The United States implemented mandatory fortification of cereal grains with folic acid in 1998 to prevent neural tube defects (NTDs) during pregnancy. The health benefits of folate (vitamin B9) are well documented; however, there are potential risks of exceeding the upper tolerable limit, particularly in vulnerable populations. We conducted a population-based analysis of the Food Fortification Initiative dataset to determine the strength of the evidence regarding reports of decreased NTDs at the national level in response to mandatory folic acid fortification of cereal grains. We found a very weak correlation between NTD prevalence and the level of folic acid fortification, irrespective of the cereal grain fortified (wheat, maize or rice). Stratification of the data based on socioeconomic status (SES) indicated a strong linear relationship between reduced NTDs and better SES. We conclude that national fortification with folic acid is not associated with a significant decrease in the prevalence of NTDs at the population level.
Keywords: Food Fortification Initiative; folate; methylenetetrahydrofolate reductase (MTHFR); national fortification; neural tube defect; vitamin B12; vitamin B9.