The role of curriculum dose for the promotion of fruit and vegetable intake among adolescents: results from the Boost intervention.

Thea Suldrup Jørgensen,Trine Pagh Pedersen,Sanne Ellegaard Jørgensen,Annette Kjær Ersbøll,Pernille Due,Mette Rasmussen,Elizabeth Goodman,Anne Kristine Aarestrup,Rikke Krølner

doi:10.1186/s12889-015-1840-0

Thea Suldrup Jørgensen, Trine Pagh Pedersen + Show 7 more

Open Access

https://doi.org/10.1186/s12889-015-1840-0

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Abstract

BackgroundMulti-component interventions combining educational and environmental strategies have proved effective in increasing children and adolescents’ fruit and vegetable intake. However such interventions are complex and difficult to implement and several studies report poor implementation. There is a need for knowledge on the role of dose for behaviour change and for assessment of intervention dose to avoid conclusions that intervention components which are not implemented are ineffective. This study aimed to examine 1) the association between dose of a class curriculum and adolescents’ fruit and vegetable intake in a school-based multi-component intervention, 2) if gender and socioeconomic position modify this association.MethodsWe carried out secondary analysis of data from intervention schools in the cluster-randomized Boost study targeting 13-year-olds’ fruit and vegetable intake. Teacher- and student data on curriculum dose delivered and received were aggregated to the school-level and class-level (only possible for student data). We analysed the association between curriculum dose and students’ (n 995) self-reported fruit and vegetable intake (24-h recall questionnaire) after finalization of the intervention using multi-level analyses. Potential moderation was examined by analyses stratified by gender and socioeconomic position.ResultsAverage dose received at class-level was significantly associated with students’ fruit and vegetable intake (10 g (CI: 0.06, 20.33) per curricular activity received). In stratified analyses the association remained significant among boys only (14 g (CI: 2.84, 26.76) per curricular activity received). The average dose delivered and received at the school-level was not significantly associated with students’ intake.ConclusionsWe found a dose—response relationship between number of curricular activities received and adolescents’ fruit and vegetable intake. The results indicate that curriculum dose received only mattered for promotion of fruit and vegetable intake among boys. Future studies should explore this gender difference in larger samples to guide the planning of school-based curricular interventions with regards to the optimal number of curricular activities required to promote behavioural change in subgroups with low fruit and vegetable intake at baseline.Trial registrationCurrent Controlled Trials ISRCTN11666034.

Highlights

Multi-component interventions combining educational and environmental strategies have proved effective in increasing children and adolescents’ fruit and vegetable intake
Previous studies have reported conflicting results on the association between dose delivered of dietary interventions and adolescents’ dietary behaviour change: The Pro Children Study and the Dutch Krachtvoer Healthy Diet Programme found a positive association between number of fruit and vegetables (FV) lessons delivered and changes in FV intake among 11-year-olds in Norway, Spain and the Netherlands [12] and 12–14-year-olds in the Netherlands [17], respectively
The literature suggests that girls in general respond better to school-based interventions addressing energy balance behaviour than boys [21], our results indicate that the dose of a curriculum is more important for changing boys’ FV intake

Summary

Introduction

Multi-component interventions combining educational and environmental strategies have proved effective in increasing children and adolescents’ fruit and vegetable intake. Such interventions are complex and difficult to implement and several studies report poor implementation. School-based multi-component interventions combining educational and environmental strategies have proved effective in increasing children and adolescents’ FV intake [3,4,5,6] Such interventions are complex and difficult to implement [7, 8] and several studies report poor implementation [9,10,11,12]. There is a need for more research on the role of dose of curricular interventions targeting adolescents’ FV intake including the role of curriculum dose received reported by students

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