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97 to 98 percent of the individuals in the group (therefore, for B12 the RDA is 120 percent of the EAR).

RDA for Men

19–30 years

2.4 µg/day of vitamin B12

 

31–50 years

2.4 µg/day of vitamin B12

RDA for Women

19–30 years

2.4 µg/day of vitamin B12

 

31–50 years

2.4 µg/day of vitamin B12

Adults Ages 51 Years and Older

Evidence Considered in Estimating the Average Requirement

Because 10 to 30 percent of people older than 50 years are estimated to have atrophic gastritis with low stomach acid secretion (Andrews et al., 1967; Hurwitz et al, 1997; Johnsen et al., 1991; Krasinski et al., 1986), they may have decreased bioavailability of B12 from food. Therefore, because of the high prevalence of this condition, 50 percent bioavailability of dietary B12 (see Box 9-2) cannot be assumed for this age group, and the EAR would be higher than 2.0 µg. Similarly, 2.4 µg of B12, which is the RDA for younger adults, might not meet the needs of 97 percent of this large age group. There is not sufficient information on which to base a bioavailability correction factor for persons with atrophic gastritis who obtain their B12 from animal foods. However, because the bioavailability of crystalline B12 is not altered in people with atrophic gastritis, the same EAR and RDA would apply if the dietary sources of B12 were foods fortified with B12, supplements, or a combination of both.

B12EAR and RDA Summary, Ages 51 Years and Older

The EAR and RDA for B12 for adults ages 51 years and older are the same as for younger adults but with the recommendation that B12-fortified foods (such as fortified ready-to-eat cereals) or B12-containing supplements be used to meet much of the requirement.

EAR for Men

51–70 years

2 µg/day of vitamin B12*

 

> 70 years

2 µg/day of vitamin B12*

EAR for Women

51–70 years

2 µg/day of vitamin B12*

 

> 70 years

2 µg/day of vitamin B12*



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