Vitamin B12 Deficiency Anemia
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.
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 lightheaded.
- 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.
- 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:
If your vitamin B12 deficiency anemia 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. Symptoms develop slowly over years, as the amount of vitamin B12 absorbed by the body decreases and the vitamin B12 stored in your body is used up.
As the anemia becomes worse, you may have:
- A pale appearance.
- A sore, red tongue or bleeding gums.
- Loss of taste and appetite with weight loss.
- Diarrhea or constipation.
- A rapid heartbeat or chest pain.
- Shortness of breath upon exertion.
Low levels of vitamin B12 cause damage to the brain and nerve cells. The symptoms this causes may be the first ones you notice. They can include:
- Numbness or tingling in the fingers and toes.
- Poor balance and coordination.
- Difficulty thinking and concentrating.
- Impaired judgment and poor control of impulses.
- A decreased ability to sense vibration.
- Ringing in the ears (tinnitus).
- Dementia, a decline in mental abilities that is severe enough to interfere with daily life.
Exams and Tests
If vitamin B12 deficiency anemia is suspected, your doctor will do a physical exam and ask questions about your medical history and symptoms. You will also have blood tests, such as:
- Complete blood count (CBC). This test gives important information about the kinds and numbers of cells in the blood. Having a low red blood cell count is a sign of anemia. Vitamin B12 deficiency anemia causes the red blood cells to be larger than normal, so it is called a macrocytic (meaning big cells) or megaloblastic (big, immature-looking cells) anemia. Problems other than vitamin B12 deficiency anemia also can cause macrocytic anemia.
- Vitamin B12 test to measure the level of this vitamin in the blood.
- Folic acid test. Folic acid is another type of B vitamin. Some people who have vitamin B12 deficiency anemia also have folic acid deficiency anemia, and both of these deficiencies cause similar symptoms.
- Tests to detect the presence of certain antibodies that may help diagnose pernicious anemia.
- Homocysteine test and methylmalonic acid (MMA) test. The amount of these substances in the blood rises as the level of vitamin B12 decreases. Your doctor may use these tests to check to see why vitamin B12 levels may be borderline low.
Having pernicious anemia may increase a person's risk of developing stomach cancer. If you have pernicious anemia, you may need to ask your doctor whether you should be screened for stomach cancer on a regular basis.
Vitamin B12 deficiency anemia is treated with supplements of vitamin B12. When the level of vitamin B12 has returned to normal, your body will produce more red blood cells and the symptoms will go away. However, most people need to take supplements for the rest of their lives to prevent the condition from returning. This is because the usual cause of vitamin B12 deficiency is poor absorption of the vitamin through the intestine. If you stop taking the supplements, your B12 level will fall again.
At first, you will get shots of vitamin B12 (100 to 1,000 micrograms [mcg]). You may get a shot every day for 1 week, then once a week for a month, and then once every month. Or your doctor may have you take pills (1,000 to 2,000 mcg a day) that contain a higher dose of vitamin B12 than a regular vitamin pill. You don't need to worry about getting too much vitamin B12, because your body will pass extra vitamin B12 out in the urine. Most people feel better within days of beginning treatment.
If another condition is interfering with your body's ability to absorb vitamin B12, your doctor usually will treat it at the same time as the vitamin deficiency. For example, a bacterial infection in the bowels can be treated with antibiotics.
Often vitamin B12 deficiency anemia is not diagnosed until it is moderate to severe. This is because the anemia develops slowly and the symptoms can be subtle. If your anemia is severe, you may need a blood transfusion. In older adults who have transfusions, special care must be taken to avoid heart failure or pulmonary edema. Treatment may not completely correct the symptoms caused by damage to the brain and nerve cells.
Your doctor will recheck your vitamin B12 levels in a few months to make sure the treatment is working. You will need to take your shots or pills just as your doctor advises to keep the deficiency from returning. Most people need to take pills or shots for the rest of their lives.
Another form of treatment is a vitamin B12 nasal spray (Nascobal). But the nasal spray costs more than shots or pills and is not commonly used.
You can take steps at home to improve your health by eating a varied diet that includes meat, milk, cheese, and eggs, which are good sources of vitamin B12. Also eat plenty of foods that contain folic acid, another type of B vitamin. These include leafy green vegetables, citrus fruits, and fortified cereals.
