Krølner et al. BMC Public Health 2012, 12:191 http://www.biomedcentral.com/1471-2458/12/191 Page 5 of 25 Determinants of FV intake Pupils’ intake of FV Boost intervention programme Implementation degree: dose delivered and received, fidelity Changes in proximal outcomes: Environmental determinants: availability at home, school and local community/leisure time activities Social determinants: Parent-, peer-, teacher- and sports coach influence (knowledge, attitude, intake, modelling, perceived barriers), social norms (situational norms, peer norms) Personal determinants: knowledge, awareness, taste preferences, short term outcome expectations Changes in unintended adverse outcomes: Bullying, weight- and eating related teasing, school class thriving, replacement of FV eaten at other times of the day Moderators: Gender Socioeconomic position Changes in distal outcomes: Pupils’ intake of FV Potential positive side-effects Energy for academic achievement, improved concentration during class lessons, increased wellbeing, decreased intake of unhealthy snack- food Maintenance of changes in distal outcomes: Pupils’ intake of FV Potential positive side- effects at the school level: Sustained environmental changes and capacity building Figure 1 Programme theory of the hypothesised causal relationship between the Boost intervention programme, proximal and distal outcomes and side-effects. Assessment of adverse effects is often neglected in effec- tiveness studies [58]. It is relevant to explore whether intervening in the adolescents’ life produces any unin- tended adverse effects as suggested in Figure 1. Eating behaviours may be a vulnerable issue among teenagers and we paid special attention to this in the development of project logo and curricular activities. We did not want to contribute to promotion of a certain body image or discri- mination of certain groups e.g. adolescents with over- weight problems or unhealthy eating habits. Also we did not want to exhibit low income families in curricular activ- ities. For instance, home assignments on exploring the FV supply at home and monitoring parents’ and siblings’ FV intake for a week were not planned for class discussion, but for discussion within the family only. Matrices (step 2) In step 2 we aimed at developing a comprehensive inter- vention reaching all important determinants specified in the programme theory (Figure 1). Matrices were created according to the Intervention Mapping protocol and change objectives were decided. Tables 1, 2 display a small section of two of the educational and environmen- tal change objectives. Design of intervention programme (step 3 + 4) Step three included the final decisions about the inter- vention programme and its components. The matrices guided the selection of theoretical methods and practi- cal applications to achieve each change objective (see Tables 1 and 2 for some examples) [51,59]. In agree- ment with recommendations for best practice we used theoretical methods from a variety of theories such as social cognitive theory, theories of information proces- sing, health belief model, and the socio-ecological fra- mework [51,60]. Programme activities focused on increasing the adolescents’ access to FV in schools, families and sport/youth clubs and on reduction of