Examining the Association Between an Increase in the WIC Fruit and Vegetable Benefit and WIC Participant Food Purchases

Background

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides nutritious foods to more than six million low-income families in the US. In June 2021, WIC substantially increased the amount of money provided for fruits and vegetables (FV), but studies have not investigated changes in WIC participant FV purchases after the increase using food purchase data.

Objective

Estimate the association between the FV funding increase and WIC shoppers’ FV purchases.

Study Design, Settings, Participants

This study used longitudinal food purchase data from 496 stores in a grocery store chain in North Carolina between June 2020 and April 2022. A propensity score weighted difference-in-differences (DID) approach was used to estimate the effect of the FV benefit increase among WIC shoppers (n=536,349 shopper-month observations) relative to non-WIC comparison shoppers (n=1,894,056 shopper-month observations) matched on pre-benefit change shopping patterns.

Measurable Outcome/Analysis

Primary outcomes were monthly dollar expenditures and ounces purchased of WIC-eligible fruits, nutrient-dense vegetables, and starchy vegetables. Secondary outcomes included unique varieties of FV purchased and ounces purchased of processed foods and sugar-sweetened beverages. Propensity-score weighted two-part models and zero inflated negative binomial models were used to estimate the association between the FV funding increase and monthly food purchases.

Results

WIC shopper WIC-eligible FV purchases increased by $12.4 per shopper per month (Confidence Interval (CI), $12.0 to $12.9) after the CVB increase, which was $9.3 (CI, $8.7 to $10.0) more than non-WIC shoppers. The volume and unique varieties of FV purchased also increased more among WIC shoppers relative to non-WIC shoppers (DID 67.1 ounces (CI, 61.9 to 72.3) and DID 2.1 varieties (CI, 2.0 to 2.3)). There were also increases in the volume of processed foods (DID 22.0 ounces (CI, 17.2, 26.9)) and sugar-sweetened beverages (DID 49.1 ounces (CI, 33.4, 64.9)) purchased among WIC shoppers.

Conclusions

Increased WIC FV funding was associated with greater FV purchases among WIC shoppers. These results can inform permanent changes to the FV component of the WIC food packages.

Funding

NIH, Arnold Ventures