Availability and consumption of ultra-processed foods in schools in the municipality of São Paulo, Brazil: results of the SP-Proso.

Ultra-processed foods are markers of unhealthy eating patterns, and their consumption is high among adolescents. Characteristics of the school eating environment associate with student eating practices. This study aims to investigate the association between the presence of school canteens and the availability of ultra-processed foods in school canteens with the consumption of these foods, inside the school, among adolescents of the 9th grade (14 years) of the public and private schools of the city of São Paulo, Brazil. We conducted a cross-sectional study with SP-Proso data, in a sample of 2,680 adolescents. We elaborated multilevel linear regression models to evaluate associations between the exposures: presence of school canteens and availability of ultra-processed foods with outcomes of consumption frequency of ultra-processed foods in the school. We found an association between the presence of school canteens and the higher frequency of consumption of sausages (0.46; 95%CI: 0.24; 0.68), package snacks (0.50; 95%CI: 0.19; 0.80), goodies (0.82; 95%CI: 0.55; 1.09), and sugary drinks (0.34; 95%CI: 0.06; 0.62), as well as a score of consumption frequency of ultra-processed foods (2.37; 95%CI: 1.25; 3.48). The availability of package snacks, goodies, and sugary drinks in school canteens increased the frequency of consumption of these foods. We observed a dose-response effect between the diversity of ultra-processed foods in canteens and the frequency of consumption of these foods. A school food environment with greater availability of ultra-processed products is associated with their higher consumption in school, indicating the need to regulate the sale of food within these institutions.