Vitamin B12

Am I getting enough vitamin B12?

Most people in the United States get enough B12 from their diet. However, some people have trouble absorbing B12 from their food. The body absorbs B12 in two steps. First, hydrochloric acid in the stomach separates vitamin B12 from the protein that it’s attached to. Second, the freed vitamin B12 then combines with a protein made by the stomach, called intrinsic factor, and the body absorbs them together. Vitamin B12 in dietary supplements isn’t attached to protein and doesn’t

require the first step. However, B12 in supplements does need to combine with intrinsic factor to be absorbed.

People with pernicious anemia, an autoimmune disease, can’t make intrinsic factor. As a result, they have trouble absorbing vitamin B12 from foods and dietary supplements.

Vitamin B12 deficiency affects between 3% and 43% of older adults. Your doctor can test your vitamin B12 level to see if you have a deficiency.

Certain groups of people may not get enough vitamin B12 or have trouble absorbing it:

• Many older adults don’t have enough hydrochloric acid in their stomach to absorb the vitamin B12 that’s naturally present in food. People over 50 should get most of their vitamin B12 from fortified foods or dietary supplements because, in most cases, their bodies can absorb vitamin B12 from these sources.

• People with an autoimmune disease called atrophic gastritis might not absorb enough vitamin B12 because they make too little hydrochloric acid and intrinsic factor in their stomach.

• People with pernicious anemia do not make the intrinsic factor needed to absorb vitamin B12. As a result, they have trouble absorbing vitamin B12 from foods and dietary supplements. Doctors usually treat pernicious anemia with vitamin B12 shots, although very high doses of vitamin B12 given by mouth might also be effective.

• People who have had some types of stomach or intestinal surgery (for example, to lose weight or to remove part or all of the stomach) might not make enough hydrochloric acid and intrinsic factor to absorb vitamin B12.

• People with disorders of the stomach and small intestine, such as celiac disease or Crohn’s disease, might not absorb enough vitamin B12.

• People who eat little or no animal foods, such as vegetarians and vegans, might not get enough vitamin B12 from their diets. Only animal foods have vitamin B12 naturally. When pregnant women and women who breastfeed their babies are strict vegetarians or vegans, their babies might also not get enough vitamin B12.