To determine whether Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food benefit redemption is associated with discontinuing WIC participation, failure to recertify, overall and by race/ethnicity-language preference and participant category.

Retrospective cohort study, using multivariable modified Poisson regression to determine risk ratios (RR) and 95 % CI for associations between household-level food benefit redemption (interval-scaled benefit redemption percent, averaged across WIC benefit subcategories, for the final 3, 6 and 12 months of certification) and failure to recertify in WIC, overall and within strata of race/ethnicity-language preference and participant category.

WIC administrative data collected November 2019–July 2021 in Southern California.

WIC-participating children ages 0–3 years at initial certification from November 2019 to May 2020 (n 41 263).

In all time periods, and for all subgroups, every 10 % lower food benefit redemption was associated with increased risk of failure to recertify. Among households without missing food benefit data, failure to recertify risk peaked at 505 % higher (RR = 6·05, 95 % CI (5·63, 6·51)) in households with average 12-month redemption <10 % compared with households with ≥70 % redemption.

Lower WIC benefit redemption was associated with higher risk of failing to recertify among participants. Focused nutrition education around benefit redemption may improve WIC retention and child health through incremental increases in food benefit redemption.

To use nationally representative data to evaluate changes in nutrient and food intakes among children and women participating in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) before v. after implementation of the 2009 food package revisions.

Cross-sectional study using National Health and Nutrition Examination Survey (NHANES) data. NHANES survey cycles were pooled to assess nutrient/food group intakes among household WIC participants pre- (2005–2008) v. post- (2011–2014) implementation of the 2009 food package revisions.

Information regarding WIC participation and 24 h diet recalls were collected at NHANES examination.

Children 24–59 months old and women 19–50 years of age in households receiving WIC benefits in the NHANES 2005–2008 and 2011–2014.

Comparison of WIC participants’ dietary intake pre- and post-revision demonstrated changes in mean population intakes of both nutrients and food groups. The food package revisions were associated with increased intakes of fibre (P = 0·004 children, P = 0·013 women) and whole grains (P = 0·001 children, P = 0·087 women). For children only, vegetable intake shifted to higher consumption of legumes (P = 0·013) and decreased intake of starchy vegetables (P = 0·042). No significant changes were observed for dairy or fruit intake of children or women.

The study provides insight to what goals of the package revisions were achieved. The findings can inform future food package revisions.