Estimate of the potential impact of folic acid fortification of corn masa flour on the prevention of neural tube defects.

Abstract

Hispanics in the US have a higher prevalence of neural tube defect (NTD) -affected pregnancies than non-Hispanic whites, and lower median total folic acid (FA) intake. FA fortification of corn masa flour (CMF) is a policy-level intervention for NTD prevention; however, the impact on NTD prevalence has not been estimated. We developed a model to estimate the percentage reduction in prevalence of spina bifida and anencephaly (NTDs) that could occur with FA fortification of CMF. Model inputs included estimates of the percentage reduction in United States NTD prevalence attributed to FA fortification of enriched cereal grain products (1995-1996 vs. 1998-2002), the increase in median FA intake after enriched cereal grain product fortification, and the estimated increase in median FA intake that could occur with CMF fortification at the same level as enriched cereal grain products (140 μg/100 g). We used Monte Carlo simulation to quantify uncertainty. We stratified analyses by racial/ethnic group and rounded results to the nearest 10. We estimated CMF fortification could prevent 30 Hispanic infants from having spina bifida (95% uncertainty interval: 0, 80) and 10 infants from having anencephaly (95% uncertainty interval: 0, 40) annually. The estimated impact among non-Hispanic whites and blacks was smaller. CMF fortification with FA could prevent from 0 to 120 infants, with the most likely value of approximately 40, from having spina bifida or anencephaly among Hispanics, the population most likely to benefit from the proposed intervention. While this estimated reduction is unlikely to be discernible using current birth defect surveillance methods, it still suggests an important benefit to the target population.