The body needs this B vitamin to make blood cells and to maintain a healthy nervous system.
A Vitamin B12 test measures the amount of Vitamin B12 in the blood and is usually measured at the same time as a folic acid test because a lack of either one can lead to a form of anemia called megaloblastic anemia. Lack of Vitamin B12 can also affect the nervous system.
Vitamin B12 is found in animal products such as meat, shellfish, milk, cheese, and eggs. Strict vegetarians (vegans) who do not eat animal products and babies of mothers who are strict vegetarians are at increased risk for developing anemia and should take a supplement containing Vitamin B12.