Abstract / Summary
Abstract Background The school food environment significantly influences students’ dietary habits. Adolescents consume approximately one-third to one-half of their meals at school, rendering this a critical context for interventions to improve the food environment. The off-campus food environment also plays a critical role in shaping dietary behaviors, particularly in schools with open-campus policies; greater access to fast-food restaurants and convenience stores is associated with increased consumption of energy-dense, nutrient-poor foods. This systematic review aims to synthesize literature examining associations between open-campus policies or lunch food source and dietary behaviors among high school students (at least 9th grade; aged 12 + years). Methods In this systematic review (without meta-analysis), a comprehensive literature search was conducted using PubMed, Scopus, Agricola, and Education Full Text, following PRISMA guidelines. Inclusion criteria included: peer-reviewed quantitative studies published in English between 1990 and 2024 that assessed associations between open/closed-campus policies or lunch food source (on- or off-campus) and dietary habits, or lunch policies aimed at keeping students in school for meals and dietary habits. Data extraction was conducted, and study certainty was assessed using the Effective Public Health Practice Project tool. Results A total of 4,747 articles were imported into Rayyan software. After removing duplicates, 3,708 article titles and abstracts were screened; 14 full-text article screens resulted in five studies that met the eligibility criteria. Two eligible studies were identified through reference list screening, bringing the total number of included studies to seven. Of the seven included studies, five employed a cross-sectional design, one used a quasi-experimental design, and one was a cohort study. Findings reveal a consistent association between open-campus policies and students acquiring lunch from external food outlets during the school day, and with less healthy dietary behaviors. Conclusions Limitations include protocol constraints like the exclusion of gray literature, as well as limitations in the evidence base itself, which consisted of seven studies of predominantly moderate-to-weak certainty. However, overall findings underscore the potential of school lunch policies, including closed-campus models, as an intervention to mitigate the impact of unhealthy external food environments on adolescent dietary behaviors.