Abstract

Introduction

The epidemiological and nutritional scenario in recent decades has proven dynamic, resulting from global changes in lifestyles ¹1. Schmidt MI, Duncan BB, Silva GA, Menezes AM, Monteiro CA, Barreto SM, et al. Chronic non-communicable diseases in Brazil: burden and current challenges. Lancet 2011; 377:1949-61.. Urbanization and industrialization have contributed to changes in eating patterns ²2. Popkin BM. Global nutrition dynamics: the world is shifting rapidly toward a diet linked with noncommunicable diseases. Am J Clin Nutr 2006; 84:289-98. and the emergence of sedentary behaviors ³3. Owen N, Sparling PB, Healy GN, Dunstan DW, Matthews CE. Sedentary behavior: emerging evidence for a new health risk. Mayo Clin Proc 2010; 85:1138-41.. With the food transition, the dietary profile of populations has been characterized by high energy density, while high-fiber and nutritionally balanced foods have been replaced by heavily-processed high-fat and high-sugar products ²2. Popkin BM. Global nutrition dynamics: the world is shifting rapidly toward a diet linked with noncommunicable diseases. Am J Clin Nutr 2006; 84:289-98.^,44. Martins APB, Levy RB, Claro RM, Moubarac JC, Monteiro CA. Participação crescente de produtos ultraprocessados na dieta brasileira (1987-2009). Rev Saúde Pública 2013; 47:656-65..

According to the NOVA classification proposed by Monteiro et al. ⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21:5-17., ultra-processed foods (UPF) differ from less processed foods in that they fail to maintain their basic identity, undergoing various processing stages and techniques and including substances used exclusively in industries. UPF are nutritionally unbalanced and heavily consumed in high-income countries, but their consumption is also growing rapidly in medium-income countries like Brazil ⁶6. Monteiro CA, Moubarac JC, Cannon G, Ng SW, Popkin B. Ultra processed products are becoming dominant in the global food system. Obes Rev 2013; 14 Suppl 2:21-8.. Examples of these products include cream-filled cookies, “packaged” salty snacks, sodas, and “instant” noodles, among others ⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21:5-17.. The low nutritional quality of these foods has a negative impact on individuals’ health, and the consumption of UPF has been related to altered lipid profile in children ⁷7. Rauber F, Campagnolo P, Hoffman D, Vitolo M. Consumption of ultra-processed food products and its effects on children's lipid profiles: a longitudinal study. Nutr Metab Cardiovasc Dis 2015; 25:116-22., metabolic syndrome in adolescents ⁸8. Tavares LF, Fonseca SC, Rosa MLG, Yokoo EM. Relationship between ultra-processed foods and metabolic syndrome in adolescents from a Brazilian Family Doctor Program. Public Health Nutr 2012; 15:82-7., and obesity in adolescents and adults ⁹9. Louzada MLC, Baraldi LG, Steele EM, Martins APB, Canella DS, Moubarac JC, et al. Consumption of ultra-processed foods and obesity in Brazilian adolescents and adults. Prev Med 2015; 81:9-15..

