Persons
At Risk for Vitamin B12 Deficiency
Vitamin
B12 naturally occurs in the highest concentrations in meat and dairy products. Persons who have a decreased intake of vitamin B12,
are unable to absorb dietary vitamin B12, or have genetic conditions that
interfere with B12 metabolism are at risk for vitamin B12
deficiency.[60] Persons who fall into the following categories
should be counseled or referred on how to obtain sufficient amounts of vitamin B12.
Decreased
intake[61]
§ Vegetarian/vegan/macrobiotic
diet
§ Breast-fed
infants of mothers with unrecognized vitamin B12 deficiency related to
pernicious anemia
Abnormal
absorption[61]
1. Absence/dysfunction
of intrinsic factor, due to gastric resection,
autoimmune pernicious anemia, or absent/abnormal formation of intrinsic factor (genetic)
2. Decreased gastric
acid, due to long-term therapy with medications that
decrease gastric acid secretion
3. Pancreatic
insufficiency
4. Competition for B12
in intestine, due to parasitic infection or
bacterial overgrowth
5.
Disruption of
absorption in ileum (small intestine)
6.
Older persons[59]
Genetic Factors[61]