Discuss the groups of people most at risk for vitamin B12 deficiency and why they are at risk.

Question

What will be an ideal response?

Answer 1

Most vitamin B12 deficiencies reflect inadequate absorption, not poor intake. Inadequate absorption typically occurs for one of two reasons: a lack of hydrochloric acid or a lack of intrinsic factor. Without hydrochloric acid, the vitamin is not released from the dietary proteins and so is not available for binding with the intrinsic factor. Without the intrinsic factor, the vitamin cannot be absorbed.
So, those most at risk include those who are unable to absorb vitamin B12 because they lack hydrochloric acid or intrinsic factor. They include

• adults who use heartburn medicines because the medicine suppresses gastric acid products.

• people who have atrophic gastritis, a condition that damages the cells of the stomach. Older people often develop this condition. It also may develop in response to iron deficiency or infection with Helicobacter pylori, the bacterium implicated in ulcer formation. Without healthy stomach cells, production of hydrochloric acid and intrinsic factor diminishes. Even with an adequate intake from foods, vitamin B12 status suffers. The vitamin B12 deficiency caused by atrophic gastritis and a lack of intrinsic factor is known as pernicious anemia.

• people who have inherited a defective gene for the intrinsic factor. (In such cases, or when the stomach has been injured and cannot produce enough of the intrinsic factor, vitamin B12 must be given by injection to bypass the need for intestinal absorption. It also can be delivered by nasal spray.)

Because vitamin B12 is found primarily in foods derived from animals, vegetarians, and especially vegans, are especially likely to develop a vitamin B12 deficiency (although it may take several years for people who stop eating animal-derived foods to develop deficiency symptoms because the body recycles much of its supply).