School environment and adherence to school meals among Brazilian public-school adolescents

Objective: To assess whether the school environment is associated with adherence to school meals among adolescent students in Brazilian public schools. Methods: Data from the 2015 National School Health Survey were analyzed. The provision of school meals was assessed according to student report and adherence through the frequency of weekly consumption, classified as adherence (≥3x/week), unsatisfactory adherence (≤2x/week), and non-adherence (none). The following characteristics of the school environment were considered: availability of a properly functioning kitchen and dining hall, cafeteria, and alternative outlets inside or outside schools, and sale of unhealthy food in the cafeteria and alternative outlets. Prevalence estimates were calculated considering the sample’s complex design. Results: 86.5% of public schools offered school meals, to which 31.3% of students adhered, 37.9% had unsatisfactory adherence, and 30.8% did not adhere to school meals. Adherence to school meals was higher among schoolchildren in the Midwest Region, from non-capitals, and rural area, while less adherence was observed among students from schools with a cafeteria, an alternative food outlet, and a cafeteria selling soft drinks. Conclusions: Low adherence to school meals is associated with the school geography and food environment. These results can support the formulation of actions to improve the school environment and help the universality of participation in the School Nutrition and Food Policy.


INTRODUCTION
Eating habits acquired in childhood and adolescence generally remain in adulthood 1,2 . High consumption of ultra-processed foods and low consumption of fruits and vegetables prevail among Brazilian adolescents, which is considered a significant risk factor for the early onset of obesity and other chronic non-communicable diseases, bringing serious repercussions in adulthood 1,3 , and contributing negatively to school performance 4 .
The environment has a significant influence on the eating habits of adolescents, emphasizing the school environment 5 because students remain at school for a considerable period of the day in most countries. Thus, at least one daily meal is consumed at school 6,7 . However, while the school is a strategic place for promoting healthy eating habits 8 , students are predominantly exposed to the sale of unhealthy foods in the school food environment 9,10,11,12 . According to the Food and Agriculture Organization of the United Nations (FAO), the school food environment corresponds to the available spaces and infrastructure where food can be obtained, purchased, or consumed in and around schools. Thus, depending on the availability, access, and types of food sold, this environment can be an essential factor in obesity in children and adolescents 13 .
In Brazil, in order to meet student nutritional needs during their school stay, public schools provide food to all students of primary education throughout the school year under the National School Feeding Program (PNAE), which, in turn, aims to contribute to the growth, biopsychosocial development, learning, and academic performance of students, and promote the consolidation of healthy eating habits, through food and nutrition education interventions 14 . Brazilian students can benefit from one or up to three meals a day, depending on their age and how long they stay in school, and the distribution times are defined by the responsible technical nutritionist 15 . However, the achievement of this program's objectives may be impaired due to the low adherence to school meals among adolescents, ranging from 20 to 60% 16,17,18,19,20,21,22 .
Considering that the food environment of Brazilian schools has obesogenic features 9,10,11,12 and that this may be contributing to low adherence to school meals 17,22 , this study aims to evaluate adherence to school meals according to the characteristics of the school environment among adolescent students in Brazilian public schools.

METHODS
This is a descriptive, cross-sectional study with data from the 2015 National School-based Health Survey (PeNSE), through a partnership between the Brazilian Institute of Geography and Statistics (IBGE) and the Ministry of Health, with support from the Ministry of Education. The study was approved by the National Research Ethics Commission (CONEP), on March 30, 2015 (registration Nº 1.006.467).
PeNSE is carried out every three years. However, the 2015 edition is the last available. Study data were obtained through a survey carried out with 9th-grade school students enrolled in the 2015 school year and regularly attending public and private schools in urban and rural areas throughout the national territory. The sample size allowed us to estimate the parameters for each of the 26 states and the Federal District, including capitals and municipalities in the Brazilian inland region. More detailed information on sample size can be found in another publication 23 .
