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 mu g/d of total folate for 70 d which was provided by low folate conventiona l foods (30 mu g) plus supplemental folic acid. Group means for initia l serum and erythrocyte folate and plasma homocysteine concentrations were not significantly different, Serum and erythrocyte folate decreas ed relative to the initial value in the 200 mu g/d group (43.4 +/- 12. 1%, 13.6 +/- 16.6%, respectively; mean +/- SD), in contrast to an incr ease in the 400 mu g/d group (16.8 +/- 52.0%, 10.2 +/- 18.5%, respecti vely). The final serum folate in the 200 and 300 mu g/d groups (6.4 +/ - 0.8 nmol/L, 7.3 +/- 1.1 nmol/L, respectively) was significantly lowe r than that of the 400 mu g/d group (14.3 +/- 2.0 nmol/L), with eviden ce in the 200 mu g/d and 300 mu g/d groups of low (<6.8 nmol/L) serum folate concentrations. Differences in final erythrocyte folate did not reach statistical significance, although low values (<362 nmol/L) wer e frequent in subjects with 200 mu g/d intake, In the 200 mu g/d group , plasma homocysteine was negatively correlated with serum and erythro cyte folate, and final mean plasma homocysteine (12.6 +/- 1.7 mu mol/L ) was significantly higher than that of the 300 or 400 mu g/d groups. Elevated plasma homocysteine levels (>16 mu mol/L) were observed in th e 200 mu g/d group only. Data from this study indicate that 200 mu g/d of folate was not sufficient to maintain folate status of these women and suggest that the current RDA of 180 mu g/d may not be adequate to meet the dietary folate intake needs of nonpregnant women.