Analyzing the Association between Flour Fortification and World-Wide Anemia Prevalence

Abstract

Objectives: The effectiveness of flour fortification in reducing anemia prevalence is equivocal. The goal of this study was to utilize existing data to assess whether anemia in non-pregnant women was reduced after countries began fortifying wheat flour, alone or in combination with maize flour, with at least iron, folic acid, vitamin A, or vitamin B12. Methods: Nationally representative anemia data were identified through DHS reports, the WHO-VMNIS database, and other national-level nutrition surveys.  Countries with at least 2 anemia surveys were considered for inclusion.  Within countries, surveys were excluded if data were not available for non-pregnant women, if altitude was not consistently adjusted for, or if both the site (e.g., capillary or venous) and method (e.g., HemoCue or Cyanmethaemoglobin) of blood draw differed. Anemia prevalence was modeled for countries that had pre-and post-fortification data (n=12) and for countries that never fortified flour (n=20) using logistic regression models that controlled for time effects, human development index (HDI), and endemic malaria. Results: Adjusting for HDI and malaria, each year of flour fortification was associated with decreased anemia prevalence by 2.5% (PR=0.975, 95%CI: 0.974, 0.976). Among countries that never fortified, no reduction in anemia prevalence over time was observed (PR=0.999, 95%CI: 0.997, 1.002). In both models, HDI and malaria were significantly associated with anemia (p<0.001). Conclusions: Evidence from national-level surveys suggests that after controlling for time effects, HDI, and endemic malaria, anemia prevalence has decreased significantly in countries that fortify flour with micronutrients, while remaining unchanged in countries that do not.