Impact of Voluntary Folic Acid Fortification of Corn Masa Flour on RBC Folate Concentrations in the U.S. (NHANES 2011–2018)

Abstract

ObjectivesSurveillance data have highlighted continued disparities in neural tube defects (NTDs) among infants of Hispanic women of reproductive age (HWRA) in the United States. Starting in 2017, the US Food and Drug Administration implemented voluntary folic acid fortification of corn masa flour to reduce the risk of NTDs. We assessed folate status, using red blood cell (RBC) folate concentrations, in HWRA (aged 12–49 y) before (2011–2016) and after (2017–2018) voluntary fortification of corn masa, stratified by acculturation factors (i.e., primary language spoken at home, length of time residing in the US). MethodsCross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 2011–2018 with available RBC folate concentrations for HWRA were analyzed. Additional analyses were conducted among HWRA whose only folic acid source was fortified foods (enriched cereal grain products (ECGP) only), including usual intake and NTD prevalence estimations based on previously published models. ResultsOverall, RBC folate concentrations (adjusted geometric means) among HWRA remained similar from 2011–2016 to 2017–2018, though RBC folate significantly increased in 2017–2018 among lesser acculturated HWRA consuming ECGP only. Concentrations for those who were born outside the US and resided in the US < 15 y increased from 894 nmol/L (95% CI: 844–946) in 2011–2016 to 1018 nmol/L (95% CI: 982–1162; p < 0.001) in 2017–2018. Primarily Spanish speaking HWRA who consumed ECGP only increased from 941 nmol/L (95% CI: 895–990) in 2011–2016 to 1034 nmol/L (95% CI: 966–1107; p = 0.03) in 2017–2018. We observed no significant changes in the proportion at risk of NTD (<748 nmol/L) and no changes in Bayesian model-based estimated NTD rates. ConclusionsThis early analysis following voluntary corn masa fortification found an increase in RBC folate concentrations in lesser acculturated groups relying on fortified foods as their primary folic acid source, though HWRA overall had no significant increase in folate concentrations. These early data suggests that there is remaining risk among Hispanics for folate sensitive NTDs; continued monitoring of folate status with NHANES will help assess the long-term efficacy of voluntary fortification. Funding SourcesNo funding sources outside of salaries.