Page 89 - ON THE WAY TO HEALTHIER SCHOOL CANTEENS - Irma Evenhuis

making more research needed.
Changing dietary behaviour is complex and affected by multiple individual, social and environmental factors [15, 41, 189]—for example, the palatability, price and convenience of foods offered in environments that youth visit regularly, including the school canteen and shops around schools [15, 17, 19]. During adolescence, many factors that influence youth’s dietary choices are changing: they become more independent, parental influence decreases and influence of peers increases, living environments expand, and they have more money to spend [190, 191]. These changes provide opportunities to develop healthy dietary habits which are likely to sustain over time [10]. Even though our study did not show a relation between a healthier canteen and healthier purchase behaviour, we would recommend that healthier food choices should be facilitated in school canteens, including vending machines, a place that students visit regularly and where students can autonomously choose what they buy. This might influence student purchase behaviour directly at the school canteen or in shops around schools, and foresees in educating adolescents on healthy norms [192]. This enables all youth to experience that healthy eating is important, tasty and very common, which they can use throughout their life.
A strength of our study is that the support consisted of multiple implementation tools which 5 stakeholders could decide to use, as well as when and how. Moreover, our study included
tailored advice. Previous research has shown that both a combination of components and
tailored advice could increase the likelihood of an effective implementation plan [56, 193].
Other strengths of our study are the measurement of outcomes both on the canteen and student level and the separate analyses for boys and girls. In general, boys are more likely to make impulsive, intuitive changes [25]. In contrast, girls are more likely to overthink their choices, limiting the effect of an attractive food offering. In our study, subtle differences across gender were observed, with boys indicating buying food and drinks outside the school more often. However, this finding should be further explored in future studies.
There are also some study limitations that should be mentioned. First, the use of self- reported questionnaires to investigate purchase behaviour. These measurements are potentially subject to reporting bias and socially desirable answers, likely leading to smaller number of reported purchases overall and larger number of reported healthier products. Possibilities to measure the dietary behaviour of student more objectively and regularly include, for example, the use of meal observations, sales data or Ecological Momentary Assessment (EMA) [194, 195]. We could not use these options due to feasibility constraints, e.g., making use of sales data was not possible as due to different registration systems. Another limitation is the study duration, which was four to six months. A study duration of at least one school year will align to the schools’ daily practice and will give schools the opportunity to create a team of involved people, to embed actions and to make changes.
The fact that the intervention was individualized to the contextual factors and needs of each school is both a strength and limitation. Alignment of the advices to a school’s situa- tion might lead to a more useful support but can also make it more difficult to compare re- sults between different intervention schools. Therefore, it is important to (1) describe the core intervention functions of each tool of the implementation plan to be able to support schools with the same support and (2) to measure if the tools has been delivered and used as
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