Meanwhile, among adolescents, the time spent at sedentary behaviors like watching TV and using videogames and computers has increased over time ¹⁰10. Moreno LA, Gottrand F, Huybrechts I, Ruiz JR, González-Gross M, DeHenauw S, et al. Nutrition and lifestyle in european adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study. Adv Nutr 2014; 5:615S-23S.. The habit of spending more time sitting is associated with several unfavorable health outcomes ¹⁰10. Moreno LA, Gottrand F, Huybrechts I, Ruiz JR, González-Gross M, DeHenauw S, et al. Nutrition and lifestyle in european adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study. Adv Nutr 2014; 5:615S-23S.^,1111. Costigan SA, Barnett L, Plotnikoff RC, Lubans DR. The health indicators associated with screen-based sedentary behavior among adolescent girls: a systematic review. J Adolesc Health 2013; 52:382-92.^,1212. Nelson MC, Gordon-Larsen P. Physical activity and sedentary behavior patterns are associated with selected adolescent health risk behaviors. Pediatrics 2006; 117:1281-90., including obesity ³3. Owen N, Sparling PB, Healy GN, Dunstan DW, Matthews CE. Sedentary behavior: emerging evidence for a new health risk. Mayo Clin Proc 2010; 85:1138-41., and can lead to greater consumption of UPF ¹³13. Vereecken CA, Todd J, Roberts C, Mulvihill C, Maes L. Television viewing behaviour and associations with food habits in different countries. Public Health Nutr 2006; 9:244-50.^,1414. Santaliestra-Pasías AM, Mouratidou T, Verbestel V, Huybrechts I, Gottrand F, Le Donne C, et al. Food consumption and screen-based sedentary behaviors in European adolescents: the HELENA study. Arch Pediatr Adolesc Med 2012; 166:1010-20. due to the ease in ingesting these products, since they are purchased in packaged form, ready to eat or heat ⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21:5-17.. Adolescence is an important phase for health promotion and the prevention of risk factors, since eating habits are acquired during this phase, as well as in childhood, and tend to persist throughout life ¹⁵15. World Health Organization. Diet, nutrition and the prevention of chronic diseases. Geneva: World Health Organization; 2003. (WHO Technical Report Series, 916)..

The literature on consumption of UPF using the NOVA classification ⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21:5-17. is still limited in Brazil, especially in children and adolescents ⁷7. Rauber F, Campagnolo P, Hoffman D, Vitolo M. Consumption of ultra-processed food products and its effects on children's lipid profiles: a longitudinal study. Nutr Metab Cardiovasc Dis 2015; 25:116-22.^,88. Tavares LF, Fonseca SC, Rosa MLG, Yokoo EM. Relationship between ultra-processed foods and metabolic syndrome in adolescents from a Brazilian Family Doctor Program. Public Health Nutr 2012; 15:82-7.^,99. Louzada MLC, Baraldi LG, Steele EM, Martins APB, Canella DS, Moubarac JC, et al. Consumption of ultra-processed foods and obesity in Brazilian adolescents and adults. Prev Med 2015; 81:9-15.^,1616. Levy RB, Castro IRR, Cardoso LO, Tavares LF, Sardinha LMV, Gomes FS, et al. Consumo e comportamento alimentar entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Ciênc Saúde Coletiva 2010;15 Suppl 2:3085-97.. At the international level, the existing data are related to trends in the sales of these products in 79 lower-middle, upper-middle, and upper-income countries ⁶6. Monteiro CA, Moubarac JC, Cannon G, Ng SW, Popkin B. Ultra processed products are becoming dominant in the global food system. Obes Rev 2013; 14 Suppl 2:21-8. and in Latin America ¹⁷17. Pan American Health Organization. Ultra-processed food and drink products in Latin America: Trends, impact on obesity, policy implications. Washington DC: Pan American Health Organization; 2015.. The relationship with sedentary behavior was studied previously in Brazil with data from the 2009 edition of the Brazilian National School Health Survey (PeNSE) ¹⁸18. Camelo LV, Rodrigues JFC, Giatti L, Barreto SM. Lazer sedentário e consumo de alimentos entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Cad Saúde Pública 2012; 28:2155-62.. However, the authors assessed regular consumption (≥ 5 days/week) of sodas, candy, cookies, and cold cuts, separately, one by one. The study’s results showed higher prevalence rates of regular consumption of these foods by individuals that reported more than two hours/day watching TV ¹⁸18. Camelo LV, Rodrigues JFC, Giatti L, Barreto SM. Lazer sedentário e consumo de alimentos entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Cad Saúde Pública 2012; 28:2155-62..

