What causes a person to lose B-12 from their body?

Question

My doctor did a blood test on me and said I had low B-12 and told me to get B-12 supplements from the store. What causes a person to lose this?

Answer 1

The most common cause of a loss of B-12 is not getting enough of it in your diet. This is particularly true in vegans since B-12 is found in meats, fish, poultry, eggs and dairy products.

Another cause is the loss of parietal cells in the lining of the stomach. These cells help the body to absorb B-12. The body's immune system may attack these parietal cells. The reason is unknown. This can lead to pernicious anemia.

Other causes are:
crohn's disease
celiac disease
some medications