Folic acid supplementation and the developmental origins of health and disease: a comparison between birth cohort studies in Brazil and New Zealand

Abstract

During the reproductive years and specifically during pregnancy, a women's health has a profound impact upon the health of her child, both in utero and throughout childhood. Since the 1970s, studies have shown relationships between decreased maternal levels of folate and an increased risk of neural tube defects in the fetus. As a result, many countries have implemented supplementation of women with folic acid in the periconceptional period and first trimester of pregnancy as a public health policy. In addition, some countries have adopted mandatory fortification of flour with folic acid in order to reduce the incidence of neural tube defects. Folic acid refers to the oxidized synthetic compound, whereas folate refers to the various tetrahydrofolate derivatives naturally found in food. Studies have reported the presence of unmetabolized folic acid in the blood following the consumption of excessive folic acid from supplements and fortified foods. Such free folic acid is associated with an increased risk of diseases during adult life, for example, cancers of breast, prostate and colon. Moreover, such excessive amount of folic acid also may not be as effective in preventing neural tube defects, implying a U-shaped relationship between folic acid status and neural tube defects risk; however, there is a lack of consensus in the literature about this issue. In Brazil, the recommendation of the Ministry of Health is to supplement all women with 5000 ¼g of folic acid per day in the periconceptional period and the first trimester of pregnancy. In addition, the dietary folic acid intake of women in Brazil has increased since the introduction in 2004 of mandatory folic acid fortification of wheat and corn flours. In contrast, the New Zealand Ministry of Health recommendation is for women to take 800 ¼g of folic acid in the 4 weeks prior and 12 weeks after pregnancy. New Zealand did not adopted mandatory fortification of flour with folic acid. This population diversity of Brazil and New Zealand and the differences in folate public health policy between Brazil and New Zealand provides a valuable opportunity to study the interactions of maternal folic acid intake, ethnicity, culture, and environment with child health. By taking advantage of such diversity, we may gain a much more thorough understanding of health-disease process, its causes, and its distribution that will benefit all. This project aims to compare the women's folic acid intake during pregnancy in two birth cohort studies: the ProcriAr study in Brazil and the Growing Up in New Zealand study in New Zealand. A literature review will be conducted to better understand the differences between countries regarding social and economical aspects, dietary habits, maternal and child health, folic acid recommendation and public health policies related to this field. Descriptive analysis of population characteristics will be presented in an attempt to characterize and compare the countries (measures of central tendency and dispersion, tests for comparison of mean and proportion). The prevalence of folic acid supplement use will also be described. The factors associated with inadequate pregnancy-related use of folic acid supplements in both countries will be investigated by multivariable regression analysis. Maternal age and anthropometric, socio-demographic and lifestyle factors will be considered in these analyses. The relationship between folic acid (timing of use and amount of consumption of folic acid supplements) and outcomes in child will be studied using multivariable regression analysis.