Given the above, the aim of the current study was to investigate the association between sedentary behavior and daily consumption of at least one group of UFP by adolescents enrolled in public and private schools in Brazil. The study can contribute to the literature on food consumption, using a classification that considers not only food’s nutrients, but the nature, extent, and degree of its processing. The study can also add to knowledge on the relationship between sedentary behavior and consumption of UFP, two important and harmful behaviors for adolescents’ health.

Methodology

This cross-sectional study used data from the 2015 edition of the PeNSE, with adolescents enrolled in the 9^th grade (formally the 8^th grade in the Brazilian school system) during the 2015 school year, with regular attendance at public and private schools in urban and rural areas all across Brazil. This was the third edition of the survey (the first two were in 2009 and 2012), conducted by the Brazilian Institute of Geography and Statistics (IBGE) in collaboration with the Brazilian Ministry of Health ¹⁹19. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde do Escolar - 2015. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2016..

The sample was sized to estimate the parameters for each of the 26 state capitals and the Federal District, which comprised the strata, consisting of the country’s five major geographic regions (North, Northeast, Southeast, South, and Central), in addition to non-state capital municipalities in each region. To represent the interior of Brazil, some municipalities outside the state capitals were grouped as a stratum for each of the states, totalizing 26 strata. For municipalities, state capitals, and the Federal District, the schools were the primary sampling units, classes were the secondary sampling units, and the students comprised the sample in each stratum ¹⁹19. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde do Escolar - 2015. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2016..

Just as in the geographic strata formed by the state capitals, in the municipalities the sample was random and equiprobable, selecting one class in schools with two 9^th grade classes and two classes in schools with three or more classes. All the students in the sampled classes were invited to answer the study questionnaire. Data were collected from April to September 2015, using smartphones on which a self-administered questionnaire was downloaded. Further details on the sampling process and study topics are available in the PeNSE 2015 publication ¹⁹19. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde do Escolar - 2015. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2016..

The outcome was daily consumption of at least one group of ultra-processed food, defined according to the NOVA classification ⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21:5-17.. The variable was operationalized with the following question: “In the last 7 days, on how many days did you eat...?” for each of the following foods/food groups: sweets or candy (candy, chocolate, chewing gum, bonbons, or lollipops); sodas and industrialized/ultra-processed salty foods like hamburgers, ham, baloney, salami, sausage, hot dogs, instant noodles, packaged salty snacks, and crackers. Daily consumption of at least one group of UPF was defined as an affirmative answer to the consumption of at least one of the groups on all seven days of the study week.

The principal exposure was sedentary behavior, in hours per day, measured with the following question: “On an ordinary week day, how long do you spend sitting, watching TV, using the computer, playing videogames, talking with friends, or doing other activities? (not including Saturdays, Sundays, holidays, and time sitting at school)”. The answers were: “up to 1 hour a day; more than 1 hour and up to 2 hours a day; more than 2, up to 3; more than 3, up to 4; more than 4, up to 5; more than 5, up to 6; more than 6, up to 7; more than 7, up to 8; more than 8 hours a day”.

The following variables were included in the analyses as possible confounders: gender (male, female), age (≤ 13, 14, 15, and ≥ 16 years), self-reported skin color/race (white, black, Asian-descendent/indigenous, brown), maternal schooling (none, incomplete primary, incomplete secondary, incomplete university, complete university), household assets (in quintiles), geographic region (North, Northeast, Southeast, South, Central-West), and school’s administrative jurisdiction (public, private). The household assets index consisted of hardline telephone, computer (desktop, notebook, laptop, etc.), car and/or motorcycle, number of bathrooms with shower/bath, and home internet access. Students were also asked whether they had their own cellphone and if the household had a housekeeper (at least three days a week). The household assets index was built using the first component obtained, based on a principal components analysis ²⁰20. Barros AJ, Victora CG. Indicador econômico para o Brasil baseado no Censo Demográfico de 2000. Rev Saúde Pública 2005; 39:523-9..

