OBJECTIVES : The effect of the Women, Infants and Children (WIC) program on children's diet quality during early life is largely unknown primarily due to the selection problem polluting the estimation of treatment effects. In this research, we used novel data from a longitudinal prospective cohort study conducted in Shelby County, TN, to estimate the impact of WIC on Healthy Eating Index-2010 (HEI-2010) in children up to two years of age.

METHODS : This cohort study collected repeated measurements on WIC participation, and HEI-2010 dietary outcomes for a large sample of children and mothers. Exposure-outcome relationship were directly observable over time up to two years of age. This specific structure of the data and the evidence we provide enabled us to address self-selection concerns via the use of fixed effects estimators combined with a rich set of time-varying covariates.

RESULTS : Using robust empirical methods, we found that WIC participation was associated with a statistically significant increase in HEI-2010 total scores of 4,652 points (roughly 0.4 standard deviations). WIC improved dietary outcomes for seafood and plant protein, refined grains and decreased sodium intake..

CONCLUSIONS : Overall, reported results suggest that policymakers can improve dietary choices during critical and sensitive periods in human development through targeted policy interventions aimed at children from low income groups.