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higher for men than for women. The increase due to age and gender appears to be approximately 0.2 to 0.3 mg of food B6/day.

EAR for Men

51–70 years

1.4 mg/day of vitamin B6

 

> 70 years

1.4 mg/day of vitamin B6

EAR for Women

51–70 years

1.3 mg/day of vitamin B6

 

> 70 years

1.3 mg/day of vitamin B6

The RDA for B6 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 B6; 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 B6 the RDA is 120 percent of the EAR).

RDA for Men

51–70 years

1.7 mg/day of vitamin B6

 

> 70 years

1.7 mg/day of vitamin B6

RDA for Women

51–70 years

1.5 mg/day of vitamin B6

 

> 70 years

1.5 mg/day of vitamin B6

Special Considerations

Note that the EARs (and RDAs) for adults were derived by using biochemical indicator cutoff values that have not been directly linked to clinical or physiological insufficiency. As described above, clinical symptoms of B6 deficiency have been observed only in controlled studies during depletion with very low levels of B6 and have never been seen at intakes of 0.5 mg/day or greater. This suggests that 1 mg/day is sufficient for most adults, but requirements may possibly be higher in individuals on very-high-protein diets.

Pregnancy

Evidence Considered in Estimating the Average Requirement

Concentrations of indicators of B6 status in plasma and blood decrease throughout pregnancy, especially in the third trimester (Cleary et al., 1975; Hamfelt and Tuvemo, 1972; Shane and Contractor, 1980). Many studies have demonstrated a drop in plasma PLP to about 10 nmol/L; this is substantially more than can be accounted for by increased blood volume. Fetal blood PLP concen-



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