The relationship between increased folate catabolism and the increased requirement for folate in pregnancy

Objectives To estimate the rate of folate catabolism in pregnant and nonpre gnant women and to derive the recommended dietary allowance for folate. Design Prospective, observational study. Setting Rotunda Hospital, Dublin. Women Twenty-four healthy gravid women were studied once during each trimes ter and postpartum. Twenty-five nonpregnant controls were assessed before a nd after folic acid supplementation. Interventions Women provided 24-hour urine collections while adhering to a strict dietary regimen containing no exogenous folate catabolites. Main outcome measures Urinary levels of p-acetamidobenzoylglutamate and p-a minobenzoylglutamate were measured by high pressure liquid chromatography. Results The 24-hour excretion of folate catabolites, expressed as mean [95% CI] folate equivalents in mu g) progressively increased during pregnancy. A peak was reached in the third trimester (349.1 mu g [308.1 to 390.1]) whe re the rare was more than twice the rate in the nonpregnant control group ( 136.4 mu g [112.4 to 160.4]) (P < 0.001). Based on our results the recommen ded dietary allowance for folate in nonpregnant women should be 250 mu g an d this should rise during pregnancy to 430 mu g in the second trimester and 540 mu g in the third trimester. Conclusions The race of folate catabolism progressively increases during pr egnancy reaching a peak in the third trimester at the time of maximal fetal growth. The increased demand for folate during pregnancy appears to be due to the accelerated breakdown of the vitamin because of its participation i n cellular biosynthesis. These results provide a quantitative basis for the current debate on the appropriate recommended dietary allowance for folate in both pregnant and nonpregnant women.