Data were collected from April to September 2015 using a smartphone containing a structured and self-administered questionnaire divided into thematic modules. For this study, questions related to geographical characteristics, the school's administrative type, and food were used. PeNSE 2015 evaluated a total of 102,072 students frompublic (81,154) and private schools (20,918). However, considering that this study aimed to assess adherence to school meals for students RESUMEN Objetivo: Evaluar si el ambiente escolar está asociado con la adherencia a las comidas escolares entre los estudiantes adolescentes de las escuelas públicas brasileñas. Métodos: Se analizaron datos de la Encuesta Nacional de Salud Escolar de 2015. La provisión de comidas escolares se evaluó de acuerdo con el informe del estudiante y la adherencia a través de la frecuencia de consumo semanal, clasificada como adherencia (≥3x/semana), adherencia insatisfactoria (≤2x/semana) y no adherencia (ninguna). Las características del entorno escolar consideradas fueron: la disponibilidad de una cocina y comedor, quiosco y punto alternativo de venta de alimentos dentro o en la entrada de la escuela, y la venta de alimentos no saludables en el quiosco y en los locales alternativos. Las estimaciones de la prevalencia se calcularon considerando el complejo diseño de la muestra. Resultados: 86.5% de las escuelas públicas ofrecieron comidas escolares, a las cuales se adhirió 31.3% de los estudiantes, 37.9% tuvo adherencia insatisfactoria y 30.8% no se adhirió a las comidas escolares. La adherencia a las comidas escolares fue mayor entre los escolares de la Región Centro-Oeste, de las no capitales y del área rural, mientras que se observó una menor adherencia entre los estudiantes de las escuelas con cafetería, un punto de venta de comida alternativa y una cantina que vende refrescos. Conclusiones: La baja adherencia a las comidas escolares se asocia con variables geográficas de la escuela, así como con el entorno alimentario escolar. Por tanto, estos resultados pueden apoyar la formulación de acciones que tengan como objetivo mejorar el entorno escolar y ayudar a la universalidad de la asistencia a la Política de Nutrición y Alimentación Escolar. Palabras clave: Adolescentes; Comidas; Escuelas; Encuesta basada en la escuela; Política pública. served by the National School Feeding Program (PNAE), namely, those enrolled in the public primary education network 14 , only public schools that offered school meals were analyzed (67,881).
The provision of school meals was analyzed through the question, "does your school offer food (school meals/ lunch) to students in your class?" answered by students. Adherence to school meals was assessed based on the question "do you usually eat the food (school meals/lunch) offered by the school?", with answers categorized into: (1) adherence: "yes, every day"; and "yes, 3 to 4 days a week", (2) unsatisfactory adherence: "yes, 1 to 2 days a week" and "rarely" and (3) non-adherence: "no".
The following variables were considered for geographical characteristics and school's administrative type: school's administration type (federal, state, and municipal); regions (North, Northeast, Southeast, South, and Midwest); federative units; school's municipality type (capital and non-capital) and school's geographical location (urban and rural).
The school environment was assessed by a questionnaire answered by school principals. The selected questions were: (1) Does the school have a kitchen in good condition? (2) Does the school have a dining hall in good condition? (3) Does the school have a cafeteria? (4) Are there alternative outlets selling food products inside or at the school's entrance? (e.g., street vendor). All of these questions established dichotomous variables ("yes" and "no"). The following answer options were available for questions regarding the kitchen and cafeteria: "there is no kitchen", and "there is no cafeteria". Therefore, these answers were grouped in the "no" category.
Schools that had a cafeteria and an alternative outlet were evaluated for the sale of the following foods: soft drinks, sugar-sweetened beverages, fried salty snacks, bagged salty snacks (processed), biscuits or cookies (salty or sweet), and sweets (sweets, candies, chocolate, and others). These foods were selected from the food groups frequently available in cafeterias and alternative points of sale 23 and considered ultra-processed foods per NOVA classification 24 . Brazilian adolescents mainly consume these foods 25,26,27 , and the sale of these foods in the school environment is positively associated with their intake among adolescent students 10 .
Percentages of adherence to school meals and their respective 95% confidence intervals (95% CI) were estimated according to the geographical characteristics, school administration type, and characteristics of the school environment. The bivariate association was identified by the non-overlapping of the intervals. The SPSS version 23.0 for Windows was used to perform the analyses, considering the sample's complex design.

RESULTS
Of the 81,154 public schools included in the study, 86.5% offered school meals in 2015. The percentage of students benefited by the provision of school meals was higher in state (88.0%; 95% CI: 87.0; 89.0) compared to  Table 2).
