin B12 deficiency anemia usually happens when the digestive system is not able to absorb the vitamin. This can happen if:

• You have pernicious anemia. In this anemia, your body destroys the cells in your stomach that help you absorb vitamin B12.
• You have had surgery to remove part of the stomach or the last part of your small intestine, called the ileum. This includes some types of surgery used to help very overweight people lose weight.
• You have problems with the way your body digests food, such as sprue (also called celiac disease), Crohn's disease, bacteria growth in the small intestine, or a parasite.
• You take medicine for heartburn and ulcers for a long time.

This anemia can also happen if you don't eat enough foods with B12, but this is rare. People who eat a vegan diet and older adults who don't eat a variety of foods may need to take a daily vitamin pill to get enough B12.

What are the symptoms?

If your vitamin B12 deficiency is mild, you may not have symptoms or you may not notice them. Some people may think they are just the result of growing older. As the anemia gets worse, you may:

• Feel weak, tired, and light-headed.
• Have pale skin.
• Have a sore, red tongue or bleeding gums.
• Feel sick to your stomach and lose weight.
• Have diarrhea or constipation.

If the level of vitamin B12 stays low for a long time, it can damage your nerve cells. If this happens, you may have:

• Numbness or tingling in your fingers and toes.
• A poor sense of balance.
• Depression.
• Dementia, a loss of mental abilities.

How is vitamin B12 deficiency anemia diagnosed?

Your doctor will examine you and ask questions about your past health and how you are feeling now. You will also have blood tests to check the number of red blood cells and to see if your body has enough vitamin B12.

The level of folic acid, another B vitamin, will be checked too. Some people whose vitamin B12 levels are too low also have low levels of folic acid. The two problems can cause similar symptoms.

How is it treated?

Treatment is usually regular shots of vitamin B12 in the arm or another muscle. You may get a shot every day for 1 week, then once a week for a month, and then once every month. You can learn to give yourself shots or have a family member learn how to do it.

For many people, pills work just as well as shots. They also cost less and are easier to take. If you have been getting shots, ask your doctor if you can switch to pills.

Most people who get this anemia need to take pills or shots for the rest of their lives.

Can vitamin B12 deficiency anemia be prevented?

Most people can prevent this anemia by including animal products like milk, cheese, and eggs in their diets. People who follow a vegan diet can prevent it by taking a daily vitamin pill or by eating foods that have been fortified with B12.

Babies born to women who eat a vegan diet should be checked by a doctor to see whether they need extra vitamin B12.

If you have had surgery to remove part of your stomach or small intestine, your doctor can give you vitamin B12 shots. These will keep you from developing this type of anemia.

If you have a condition such as sprue or Crohn's disease that might keep your small intestine from absorbing vitamin B12, ask your doctor if you need pills or shots.

Frequently Asked Questions

Learning about vitamin B12 deficiency anemia:	What is vitamin B12 deficiency anemia? What causes it? What increases my risk for this problem? What are the symptoms? Can it be prevented?
Being diagnosed:	How is vitamin B12 deficiency anemia diagnosed?
Getting treatment:	How is vitamin B12 deficiency anemia treated? Are there steps I can take at home to treat this problem?

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Author:	Douglas Dana Ralph Poore	Last Updated: April 30, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine Kathleen Romito, MD - Family Medicine Brian Leber, MDCM, FRCPC - Hematology
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