Folate and fetal growth

Abstract

Folate is a water-soluble B vitamin that is essential for various one-carbon transfer reactions including formate oxidation, amino acid metabolism, and biosynthesis of thymidylate and purines. The term "folate" represents all folate derivatives, including its synthesized form, pteroylglutamic acid (folic acid, FA). In humans, folate is known to be absorbed from the upper-small intestine. The bioavailability of FA is estimated to be 1.7 times higher than that of natural food folate. In recent years, folate has received enthusiastic attention because of its preventive effects on fetal neural tube defects if given periconceptionally. In addition, folate became one of the hottest nutrients of research interest in the last two decades, since elevated serum or plasma homocysteine has been implicated as a risk factor for occlusive vascular disease, and its metabolism is closely regulated by folate. Although we need to understand intricate metabolic changes of folate associated with human pregnancy, we do know that folate requirement increases during pregnancy to support fetal growth. To meet this increased demand, folate is actively transferred to the fetus across the placenta. The findings in many human studies are inconsistent in terms of the association of birthweight (considered to be the best assessment of fetal growth) to maternal dietary folate intake, biomarkers of folate status, and the effect of FA supplementation. We suggest that systematic and well-designed studies be performed to better understand folate metabolism during pregnancy and the critical period for adequate folate status to achieve optimal fetal growth.