Initially, the sample was described according to demographic and socioeconomic characteristics, as well as prevalence rates and respective 95% confidence intervals (95%CI) ¹⁹19. Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional de Saúde do Escolar - 2015. Rio de Janeiro: Instituto Brasileiro de Geografia e Estatística; 2016. for the outcome weighted for these variables. Adjusted prevalence rates and 95%CI for daily consumption of each group of UPF were analyzed according to daily time of sedentary behavior, dichotomized as ≤ 2 hours versus > 2 hours. This cutoff point was based on the American Academy of Pediatrics ²¹21. Bar-On ME, Broughton DD, Buttross S, Corrigan S, Gedissman A, González De Rivas MR, et al. Children, adolescents, and television. Pediatrics 2001; 107:423-6., which recommends two hours as the maximum screen time for children over two years of age and adolescents. Finally, we performed an adjusted analysis of the number of hours of sedentary behavior per day in ordinal form (≤ 1 hour and > 8 hours/day) and the outcome by means of Poisson regression ²²22. Barros AJ, Hirakata VN. Alternatives for logistic regression in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio. BMC Med Res Methodol 2003; 3:21., producing prevalence ratios (PR) and 95%CI. All the adjustment variables were included, regardless of p-value in the crude analysis. All the analyses were performed with the svy command in order to account for the sample design effect, using Stata, version 12.1 (StataCorp LP, College Station, USA).

PeNSE 2015 was approved by the National Commission on Research Ethics (CONEP), of the National Health Council, which regulates and rules on health studies involving human subjects (CONEP case review n. 1.006.467, March 30, 2015).

Results

The sample totaled 102,072 students, 101,755 of whom furnished information on their consumption of the target foods. The majority of the subjects were female (51.3%), 50.9% were 14 years old, and 43% reported brown skin color. As for maternal schooling, 30.9% said their mothers had incomplete higher education. The Southeast region of Brazil provided the largest proportion of students in the sample (43.3%). The vast majority were enrolled in public schools (85.5%) (Table 1). Daily consumption of at least one group of UPF was reported by 39.7% (95%CI: 39.2-40.3) of the subjects. As for sedentary behavior, 68.1% (95%CI: 67.7-68.7) of the schoolchildren reported spending more than two hours a day at sitting activities.

The highest prevalence rates of daily consumption of at least one UPF were in girls, among adolescents living in the Southeast and Central regions and enrolled in private schools. Prevalence rates of daily consumption of UPF were higher in the quintiles with the highest household assets indices and maternal schooling, reported by the adolescents (p-value < 0.001). Age and skin color were not associated with daily consumption of UPF (Table 1).

Figure 1 shows the adjusted prevalence rates and 95%CI for daily consumption of each group of UPF separately, according to time spent in sedentary behavior. Adolescents with more than two hours a day of sedentary behavior showed higher prevalence rates of daily consumption of UPF compared to those with two hours or less, for the three foods analyzed separately. Daily consumption of sweets was the most prevalent, exceeding 28% among students with greater sedentary behavior (Figure 1).

Besides the differences for each group of UPF separately, the consumption of at least one group of UPF was directly associated with time spent at sedentary behavior. For the dichotomous exposure, 42.8% of adolescents with more than two hours a day of sedentary behavior consumed at least one UPF daily, versus 29.8% for sedentary behavior less than or equal to two hours (Figure 1). Considering the ordinal form of exposure, after adjusting for the other variables, more hours of sedentary behavior were associated with higher prevalence rates of daily consumption of UPF (p-value for linear trend < 0.001), with a dose-response effect in the associations (Figure 2).

Discussion

The study showed high prevalence rates for daily consumption of at least one group of UFP and more than two hours a day of sedentary behavior; four out of ten and seven out of ten Brazilian adolescents, respectively, displayed such behaviors. Even after adjustment, the study showed a positive association between time spent at sedentary behavior and daily consumption of at least one group of UPF, with a dose-response effect; longer sedentary behavior was associated with higher prevalence of daily consumption of UPF.

