A Randomized Controlled Trial of the Food Dudes Program: Tangible Rewards are More Effective Than Social Rewards for Increasing Short- and Long-Term Fruit and Vegetable Consumption

Abstract

Background: Despite many health benefits, children do not consume enough fruits and vegetables (F/V). The Food Dudes program increases in-school F/V consumption, but the cost of prizes might be an adoption barrier.

Objective: Our aim was to compare the effects of the Food Dudes program when prizes vs praise are used to reward F/V consumption.

Design: We conducted a randomized controlled trial with three groups (ie, prize, praise, and control). Schools were randomly assigned to groups while approximately equating the percentage of students qualifying for free or reduced-price lunch. F/V consumption (lunch-tray photos) was assessed twice at pre-intervention and once after phase I, phase II, and at 6 months post-intervention, spanning approximately 11 months overall.

Participants/setting: In total, 2,292 students attending six elementary schools participated, with 882, 640, and 770 in the prize, praise, and control groups, respectively.

Intervention: The Food Dudes program was implemented over 4.5 months in all but the control schools. Two Food Dudes schools implemented the program with tangible prizes contingent on individual students' F/V consumption (prize group); two schools implemented Food Dudes using teacher praise instead of prizes (praise group). Follow-up data were collected 6 months post-intervention.

Main outcome measure: F/V consumption was assessed by digital imaging of lunch trays.

Statistical analysis performed: Linear mixed-effects modeling, including sex, grade, and baseline consumption as covariates, was performed.

Results: Students attending the Food Dudes schools consumed more F/V than control schools after phase I, with larger differences in prize schools (92% difference) than praise schools (50% difference). After phase II, Food Dudes schools consumed 46% more F/V than control schools, with no difference between prize and praise schools. At 6-month follow-up, only prize schools consumed more F/V than control schools (0.12 cups more per child, 42.9% difference).

Conclusions: Social praise proved an inadequate substitute for tangible prizes within the Food Dudes program. Program-related increases in F/V consumption decreased after the intervention, underscoring the need to develop low-cost, long-term interventions to maintain and make habitual consumption of recommended levels of F/V.

Keywords: Elementary school; Food Dudes; Fruit and vegetable consumption; Incentives; Long-term effects.