Controlled Dietary Folate Affects Folate Status in Nonpregnant Women

In a study designed to estimate the requirement for dietary folate in nonpregnant women, 17 women (21-27 y) consumed 200, 300, or 400 μg/d of total folate for 70 d which was provided by low folate conventional foods (30 μg) plus supplemental folic acid. Group means for initial serum and erythrocyte folate and plasma homocysteine concentrations were not significantly different. Serum and erythrocyte folate decreased relative to the initial value in the 200 μg/d group (43.4 ± 12.1%, 13.6 ± 16.6%, respectively ; mean ± SD), in contrast to an increase in the 400 μg/d group (16.8 ± 52.0%, 10.2 ± 18.5%, respectively). The final serum folate in the 200 and 300 μg/d groups (6.4 ± 0.8 nmol/L, 7.3 ± 1.1 nmol/L, respectively) was significantly lower than that of the 400 μg/d group (14.3 ± 2.0 nmol/L), with evidence in the 200 μg/d and 300 μg/d groups of low ( 16 μmol/L) were observed in the 200 μg/d group only. Data from this study indicate that 200 μg/d of folate was not sufficient to maintain folate status of these women and suggest that the current RDA of 180 μg/d may not be adequate to meet the dietary folate intake needs of nonpregnant women.