Examining the Role of the School Food Environment in Moderating Sugar-sweetened Beverage Consumption Among Adolescents in Alberta and Ontario, Canada: Cross-sectional and Longitudinal Evidence from the COMPASS Study

Abstract

Adolescents represent the greatest consumers of sugar-sweetened beverages (SSBs) in Canada, which is concerning, given the numerous adverse health outcomes associated with frequent SSB intake. Provincial school nutrition policies represent one population-level strategy intended to promote healthy dietary choices among Canadian youth. Both the Alberta Nutrition Guidelines for Children and Youth (ANGCY) and Ontario’s Policy/program Memorandum no. 150 (P/PM 150) recommend restrictions in SSB availability in school food outlets (e.g., cafeterias, vending machines, etc.) to decrease students’ access to products. There exists a broad range of contextual factors outside of schools that influence youths’ dietary choices; influences within other environments (e.g., the home, community, and larger regulatory contexts) can support or undermine school-based interventions, and should be accounted for in the development and evaluation of these initiatives. This dissertation research used the socioecological model as a theoretical framework to examine the role of the school context in influencing Canadian adolescents’ SSB intake in Alberta and Ontario. The objectives were to (i) characterize Canadian adolescents’ SSB consumption patterns; (ii) describe school food environment characteristics in Canadian secondary schools; (iii) describe how these characteristics reflect school-level compliance with provincial school nutrition policies; (iv) identify associations between school food environment characteristics and measures of students’ SSB intake; and, (v) identify potentially promising contexts and/or strategies for future population-level initiatives to reduce adolescents’ SSB intake. Three manuscripts served these objectives using student- and school-level data from the COMPASS study. The first two manuscripts represent cross-sectional analyses (2013/14), while the third manuscript includes longitudinal analyses (2013/14 to 2015/16). The first manuscript examined how several food purchasing behaviors (i.e., sources of meals/snacks) within and outside of the school context are associated with adolescents’ SSB consumption, and whether these associations vary by province. This study identified that most of the food purchasing behaviours were significantly and positively associated with greater rates of SSB consumption. Meal/snack purchases on weekends (versus weekdays) and from food outlets off-school property (versus on-school property) had a greater association with SSB consumption. The research identified a significantly higher rate of SSB intake among Albertan participants and a number of interesting interaction effects between province and various food purchasing behaviours, providing evidence that students’ rate of SSB intake may be related to differences in provincial school nutrition policies. The second manuscript provided a scoping assessment of several characteristics of the secondary school food environment (i.e., comprising features of the school and school neighbourhood) in Alberta and Ontario, provincial differences across these school characteristics, as well as whether these characteristics are associated with students’ SSB consumption rate. This study identified that participants had access to several potential sources of SSBs during their time in school; most schools were within walking distance of one or more external food outlets and a considerable proportion of schools stocked various types of SSBs in their vending machines. SSBs were significantly less available in Ontario schools’ vending machines compared to those in Alberta, suggesting that P/PM 150 is more effective than the ANGCY at restricting SSB availability in school vending machines. Few of the school food environment characteristics assessed were significantly associated with students’ SSB intake. The third manuscript examined changes in product availability within secondary schools’ beverage vending machines, changes in students’ weekday intake of SSBs over time, and the associations between these measures of beverage availability and SSB intake. Schools were separated into three policy groups: ‘Alberta’; ‘Ontario public schools’; and, ‘Ontario private schools’. Most SSB types examined were least available in Ontario public schools’ vending machines across all time points. Generally, vending machine beverage availability did not vary significantly over time. Across all policy groups, participants’ rate of soft drinks consumption decreased as they progressed through secondary school, while their intake of sweetened coffees/teas increased; other SSB outcome measures remained fairly stable. Students in Alberta reported the greatest frequency of SSBs intake across all time points and measures. There was limited evidence that changes in vending machine beverage availability was significantly associated with students’ SSB consumption. This dissertation enhances our current understanding of Canadian adolescents’ SSB intake patterns, the Canadian secondary school food environment, and the successes and shortcomings of school nutrition policies. This work signals the need for continued efforts to reduce adolescents’ SSB intake. This dissertation illustrates that the school food environment represents a source of SSBs for Canadian adolescents, since most schools are nearby external food outlets and many schools have SSBs available for sale within school vending machines. However, this research highlights that schools are one of many contexts that influences adolescents’ dietary behaviours, and efforts to limit the in-school availability of SSBs in vending machines have a limited impact on measures of adolescents’ SSB intake. This research signals the need for school-based interventions to be supported by parallel population-level initiatives that encourage healthy dietary choices among Canadians.