Nutritional Anemia Reductions Due to Food Fortification Among Women of Childbearing Age: A Literature Review and Bayesian Meta-Analysis.

Food fortification can deliver essential micronutrients to populations at a large scale, thereby reducing nutritional anemia. This study aimed to review and meta-analyze the literature on the impact of wheat flour, maize flour, rice, and oil (singly or combined) fortification on women's (10-49 years) hemoglobin and anemia. A search of 17 databases yielded 2284 results. Longitudinal, pre-post cross-sectional, efficacy, and effectiveness studies were included. Primary outcomes were changes in hemoglobin concentration and anemia prevalence. Studies were synthesized using arm-based network meta-analysis. In women who consumed fortified rice, hemoglobin mean change was 3.24 g/L (95% credibility interval (CrI) 0.9, 5.98), higher than for women in the control, with a 99.1% probability that the true mean difference was > 0. Hemoglobin was 2.08 g/L (95% CrI -0.76, 4.35) higher in women who consumed wheat flour versus control, with a 93.5% probability that the true mean difference was > 0. After rice fortification, anemia prevalence in women was 1.38 percentage points (95% CrI -106.6, 99.2) lower than for control women, with a 51.2% probability that the true mean difference was < 0. Wheat flour fortification decreased anemia prevalence by 1.84 percentage points (95% CrI -93.4, 92.4) with a 52.72% probability that the true mean difference was < 0. The treatment effects of fortified maize flour and fortified oil could not be calculated due to the absence of control arms compared to the intervention arms. Fortified rice and wheat flour appear likely to modestly increase hemoglobin and may also reduce anemia in women of childbearing age.