Objective (s): Food fortification is one of public health strategies to prevent and control anemia and iron deficiency. Flour fortification with iron and folic acid launched in 2001 in Iran. Thus the present meta-analysis conducted to assess the impact of flour fortification on hemoglobin, serum ferritin, anemia, iron deficiency and iron deficiency anemia.
Methods:
We searched English and Persian databases up to December 2013 to identify relevant studies. Quality assessment was conducted according to the EPOC (Cochrane Effective Practice and Organization of Care) statement. Meta-analysis was carried out using the Comprehensive Meta-Analysis version2 software. Random effects model was used due to the heterogeneity between the studies. Subgroup analysis and sensitivity analysis performed using CMA-2. Begg and Mazumdar’ Rank Correlation Test and Egger’s linear regression were adopted to test the possible publication bias.
Results:
A total of 42 articles (consisted 80 trials) were included in the study. Meta-analysis of “before-after studies” showed that flour fortification with iron resulted in a significant increase in hemoglobin levels (0.342 g/dl; 95% CI: 0.216 ~ 0.416, p<0.001) and serum ferritin levels (3.997 ng/ml; 95% CI: 1.782 ~ 6.213, p<0.001) and a reduced prevalence of anemia (-0.058; 95% CI: - 0.097 ~ - 0.018, p=0.005) and prevalence of iron deficiency (-0.073; 95% CI: - 0.114 ~ - 0.032, p=0.001) and no effect on iron deficiency anemia. Meta-analysis of “controlled trials” showed that flour fortification with iron resulted in a significant increase in hemoglobin levels (0.313 g/dl; 95% CI: 0.146 ~ 0.480, p<0.001) and serum ferritin levels (8.470 ng/ml; 95% CI: 6.694 ~ 10.246, p<0.001) and a reduced prevalence of anemia (-0.075; 95% CI: - 0.123 ~ - 0.027, p=0.002) and no effect on iron deficiency and iron deficiency anemia. Subgroups analysis indicated that the effectiveness of flour fortification with iron was reported more often in the before and after studies in "low quality" articles than in the controlled trials in "high quality" articles. Meanwhile, the use of NaFeEDTA was the most important factor in the effectiveness of flour fortification with iron.  
Conclusion:
The present meta-analysis provided evidence of the effectiveness of flour fortification with iron for improving hemoglobin and ferritin levels and reducing the risk of anemia. However, evidence of effectiveness for reducing the risk of iron deficiency was limited and there was no effect on iron deficiency anemia. It should be considered that controlled trials have provided more valuable results than before and after studies, and also chemical compound of iron was found to be an important factor in the effectiveness of flour fortification with iron.

Keywords: Flour fortification, Meta-analysis, Hemoglobin, Ferritin, Anemia, Iron deficiency, Iron deficiency anemia, Iran

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