Students' beliefs and behaviour regarding low-calorie beverages, sweets or snacks: Are they affected by lessons on healthy food and by changes to school vending machines?

Abstract

Objective To study the effects of school lessons about healthy food on adolescents' self-reported beliefs and behaviour regarding the purchase and consumption of soft drinks, water and extra foods, including sweets and snacks. The lessons were combined with the introduction of lower-calorie foods, food labelling and price reductions in school vending machines. Design A cluster-randomized controlled design was used to allocate schools to an experimental group (i.e. lessons and changes to school vending machines) and a control group (i.e. 'care as usual'). Questionnaires were used pre-test and post-test to assess students' self-reported purchase of extra products and their knowledge and beliefs regarding the consumption of low-calorie products. Setting Secondary schools in the Netherlands. Subjects Twelve schools participated in the experimental group (303 students) and fourteen in the control group (311 students). The students' mean age was 13·6 years, 71·5% were of native Dutch origin and mean BMI was 18·9 kg/m2. Results At post-test, the experimental group knew significantly more about healthy food than the control group. Fewer students in the experimental group (43%) than in the control group (56%) reported bringing soft drinks from home. There was no significant effect on attitude, social norm, perceived behavioural control and intention regarding the consumption of low-calorie extra products. Conclusions The intervention had limited effects on students' knowledge and self-reported behaviour, and no effect on their beliefs regarding low-calorie beverages, sweets or snacks. We recommend a combined educational and environmental intervention of longer duration and engaging parents. More research into the effects of such interventions is needed.