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. Vitamin B12 deficiency can cause damage to your nerves and can affect memory and thinking.
What causes vitamin B12 deficiency anemia?
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.
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
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. Other causes include drinking alcohol and taking some prescription and nonprescription medicines.
What is the recommended daily amount of vitamin B12?
The amount of vitamin B12 you need depends on your age.
Daily recommended B12:1
| Age (years)|| Daily amount of B12 (micrograms)|
|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.
Estimates of B12 in certain foods2
| Food|| Serving size|| B12 amount (microgram)|
|Beef liver||3 ounces||71 mcg|
|Clams||3 ounces||84 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|