What to Think About
The standard form of treatment for vitamin B12 deficiency anemia has been shots given into the muscle (intramuscular). But for many people, vitamin B12 pills can be as effective as shots. These vitamin B12 pills contain a higher dose of vitamin B12 than a regular vitamin pill. You don't need to worry about getting too much vitamin B12, because your body will pass extra vitamin B12 out in the urine. Pills are also less expensive and more convenient. If you have been getting shots, you might want to ask your doctor if you could switch to pills. You may need follow-up testing to make sure your body is absorbing the vitamin.
If you have vitamin B12 deficiency anemia, you can take steps at home to improve your health:
- Eat a varied diet that provides enough vitamin B12 for your body's needs. If you do not eat any animal products (including meat, milk, cheese, and eggs), you can get your vitamin B12 by eating foods fortified with this vitamin or by taking vitamin pills that contain it.
- Eat foods that have folic acid (folate), another type of B vitamin. This is particularly important after you start treatment for vitamin B12 deficiency anemia. Foods that contain folic acid include leafy green vegetables, citrus fruits, and fortified cereals. For more information, see the topic Folic Acid Deficiency Anemia.
- If your blood is also low in iron, you may need to take iron supplements. For more information, see the topic Iron Deficiency Anemia.
If you have been taking shots, ask your doctor if you could switch to pills. For many people, vitamin B12 pills (1,000 to 2,000 micrograms [mcg] a day) can be as effective as shots. These vitamin B12 pills contain a higher dose of vitamin B12 than a regular vitamin pill. You don't need to worry about getting too much vitamin B12, because your body will pass extra vitamin B12 out in the urine. Pills are also less expensive and more convenient. You may need follow-up testing to make sure your body is absorbing the vitamin.
If you need to take shots, you can learn to give them to yourself. A doctor can teach you how to store the medicine and where to give the shots. If you are unable to do it yourself, a family member can learn to give the shots.
You will need to take your shots or pills just as your doctor advises to keep the deficiency from returning. Most people need to take pills or shots for the rest of their lives.
Other Places To Get Help
|National Heart, Lung, and Blood Institute (NHLBI)|
|P.O. Box 30105|
|Bethesda, MD 20824-0105|
The U.S. National Heart, Lung, and Blood Institute (NHLBI) information center offers information and publications about preventing and treating:
|Office of Dietary Supplements, National Institutes of Health|
|6100 Executive Blvd., Room 3B01, MSC 7517|
|Bethesda, MD 20892-7517|
The Office of Dietary Supplements (ODS) supports research and disseminates research results in the area of dietary supplements. The ODS also provides advice to other federal agencies regarding research results related to dietary supplements.
Other Works Consulted
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- Babior BM, Bunn HF (2005). Megaloblastic anemias. In DL Kasper et al., eds., Harrison's Principles of Internal Medicine, 16th ed., pp. 601–607. New York: McGraw-Hill.
- Carmel R (2006). Cobalamin (Vitamin B12). In ME Shils et al., eds., Modern Nutrition in Health and Disease, 10th ed., pp. 482–497. Philadelphia: Lippincott Williams and Wilkins.
- Carmel R, et al. (2005). Vitamin B12 deficiency anemia: Essentials of diagnosis. In LM Tierney et al., eds., Current Medical Diagnosis and Treatment, 44th ed., pp. 468–470. New York: Lange Medical/McGraw-Hill.
- Gallagher ML (2008). The nutrients and their metabolism. In LK Mahan, S Escott-Stump, eds., Krause's Food and Nutrition Therapy, 12th ed., pp. 92–94. Philadelphia: Saunders Elsevier.
- Heimburger DC, et al. (2006). Clinical manifestations of nutrient deficiencies and toxicities: A resume. In ME Shils et al., eds., Modern Nutrition in Health and Disease, 10th ed., pp. 595–611. Philadelphia: Lippincott Williams and Wilkins.
- Hillman RS, et al. (2005). Macrocytic anemias. In Hematology in Clinical Practice, 4th ed., pp. 95–109. New York: McGraw-Hill.
- Oh RD, Brown DL (2003). Vitamin B12 deficiency. American Family Physician, 67(5): 979–986.
- Tisman G (2005). Pernicious anemia and other megaloblastic anemias. In RE Rakel, ET Bope, eds., Conn's Current Therapy 2005, pp. 443–448. Philadelphia: Elsevier Saunders.
|Author||Caroline Rea, RN, BS, MS|
|Editor||Susan Van Houten, RN, BSN, MBA|
|Associate Editor||Denele Ivins|
|Primary Medical Reviewer||Anne C. Poinier, MD - Internal Medicine|
|Specialist Medical Reviewer||Brian Leber, MDCM, FRCPC - Hematology|
|Last Updated||December 19, 2008|