Almost half of the students attended public schools with a cafeteria that sold soft drinks (41.9%; 95% CI 33.7; 50.5). Also, adherence to school meals was significantly lower in this group (21, 2%; 95% CI 17.6; 25.3) than those in schools with a cafeteria that did not sell soft drinks. Of the students with access to the cafeteria inside the school, 30.6% (95% CI 22.3; 39.5) were significantly exposed to the sale of sugar-sweetened drinks, 30 (Table 4) when analyzing the relationship between selling these foods through alternative sale outlets and adherence to school meals.  Table 3. Adherence to school meals, according to characteristics of school environment among public schools that offered school meals, Brazil, 2015. 95%CI: 95% confidence interval.

DIS CUSSION
This study's results showed that adherence to school meals is associated with the school's geographical characteristics and environment. Adherence showed a low value despite the high percentage of schools offering food to students. Schoolchildren in the North and Northeast regions, capitals, and urban areas showed lower school meal adherence. Regarding the characteristics of the internal environment, attending schools with a cafeteria and an alternative food sale outlet adversely interferes in adherence to school meals.
PNAE is a universal program that aims to provide healthy food to students in Brazilian public schools, and all students must regularly consume school meals. However, this study shows that adherence to school meals is low, corroborating the findings of Locatelli et al. 19 , who found low regular consumption of school meals among students assessed in PeNSE 2012 (22.8%). An integrative review that evaluated school meals programs in Brazil and the United States found a similar result, showing a low adherence and acceptance in both programs 28 .
The national literature shows that the factors associated with low adherence to school meals among adolescents are both at the individual level, such as gender, age, race, maternal education, having a paid job, and socioeconomic conditions 16,17,18,19,20,21 , and the school context 17,22 . The presence of a cafeteria 17,22 and poorer student perception of the physical structure of the cafeteria 21 were negatively associated with adherence to school meals. However, the characteristics of the school environment are still poorly explored at the national level 17,22 .
This study's results showed that schoolchildren from the Midwest and South regions who do not live in the capital and attend schools in the rural area showed greater adherence to school meals. However, there was a more generous supply of food in schools in the urban area and the South and Southeast regions, with no difference between capital and non-capital municipalities. Thus, it can be said that adherence to school meals is not influenced only by the food supply.
It is known that the external food environment, which are food sale physical spaces, including schools and informal vendors, influences the food choices of adolescents 5 . When evaluating the food environment of Brazilian public schools, Carmo et al. 10 did not identify differences in the supply of school meals between the Brazilian macro-regions. However, they identified that schools in the North Region had the most obesogenic food environment. A higher proportion of informal vendors was observed at or around the school gates in the North region compared to the Southeast, South, and Midwest regions, which may explain the higher adherence to school meals observed among adolescents in the Midwest and South, reinforcing the hypothesis that the school food environment interferes with adherence to school meals.
Locatelli et al. 19 also found that students from the Midwest Region who did not live in capitals had a higher prevalence of regular intake of school meals. Hoffmann 18 studied the consumption data for school meals from the National Household Sample Survey (PNAD) of 2004 and 2006 and found greater consumption, which is favorable to the affirmative answer to the question about the consumption of food offered by the school among adolescents in the North, Northeast and Midwest regions and residents of rural areas.
Adequate adherence (consumption 4 to 5 times a week) of school meals was also higher in rural schools than in urban schools in a study carried out with 492 adolescents enrolled in the state schools of Lapa (PR), carried out by Cesar et al. 16 . The authors attributed this result to the longer commuting time to the rural residents' school, thus making the time interval until the next meal longer, besides the eating habits of rural families being closer to the menus offered by the school compared to students in the urban area 16 . Rural households have greater availability and consumption of fresh or minimally processed food than urban households 29,30 . Therefore, the habits and food culture of adolescents in rural areas may be contributing to greater adherence to school meals.
The shorter distance and higher density of establishments selling unhealthy foods around schools are associated with poorly nutritious food choices among adolescents 31 . Thus, another possible explanation for the greater adherence to school meals among students in the rural area may be related to the greater adherence observed among schoolchildren without a cafeteria and point of sale, which can contribute to the lower availability of competing foods, which are not included in schools' menus.
