Average and distributional effects of the American Folic Acid Fortification: an evaluation in a quasi-experimental framework

Elena Fumagalli 2
1University of East Anglia, UK, 2Universita' Ca Foscari, Italy

The American program of folic acid fortification has increased the average amount of serum folate in the population and as such is deemed a successful public health intervention. We consider the effect of the fortification in a quasi experimental framework, evaluating also its distributional effects, to study the problem of folic acid overconsumption. We use several waves of the National Health and Nutrition Examination Survey (NHANES) to assess the effect of fortification on inequalities both in serum folate and in Vitamin C concentration, used as a proxy of the changes in nutritional habits. We find a reduction in inequality of both nutrients, thus suggesting that part of the increase in average serum folate concentration can be explained by changes in diet. We focus in particular on the effect of the consumption of fortified ready-to-eat cereals finding a strong selection into treatment mainly based on race-ethnicity. We compute the average treatment effect by using matching methods to solve the problem of selection on observables. In addition, we assess the impact of the fortification onr the entire distribution of the treatment by computing quantile treatment effects on serum folate concentration, both under the assumption of rank invariance and relaxing it. We find a significant variability in the impact distribution, thus rejecting the common effects model. Finally, we correct our estimates by controlling for the change in dietary patterns, using the concentration of beta-carotene as a proxy

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