Levy et al. ¹⁶16. Levy RB, Castro IRR, Cardoso LO, Tavares LF, Sardinha LMV, Gomes FS, et al. Consumo e comportamento alimentar entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Ciênc Saúde Coletiva 2010;15 Suppl 2:3085-97. investigated regular consumption (≥ 5 days/week) of four groups of UFP by adolescents in the 2009 edition of the PeNSE survey, with high proportions of adolescents that consumed sweets, sodas, cookies, and cold cuts (50.9%, 37.2%, 33.6%, and 18%, respectively). Data from the second edition of PeNSE (2012) showed prevalence rates of regular consumption (≥ 5 days/week) of sweets, sodas, cookies, fried salty snacks, and packaged salty snacks among adolescents: 41.3%, 33.3%, 32.5%, 15.8%, and 13%, respectively ²³23. Azeredo CM, Rezende LFM, Canella DS, Claro RM, Castro IRR, Carmo Luiz O, et al. Dietary intake of Brazilian adolescents. Public Health Nutr 2015; 18:1215-24.. The current study assessed daily consumption of at least one UPF, and although the servings (in grams or mL) of these foods consumed are not known, it is troublesome that four out of ten Brazilian adolescents reported consuming these foods on a daily basis.

In relation to sedentary behavior, a study of adolescents in Santa Catarina State, Brazil, found that more than 70% watched TV or used the computer or played videogames for more than two hours a day ²⁴24. Silva KS, Nahas MV, Hoefelmann LP, Lopes AS, Oliveira ES. Associações entre atividade física, índice de massa corporal e comportamentos sedentários em adolescentes. Rev Bras Epidemiol 2008; 11:159-68., a similar figure to our finding. Gordon-Larsen et al. ²⁵25. Gordon-Larsen P, Nelson MC, Popkin BM. Longitudinal physical activity and sedentary behavior trends: adolescence to adulthood. Am J Prev Med 2004; 27:277-83., evaluating longitudinal trends in sedentary behavior, found that one-fourth of adolescents in the study reported more than two hours a day of sedentary behavior and that the habit persisted into adulthood. Camelo et al. ¹⁸18. Camelo LV, Rodrigues JFC, Giatti L, Barreto SM. Lazer sedentário e consumo de alimentos entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Cad Saúde Pública 2012; 28:2155-62. showed that 65% of the students in PeNSE 2009 reported spending more than two hours a day watching TV, and Malta et al. ²⁶26. Malta DC, Sardinha LMV, Mendes I, Barreto SM, Giatti L, Castro IRR, et al. Prevalência de fatores de risco e proteção de doenças crônicas não transmissíveis em adolescentes: resultados da Pesquisa Nacional de Saúde do Escolar (PeNSE), Brasil, 2009. Ciênc Saúde Coletiva 2010; 15:3009-19. found that approximately 80% of this same population reported this habit for at least two hours a day. Neither study reported data on the use of computers and videogames. Although the latter devices were not included in the study, the hours were greater than in our study. Such differences may be due to the fact that PeNSE 2009 only included state capitals and the Federal District, while PeNSE 2015 also included municipalities from the interior of the states.

The analysis of the association between sedentary behavior and consumption of UFP, adjusted for confounding, showed that the longer the time spent at sedentary behavior, the higher the prevalence of daily consumption of at least one UPF. These findings are consistent with the literature. A systematic review found that sedentary behavior in children and adolescents was directly associated with the consumption of high-energy snacks and beverages, fast food, and total energy intake ²⁷27. Pearson N, Biddle SJ. Sedentary behavior and dietary intake in children, adolescents, and adults: a systematic review. Am J Prev Med 2011; 41:178-88.. Camelo et al. ¹⁸18. Camelo LV, Rodrigues JFC, Giatti L, Barreto SM. Lazer sedentário e consumo de alimentos entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Cad Saúde Pública 2012; 28:2155-62. found that students in PeNSE 2009 who reported regular consumption (≥ 5 days/week) of sweets, sodas, cookies, and cold cuts showed higher odds of more than two hours of TV time a day. A study of schoolchildren in New Zealand found that kids who watch more than two hours of TV a day had higher odds of consuming foods commonly advertised on television (sodas and artificial juices, sweets, snacks, and fast food) ²⁸28. Utter J, Scragg R, Schaaf D. Associations between television viewing and consumption of commonly advertised foods among New Zealand children and young adolescents. Public Health Nutr 2006; 9:606-12..

