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EAR for Lactation

14–18 years

2.4 µg/day of vitamin B12

19–30 years

2.4 µg/day of vitamin B12

31–50 years

2.4 µg/day of vitamin B12

The RDA for B12 is set by assuming a coefficient of variation (CV) of 10 percent (see Chapter 1) because information is not available on the standard deviation of the requirement for B12; the RDA is defined as equal to the EAR plus twice the CV to cover the needs of 97 to 98 percent of the individuals in the group (therefore, for B12 the RDA is 120 percent of the EAR).

RDA for Lactation

14–18 years

2.8 µg/day of vitamin B12

19–30 years

2.8 µg/day of vitamin B12

31–50 years

2.8 µg/day of vitamin B12

Special Considerations

Persons with any malabsorption syndrome will likely require increased amounts of B12. Patients with pernicious anemia or Crohn’s disease involving the terminal ileum and patients who have had a gastrectomy, gastric bypass surgery, or ileal resection will require B12 under a physician’s direction. Persons who are positive for human immunodeficiency virus with chronic diarrhea may also require either increased oral or parenteral B12.

Patients with atrophic gastritis, pancreatic insufficiency, or prolonged omeprazole treatment (Bellou et al., 1996; Gueant et al., 1990; Suter et al., 1991; Termanini et al., 1998) will have decreased bioavailability of food-bound B12 and will require normal amounts of crystalline B12 (either in foods fortified with B12 or as a supplement).

INTAKE OF VITAMIN B12

Food Sources

Ordinarily, humans obtain vitamin B12 from animal foods. Unlike other B vitamins, B12 is not a normal constituent of plant foods except for certain algae (Ford and Hutner, 1955). B12 is not supplied by commonly eaten plant foods unless they have been exposed to bacterial action that has produced the vitamin; contaminated with soil, insects, or other substances that contain B12; or fortified with B12 (e.g., fortified ready-to-eat breakfast cereals and meal replacement formulas).

Data obtained from the 1995 Continuing Survey of Food Intakes



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