This study is a longitudinal controlled trial that is designed to investigate the effectiveness of a multi-component intervention on improving fruit and vegetable consumption in teenagers and their mothers. Participants will be allocated in three groups with a) an intervention group in which mothers and children receive the intervention and questionnaires, b) only the children receive the intervention and mothers and children receive the questionnaires, and c) mothers and children are in active control group and only receive the questionnaires. The intervention package contains behavior change techniques targeting outcome expectancy, self-efficacy, action planning, coping planning, and self-monitoring. The active control group receives an information sheet regarding recommendations on fruit and vegetable intake. There will be 3 assessment points in time, with 1 months in between. All the intervention materials and information sheets will be handed to participants after the baseline assessment. The self-monitoring calendar will be collected at time 2 assessment.
The primary outcome of this study is to estimate the dyadic mechanisms between mothers and their children regarding improving fruit and vegetable intake. Secondary outcome is to investigate whether fruit and vegetable consumption did improve in the intervention groups in general and also to find the psychological mechanism behind the changes during the time of the study.
