WIC Participation and Dietary Quality among US Children: Impact of the 2009 Food Package Revision.

This study aims to assess the effectiveness of the WIC program at improving children's dietary quality and to evaluate whether the 2009 food benefit revision further improved the WIC program. A sample of 1,753 children aged between 2 to 4 years from the 2005-2008 and 2011-2016 NHANES was analyzed using a propensity score weighted difference-in-difference approach. Results show that WIC-participating children scored 2.98 points higher (SD: 0.89; P<0.01) in HEI-2015 total scores compared with income-eligible non-participants during 2011-2016. No significant change was observed in the differences of HEI-2015 scores between WIC participants and eligible non-participants from 2005-2008 to 2011-2016.