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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.
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 is the recommended daily amount of vitamin B12?
The amount of vitamin B12 you need depends on your age.
| Age (years) | Daily amount of B12 (micrograms) |
|---|---|
| 1-3 | 0.9 mcg |
| 4-8 | 1.2 mcg |
| 9-13 | 1.8 mcg |
| 14 and older | 2.4 mcg |
| Pregnant women | 2.6 mcg |
| Breast-feeding women | 2.8 mcg |
What foods contain B12?
Vitamin B12 is found in foods from animals, such as meat, seafood, milk products, poultry, and eggs. It is not in foods from plants unless it has been added to the food (fortified). Some foods, like cereals, are fortified with vitamin B12.
Supplements containing only B12, or B12 along with other B vitamins and/or folate, are readily available. Also, B12 is usually in multivitamins. Check the label to find out how much B12 is in a supplement.
| Food | Serving size | B12 amount (microgram) |
|---|---|---|
| Beef liver | 3 ounces | 71 mcg |
| Clams | 3 ounces | 10 mcg |
| Cereal fortified with 100% daily value for B12 | 1 serving | 6 mcg |
| Rainbow trout | 3 ounces | 3 mcg |
| Nonfat plain yogurt | 8 ounces | 1 mcg |
| Large egg | 1 egg | ½ mcg |
| Chicken breast | ½ breast | ½ mcg |
What are the symptoms?
WebMD Medical Reference from Healthwise
Last Updated:
May 04, 2011
This information is not intended to replace the advice of a doctor.
Healthwise disclaims any liability for the decisions you make based on this
information.
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Vitamin B12 Deficiency Anemia Topics
Vitamin B12 Deficiency Anemia
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