Salad bars and students' fruit and vegetable consumption: A group-randomized trial with objective assessments

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Abstract. Building healthy fruit and vegetable (FV) consumption habits early in life are critical for primary prevention of diseases such as cancer and cardiovascular disease. However, youth in the US do not come close to meeting the national recommendations for FV intake. Given that youth consume 1/3-1/2 of their dietary intake in schools and the school meals program serves over 30 million children, major efforts have been made to improve access and subsequent consumption of FVs through the passage of the Healthy Hunger Free Kids Act. Salad bars are one of the most heavily promoted ways to meet the FV regulations in the Healthy Hunger Free Kids Act as a means to increase student FV intake. Let's Move Salad Bars to School, an arm of Let's Move!, Michelle Obama's obesity prevention initiative, has already instituted over 4715 salad bars in schools, with the goal of having a salad bar in every single school, an investment of millions of dollars. Contrary to popular belief, to date, just a single quasi-experimental study has evaluated the efficacy of implementing school salad bars for increasing FVs; this study was conducted with only elementary students from one school district. No studies have examined whether implementing salad bars in middle or high schools increase students' FV consumption. Grounded in the conceptual framework of behavioral economics, the purpose of this study is to examine whether introducing salad bars in elementary, middle, and high schools that have never had salad bars affects students' FV consumption and waste during lunch. A cluster randomized controlled trial will test new salad bars against wait-list controls for 6 weeks, with and without an additional 4- week marketing phase (N=36 schools, N=6804: n=12 elementary, n=12 middle and n=12 high schools). Plate waste measurements of students' selection of FVs and waste will be used to objectively estimate consumption. The primary aim of this study is to compare FV consumption in schools without salad bars to those with new salad bars by grade level (i.e., elementary, middle, high). We hypothesize that students' FV consumption will be greater in schools that implement salad bars. We will examine three secondary aims: a) how FV marketing impacts the success of salad bars at changing FV consumption. We hypothesize that marketing will help to increase FV consumption; b) assess whether salad bars differentially result in more FV plate waste compared to traditional serving methods; c) test the cost-benefit of using salad bars for FV consumption over traditional serving methods in order to provide better evidence to over 100,000 schools serving meals to children participating in the National School Lunch program. A tertiary aim is to examine how salad bar location (inside service line before point of purchase vs. outside service line) is related to FV intake. When the aims of this study are complete, this project stands to be one of the most definitive studies to date on the efficacy of salad bars in schools and contextual factors that promote their success. Findings will provide evidence for how to best spend limited federal dollars to improve FV intake in schools.