Besides the geographic characteristics of the school, the results of this study indicate that adherence to school meals is also associated with the characteristics of the school environment, as students from schools with a cafeteria and an alternative food-selling outlet had less adherence to food. Similarly, Sturion et al. 17 evaluated 2,678 schoolchildren from the 1st to the 8th grade of elementary education in ten Brazilian municipalities, two from each geographic region, and found that commercial cafeterias in schools are inversely associated with daily adherence to the PNAE. Therefore, the availability and advertising of ultra-processed foods in the school environment influence the adolescents' food choices 5 and can be considered determining factors in the adherence to the food offered by the school, since it has been previously identified that adolescents who regularly buy food from the cafeteria are less likely to adhere to school meals 20 .
School menus and adolescent food consumption were not evaluated in this study. However, a study that used the same sample as PeNSE 2015 found that those who attended schools in the capitals were more likely to regularly consume ultra-processed snacks and soft drinks than those who attended schools in non-capitals, which is possibly related to the greater availability of alternative sale outlets or cafeterias inside or near schools 32 . Similarly, it is suggested that the lower adherence to school meals by students from the capitals in this study may be associated with food preferences and the school environment, which generally has a higher availability of competitive foods.
When evaluating the sale of unhealthy foods in the school environment, lower adherence to school meals was observed only among students exposed to the sale of soft drinks in cafeterias, although a higher prevalence of adolescents exposed to soft drinks and other markers was observed in places with alternative sale outlets. Regular consumption of soft drinks is inversely associated with adherence to school meals 10,22 , reinforcing the findings of this study regarding the negative influence of soft drink sales in the school environment on adherence to school meals.
Furthermore, the preference for foods with low nutritional value and high energy density is reasonably common among adolescents 33 , as such options are not included in school meals because the PNAE legislation requires the supply of fruits and vegetables, limits the supply of ultra-processed sweets and purchases, and prohibits the offering of sugarsweetened drinks 15 , which, associated with easy access to these foods in the school environment, can influence the level of adherence 16 . In a study conducted with adolescents from 23 public schools in Colombo (PR), Valentim et al. 21 found a high prevalence of competitive food consumption during their stay at school. Thus, the authors uncovered that the hypothesis of school meals not meeting students' preferences seems to have been confirmed.
According to Carmo et al. 10 , the school environment can be obesogenic, depending on the foods sold in cafeterias and their surroundings. On the other hand, positive effects on Brazilian students' eating habits who consume the meals offered by the school have already been evidenced.
In the USA, studies have shown that policies and regulations related to food sales in schools have resulted in improved eating habits among schoolchildren 7 . In Brazil, less than half of the states have a legal provision (ordinance, resolution, decree, or law) related to the sale of food in the school environment 10 . Also, many school cafeterias fail to comply with food marketing rules 28,34 . In this study, despite the high percentage of students benefiting from school meals in public schools, approximately half of the Brazilian states showed adherence below 30%. Therefore, the State must adopt measures to restrict or even prohibit the sale of unhealthy foods in and around the school environment throughout Brazil. Also, monitoring and inspection are essential to ensure compliance.
In this context, it is essential to highlight the importance of Food and Nutrition Education within the scope of the PNAE, which aims to encourage the voluntary adoption of healthy food practices and choices to promote learning, student good health, and individual quality of life 15 . Still, through food and nutrition education actions, it is possible to stimulate the consumption of school meals, thus favoring the achievement of one of the principles of the PNAE, universal service.
The acceptability of the menu and the consumption of other foods in the cafeterias and around the school were not evaluated in this study, which can interfere with adherence to school meals 28 . Moreover, it is worth mentioning that the questions regarding the sale of food in the school environment were answered by school principals, who, in turn, do not make up the target audience of these establishments. Thus, the possible unawareness of the directors regarding items sold may have interfered with this result. On the other hand, using a nationwide database with a high response rate is a strength of this study 23 .

CONCLUSION
Thus, we conclude that adherence to school meals is influenced by geographic characteristics and the school environment, emphasizing the negative association of a cafeteria and alternative outlet of sale with adherence to food offered by the school. Therefore, it is essential to adopt measures that prevent the sale of unhealthy foods in the school environment. It is also considered that, for the PNAE to achieve universal service, it is necessary to promote effective nutritional education actions involving the entire school pedagogical staff to foster the adoption of healthy habits and strengthen and improve the program.