There are two possible explanations for this association. The first is the greater inherent practicality of UFP, allowing consumption anywhere without the need for preparation, cooking, or dishes or tableware, favoring the consumption of this type of food while the adolescent watches TV or uses the computer or plays videogames ⁵5. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018; 21:5-17.. Besides, kids who spend more time at sedentary behavior are probably more exposed to advertising of UFP. Advertising campaigns exploit kids’ vulnerability in order to encourage them to consume unhealthy products, heavily influencing their eating preferences ²⁹29. Mallarino C, Gómez LF, González-Zapata L, Cadena Y, Parra DC. Advertising of ultra-processed foods and beverages: children as a vulnerable population. Rev Saúde Pública 2013; 47:1006-10.. Pearson & Biddle ²⁷27. Pearson N, Biddle SJ. Sedentary behavior and dietary intake in children, adolescents, and adults: a systematic review. Am J Prev Med 2011; 41:178-88. reported in a systematic review that in children and adolescents, sedentary behavior in general was inversely associated with the consumption of fruits and vegetables and directly associated with the consumption of high energy-dense snacks, fast food, and high energy-dense beverages. The lack of specific regulation of advertising for ready-to-eat or UFP poses a major obstacle to healthy eating ³⁰30. Victora CG, Barreto ML, Carmo Leal M, Monteiro CA, Schmidt MI, Paim J, et al. Health conditions and health-policy innovations in Brazil: the way forward. Lancet 2011; 377:2042-53.^,3131. Henriques P, Dias PC, Burlandy L. A regulamentação da propaganda de alimentos no Brasil: convergências e conflitos de interesses. Cad Saúde Pública 2014; 30:1219-28..

Some study limitations should be addressed, such as the possibility of reverse causality in studies that collect data on outcome and exposure at the same time, where it is not possible to determine whether the sedentary behavior causes greater consumption of UPF or if it represents an effect of the latter. Despite the possibility of this bias, the direction of the target association gains greater relevance if one considers that lifestyle-related behaviors like diet, physical activity, and sedentary behavior generally tend to converge in harmful paths for health ³²32. Leech RM, McNaughton SA, Timperio A. The clustering of diet, physical activity and sedentary behavior in children and adolescents: a review. Int J Behav Nutr Phys Act 2014; 11:4.. Studies have shown that increased prevalence rates of excess weight are seen in children and adolescents that display clusters of behaviors, including the combination of less physical activity and more sedentary behavior ³³33. Dumuid D, Olds T, Lewis L, Martin-Fernández J, Barreira T, Broyles S, et al. The adiposity of children is associated with their lifestyle behaviours: a cluster analysis of school-aged children from 12 nations. Pediatr Obes 2018; 13:111-9., plus more screen time and less nighttime sleep, less average dinner time duration, and fewer outdoor games ³⁴34. Watanabe E, Lee JS, Mori K, Kawakubo K. Clustering patterns of obesity-related multiple lifestyle behaviours and their associations with overweight and family environments: a cross-sectional study in Japanese preschool children. BMJ Open 2016; 6:e012773.. Another possible limitation to the study is the lack of information on cellphone use in the 2015 edition of the PeNSE survey. Despite the possible underestimation of prevalence of sedentary behavior, the literature shows that the direction of the association between cellphone use and consumption of unhealthy foods is the same as in the current study ³⁵35. Delfino LD, Santos Silva DA, Tebar WR, Zanuto EF, Codogno JS, Fernandes RA, et al. Screen time by different devices in adolescents: association with physical inactivity domains and eating habits. J Sports Med Phys Fitness 2017. [Epub ahead of print].. Thus, this association may not have been greatly influenced by the lack of information on cellphone use.

