Vitamin B12 Deficiency Vitamin B12 has many important functions
in the body. It works with the B vitamin folate to make our
body's genetic material. It helps keep levels of the amino acid
homocysteine in check, which may help decrease heart disease
risk, and it is essential to the production of red blood cells,
which carry oxygen through the blood to the body's tissues. But
many people are deficient in this important vitamin. Causes of
Vitamin B12 Deficiency Vitamin B12 deficiency can have a number
of possible causes. Typically it occurs in people whose
digestive systems do not adequately absorb the vitamin from the
foods they eat. This can be caused by: - Pernicious anemia, a
condition in which there is a lack of a protein called intrinsic
factor. The protein, which is made in the stomach, is necessary
for vitamin B12 absorption. - Atrophic gastritis, a thinning of
the stomach lining that affects up to 30% of people aged 50 and
older. - Surgery in which part of the stomach and/or small
intestine is removed.