Pilot Study of a Farm-to-Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) Intervention Promoting Vegetable Consumption

Abstract

Background: Vegetable intake is below recommended levels among adults served by the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

Objective: The aim of this study was to determine whether a novel, theory-driven, farm-to-WIC intervention to promote vegetable intake showed promise of being successful and is therefore appropriate for efficacy testing.

Design: From June 2019 to January 2020, the intervention was piloted in three WIC agency sites (one randomized to the intervention study group and two to the control group) selected based on similarity in size and the demographics of participants served.

Participants/setting: Recruited between June 3, 2019 and August 1, 2019, participants were 297 primarily Hispanic adults served by a large WIC agency located in a densely populated urban area in New Jersey (160 were enrolled at the intervention site and 137 at control sites).

Intervention: The intervention combined behaviorally focused instruction and handouts with the introduction of a WIC-based farmers' market, field trips to an area farmers' market, telephone coaching and support before and after trips, and recipe demonstrations and tastings.

Main outcome measures: The primary outcomes were vegetable intake (measured objectively using dermal carotenoids as a biomarker of intake and via self-report) and the redemption of vouchers provided through the WIC Farmers' Market Nutrition Program (FMNP) for fruit and vegetable purchases at farmers' markets (objectively assessed using data provided by WIC).

Statistical analyses performed: Between-group differences in vegetable intake were examined at mid- and post-intervention (3 and 6 months post-baseline, respectively) with linear mixed-effects models adjusted for baseline vegetable intake and covariates. Logistic regression analysis was used to relate FMNP voucher redemption to study group and covariates.

Results: At mid-intervention, objectively measured vegetable intake was higher among participants in the control group as compared with the intervention group; self-reported intake did not differ by group. Post-intervention, objectively measured and self-reported vegetable intake were higher among participants in the intervention group as compared with the control group. Receipt of the intervention was associated with a greater likelihood of FMNP voucher redemption. Voucher redemption rates were 87% in the intervention group and 28% in the control group (odds ratio = 17.39, 95% confidence interval [8.64, 35.02]).

Conclusions: Meaningful associations found between the intervention, vegetable intake, and FMNP voucher redemption suggest that the program is appropriate for efficacy testing.

Trial registration: ClinicalTrials.gov NCT04038385.

Keywords: Farm-to-institution; Pilot study; Vegetable intake; WIC program.

Conflict of interest statement

Conflict of interest disclosure: No conflicts of interest were reported by the authors of this paper.

Copyright © 2021 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1.

Flow of 297 urban, WIC-enrolled adults through a pilot study of a farm-to-WIC intervention WIC indicates Special Supplemental Nutrition Program for Women, Infants, and Children; FMNP, Farmers’ Market Nutrition Program

Figure 2.

Logic model for a farm-to-WIC intervention to promote vegetable intake among urban, WIC-enrolled adults WIC indicates Special Supplemental Nutrition Program for Women, Infants, and Children; FMNP, Farmers’ Market Nutrition Program. Adapted with permission from Liberato SC, Bailie R, Brimblecombe J. Nutrition interventions at point-of-sale to encourage healthier food purchasing: a systematic review. BMC Public Health. 2014;14: 919.