Although the data on eating that is available in the PeNSE 2015 survey includes a large share of UPF, information is obviously lacking on other foods belonging to this group, which were not asked about in the questionnaire. Therefore, it was not possible to include the adolescents’ eating environment among the adjustment variables. Considering the high prevalence of consumption of cookies in the PeNSE 2009 survey (33.6%) ¹⁶16. Levy RB, Castro IRR, Cardoso LO, Tavares LF, Sardinha LMV, Gomes FS, et al. Consumo e comportamento alimentar entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Ciênc Saúde Coletiva 2010;15 Suppl 2:3085-97. and that cookies were not included in the 2015 edition, consumption of UFP may be underestimated in the current study. The association may also have been underestimated considering that prevalence in the exposed individuals (longer time spent at sedentary behavior) tends to be underestimated. The consumption of high-sugar beverages besides sodas was also not included in the 2015 edition of PeNSE. Tavares et al. ³⁶36. Tavares LF, Castro IRR, Levy RB, Cardoso LO, Passos MD, Brito FSB. Validade relativa de indicadores de práticas alimentares da Pesquisa Nacional de Saúde do Escolar entre adolescentes do Rio de Janeiro. Cad Saúde Pública 2014; 30:1029-41. found regular consumption (≥ 5 days/week) of high-sugar beverages in 55.2% of adolescents interviewed in Rio de Janeiro, which may contribute to the underestimation of both the prevalence and the association. In addition, the questionnaires were completed by the adolescents themselves, with the possibility of information bias ³⁶36. Tavares LF, Castro IRR, Levy RB, Cardoso LO, Passos MD, Brito FSB. Validade relativa de indicadores de práticas alimentares da Pesquisa Nacional de Saúde do Escolar entre adolescentes do Rio de Janeiro. Cad Saúde Pública 2014; 30:1029-41.^,3737. Tavares LF, Castro IRR, Cardoso LO, Levy RB, Claro RM, Oliveira AF. Validade de indicadores de atividade física e comportamento sedentário da Pesquisa Nacional de Saúde do Escolar entre adolescentes do Rio de Janeiro, Brasil. Cad Saúde Pública 2014; 30:1861-74.. However, the questions used in this study are easy to grasp, so the risk of information bias is small. The lack of information on urban/rural residence allows the existence of bias in the associations, considering that ready-to-eat meals, industrialized mixtures, and sodas are less available in rural areas when compared to urban ³⁸38. Levy RB, Claro RM, Mondini L, Sichieri R, Monteiro CA. Distribuição regional e socioeconômica da disponibilidade domiciliar de alimentos no Brasil em 2008-2009. Rev Saúde Pública 2012; 46:6-15.. Thus, adolescents in rural areas may report lower consumption simply due to lower household availability. Finally, the sampling loss in the adjusted analysis (25.4% of all the study subjects), resulting basically from the maternal schooling variable, could mean overestimation of the prevalence of consumption of UFP, considering that those who did not furnish data on maternal schooling are those in the lowest household assets quintiles and consequently those with the lowest consumption of these foods. This association may be overestimated, since the respondents are found in the highest quintiles of household assets, and the prevalence of both the exposure and the outcome is higher among these students (data not shown).

