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Consequently, an extra 0.5 mg/day of B6 can be reasonably justified to meet the need in the third trimester.

B6EAR and RDA Summary, Pregnancy

Although 0.5 mg/day of B6 may overestimate the additional need in early gestation, it was considered judicious to err on the side of ensuring sufficiency and add 0.5 mg/day to the EAR for nonpregnant women throughout pregnancy. Because of the approximation involved, no additional adjustment for adolescence is included.

EAR for Pregnancy

14–18 years

1.6 mg/day of vitamin B6

 

19–30 years

1.6 mg/day of vitamin B6

 

31–50 years

1.6 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 Pregnancy

14–18 years

1.9 mg/day of vitamin B6

 

19–30 years

1.9 mg/day of vitamin B6

 

31–50 years

1.9 mg/day of vitamin B6

Lactation

Evidence Considered in Estimating the Average Requirement

As described above, the B6 concentration in human milk varies depending on the mother’s B6 intake, and some women consuming less than 2.5 mg/day of B6 produce milk with a B6 content that is not much higher than that associated with consuming formula that resulted in convulsions in infants because of low levels of B6. There is some variation in reported human milk B6 content, which may be due to methodological differences. Between individuals there are variations in milk B6 content at similar B6 intakes. Existing data previously described suggest that the amount of B6 required to increase the milk B6 content by a small increment is much higher than that increment and that the additional requirement for lactation is considerably in excess of that suggested by the amount secreted via lactation (Borschel et al., 1986; West and Kirksey, 1976).



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