Process and outcome evaluation of the school-based project "Students' enterprises for healthy nutrition"

Most food consumed in German schools is unhealthy, and evaluations of school-based interventions to improve food habits are scarce. Our study evaluates implementation and impact of "Students' Enterprises for Healthy Nutrition", in which students offer healthy food to their school mates. Standardised questionnaires were obtained from the supervising teachers and 923 students (grade 5-10) from the 4 intervention schools, collecting information on implementation and acceptability of the intervention (process evaluation). Data on eating habits were collected from a cohort of 475 students before and 6 months after the implementation of the Students' Enterprises, using a modified, illustrated version of a 24-hour-recall questionnaire (outcome evaluation). 59% of the students appreciated the Students' Enterprises, which varied substantially between schools, and 7-27% regularly purchased their food there. Reasons for not using the Student's Enterprises were food provision from home, peer pressure, and costs. Besides, there were competing sources of food supply in each school. Data interpretation was difficult due to the heterogeneity of the Students' Enterprises and reduced program integrity. A separate analysis of the different schools showed the reduction of sweets consumption in one school; other improvements of eating habits were not shown. The Students' Enterprises represent a peer-based settings approach and were supported by the students and teachers. Further structural changes and educational means are needed to increase utilisation. Due to demand, the Enterprises' menus risk to be extended to unhealthy food, which may be countered with innovative strategies (e.g. subsidy for healthy food).