Folate catabolism in pregnant and nonpregnant women with controlled folate intakes.

Measurement of the urinary folate catabolites, para-aminobenzoylglutamate (pABG) and the more predominant acetylated form, acetamidobenzoylglutamate (apABG), has been used to assess folate requirements in both pregnant and nonpregnant women. Folate catabolite excretion has been reported to be significantly higher in pregnant women (second trimester) compared with nonpregnant controls. The primary goals of this study were to determine if pregnant women in a controlled metabolic study excreted higher quantities of urinary folate catabolites than nonpregnant controls and if catabolite excretion was influenced by folate intake. We evaluated the effect of gestation and folate intake on the urinary excretion of apABG and pABG in pregnant women (n = 12; wk 14-26 gestation) and nonpregnant controls (n = 12) assigned to consume folate levels approximating the current (400 microg/d) and previous (800 microg/d) RDA. Subjects were fed a controlled diet containing 120 microg folate/d and either 330 or 730 microg synthetic folic acid/d. In contrast to previously reported data, no differences in mean folate catabolite excretion were detected between pregnant and nonpregnant subjects. Catabolite excretion (pABG + apABG) decreased significantly relative to initial values in pregnant women consuming 450 microg folate/d (-40 +/- 20%; mean +/- SD) and final mean excretion was significantly lower in the pregnant women consuming 450 microg folate/d (86 +/- 32 nmol/d) compared with 850 microg folate/d (148 +/- 20 nmol/d). Data from this study indicate that second trimester pregnant women do not excrete more folate catabolites than nonpregnant controls and that consumption of 450 vs. 850 microg folate/d results in a significant reduction in the quantity of folate catabolites excreted.