PeNSE 2015 is a school-based survey with a nationwide scope, an advantage for studies that use its database. In addition, despite the lack of information on daily servings and the calorie contribution of the target foods, the analyses allowed assessing the consumption of a set of UPF, and not only of single items like sodas or fast food. Compared to studies using data from the first two editions of PeNSE (2009 and 2012) ³3. Owen N, Sparling PB, Healy GN, Dunstan DW, Matthews CE. Sedentary behavior: emerging evidence for a new health risk. Mayo Clin Proc 2010; 85:1138-41.^,1818. Camelo LV, Rodrigues JFC, Giatti L, Barreto SM. Lazer sedentário e consumo de alimentos entre adolescentes brasileiros: Pesquisa Nacional de Saúde do Escolar (PeNSE), 2009. Cad Saúde Pública 2012; 28:2155-62., the current study adds information, since it expands the exposure variable and shows an alternative approach to the outcome variable (the combination of UFP) in the attempt to depict adolescents’ eating habits rather than the consumption of single foods. The 2015 edition also has a broader scope than PeNSE 2009, since it includes data on students from municipalities in the interior of the states, in addition to data on students from the state capitals and the Federal District.

Consumption of UFP has increased in Brazil ⁴4. Martins APB, Levy RB, Claro RM, Moubarac JC, Monteiro CA. Participação crescente de produtos ultraprocessados na dieta brasileira (1987-2009). Rev Saúde Pública 2013; 47:656-65., and prevalence among adolescents was high in the current study. Efforts are thus needed to reduce the consumption of these foods. There is a need for widespread awareness-raising on diet and the resulting health/disease process, focusing on food choices and encouragement for fresh or minimally processed foods, based on disclosure of information.

Awareness-raising of parents and guardians on food choices and their consequences for health is essential for decreasing the consumption of UFP. The school is also a prime setting for nutritional education, not only as a sporadic measure, but incorporated into the school curriculum as a whole. Since schools set examples for students, the regulation of sale and advertising of foods in school canteens and the supply of healthy foods are necessary throughout the school system. Finally, population-wide policies are necessary, including regulation of advertising for UPF in the media in general and fiscal policies aimed at increasing access to healthier foods, which should enjoy lower tax rates. Likewise, higher taxation on unhealthy food products can help decrease the consumption of ultra-processed products.

A decrease in the prevalence of sedentary behavior can contribute positively to various health outcomes, since it is associated with several factors, including consumption of UPF. It is thus important to reduce prolonged sitting time and to increase the level of regular physical activity ³3. Owen N, Sparling PB, Healy GN, Dunstan DW, Matthews CE. Sedentary behavior: emerging evidence for a new health risk. Mayo Clin Proc 2010; 85:1138-41.. Longer time spent at sedentary behavior (not including time sitting at school) can occur in the family setting, and the American Academy of Pediatrics ²¹21. Bar-On ME, Broughton DD, Buttross S, Corrigan S, Gedissman A, González De Rivas MR, et al. Children, adolescents, and television. Pediatrics 2001; 107:423-6. recommends that parents limit their children’s screen time to no more than two hours a day, encouraging more physical activity by adolescents. This kind of information should also be widely publicized in order for parents to be able to follow such guidance. Opportunities for physical activities offered by schools outside of classroom hours can also be a good strategy to reduce time spent in sedentary behavior. Broader approaches like improving public spaces for physical exercise and policies to increase users’ perception of safety, especially in underprivileged neighborhoods, can encourage outdoor activities and active commuting, thus reducing the time spent in sedentary activities ³⁹39. Van Dyck D, Cardon G, De Bourdeaudhuij I. Which psychological, social and physical environmental characteristics predict changes in physical activity and sedentary behaviors during early retirement? A longitudinal study. PeerJ 2017; 5:e3242..

Conclusions

This study evidenced the association between two behaviors that are harmful to adolescents’ health. Strategies to reduce the prevalence of both factors are important, like regulation of the supply of UFP in schools and advertising for such foods, policies to improve the built (and perceived) environment for physical activity, and health promotion measures engaging parents and teachers, targeting to adolescents’ awareness-raising on healthy eating, sedentary behaviors, and the health-disease process. Such strategies are essential for avoiding unhealthy lifestyles that last into adulthood and thus further foment the growing prevalence of chronic non-communicable diseases.

References

Publication Dates

History