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Total in Dietary Folate Equivalents


300 plus diet

Serum folate low in 40%


1,000 plus diet

Increase 40–60% abnormal erythrocyte folate normal level compared with 10–20% in supplemented group

≤ 100

200 plus diet

600 plus diet

900 plus diet

Prevented deficiency in 72%, 84%, and 94%, respectively, comparable with nonpregnancy control

100 plus diet

200 plus diet

400 plus diet

1,000 plus diet

Decrease in serum folate in 15%; normal level serum folate

660 plus diet

Prevented deficiency in supplemented groups


200 plus diet

Maintained normal levels erythrocyte folate


510 plus diet

850 plus diet

1,700 plus diet

Folate depletion

No apparent folate depletion

Three of the four studies provided data that 100 to 150 µg/day of supplemental folate plus a low-folate diet was inadequate to maintain normal serum and hematological indices, which were the only outcomes measured in all of the subjects. The accuracy of the dietary estimates could not be ascertained, but they were lower than the one analyzed intake estimate (676 µg/day) reported by Chanarin and coworkers (1968).

Other Evidence Considered. McPartlin and colleagues (1993) quantitated the urinary excretion of the major folate catabolites in six pregnant women and six nonpregnant control subjects. These in-

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