title: Curricular activities and change in determinants of fruit and vegetable intake among adolescents: Results from the Boost intervention.
abstract: Knowledge of the association between implementation of different intervention components and the determinants they are tailored to change may contribute to evaluating the effects and working mechanisms of multi-component interventions. This study examined 1) the effect of a Danish multi-component school-based intervention (2010 - 2011) on key determinants of adolescents' fruit and vegetable intake and 2) if dose of curricular activities was positively associated with change in these determinants. Using multi-level linear and logistic regression analyses stratified by gender and socioeconomic position, we analyzed survey data from the cluster-randomized Boost study targeting Danish 13-year-olds' fruit and vegetable intake. We examined 1) differences in knowledge of recommendations, taste preferences and situational norms between students from 20 intervention (n=991) and 20 control (n=915) schools at follow-up; and 2) associations between curriculum dose received and delivered (student and teacher data aggregated to school- and class-level) and these determinants among students at intervention schools only. At follow-up, more students from intervention than control schools knew the recommendation for vegetable intake (OR 1.56, CI:1.18, 2.06) and number of fruits liked (taste preferences) increased by 0.22 (CI:0.04, 0.41). At class-level, curriculum dose received was positively associated with proportion of students knowing the recommendation for vegetable intake (OR 1.06, CI:1.002, 1.13). In stratified analyses, this association was only significant among students from high social class (OR 1.17, CI:1.04, 1.31). The Boost intervention succeeded in improving students' taste preferences for fruit and knowledge of recommendation for vegetable intake, but only the latter determinant was positively associated with curriculum dose.Trial registration:ISRCTN11666034.
authors.affiliation: Centre for Intervention Research in Health Promotion and Disease Prevention, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Thea Suldrup
authors.initials: TS
authors.lastname: Jørgensen
authors.affiliation: Centre for Intervention Research in Health Promotion and Disease Prevention, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Rasmussen
authors.affiliation: Centre for Intervention Research in Health Promotion and Disease Prevention, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Sanne Ellegaard
authors.initials: SE
authors.lastname: Jørgensen
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Annette Kjær
authors.initials: AK
authors.lastname: Ersbøll
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Trine Pagh
authors.initials: TP
authors.lastname: Pedersen
authors.affiliation: Centre for Intervention Research in Health Promotion and Disease Prevention, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Anne Kristine
authors.initials: AK
authors.lastname: Aarestrup
authors.affiliation: Centre for Intervention Research in Health Promotion and Disease Prevention, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Pernille
authors.initials: P
authors.lastname: Due
authors.affiliation: Centre for Intervention Research in Health Promotion and Disease Prevention, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 2nd floor, 1353 Copenhagen K, Denmark.
authors.forename: Rikke
authors.initials: R
authors.lastname: Krølner
keywords: Adolescents; Curriculum dose; Fruit and vegetable intake; Knowledge of recommendations; Process evaluation; RCT; School-based intervention; Situational norms; Taste preferences