It is well established that countries’ wealth and welfare are associated with better health and nutrition outcomes among children and adults(Reference Marmot1). However, few studies have attempted to understand this association among adolescents(Reference Viner, Ozer and Denny2,Reference Beal, Morris and Tumilowicz3) , although like children, adolescents are among the most vulnerable to the effects of poverty and social and health inequalities. These may have an impact on adolescent’s physical and psychosocial development, as well as influence their choices and health behaviours, with consequences that persist in adult life(Reference Beal, Morris and Tumilowicz3,Reference Currie, Gabhainn and Godeau4) . Thus, it is important to expand studies to this stage of life, having adolescence as a window of opportunity for the promotion of healthy behaviours and long-term impact on health and nutrition outcomes(Reference Beal, Morris and Tumilowicz3,Reference Currie, Gabhainn and Godeau4) .
Adolescent health and nutrition are determined by multiple factors including proximal factors such as individual behaviours and friends and family influence, and distal factors such as education, national wealth and income inequality(Reference Viner, Ozer and Denny2). Despite the gap of studies examining adolescent health and distal factors, it is known that, usually, socio-economic disadvantages can limit food availability and access to health care and undermine people’s participation in actions that promote healthy dietary habits and the consumption of healthy foods, such as fruits and vegetables (FV)(Reference Elgar, Pförtner and White5,Reference Inchley, Currie and Young6) .
In general, greater country economic development is related to greater food availability. However, the impact of food availability on diet quality varies across countries. In the most developed countries, rising incomes are often associated with increased food availability, to healthier and more diverse diets and better health care(7). On the contrary, in developing countries, rising incomes have been associated with increased consumption of ultra-processed food and animal products, contributing to unhealthy and less diverse diets(Reference Elgar, Pförtner and White5–Reference Ochoa-Avilés, Verstraeten and Lachat9). Also, in these countries, increased national income tends to be followed by social and health inequalities, resulting in different effects in the population, depending on variables such as education. For instance, those with higher levels of education are more likely to pay for a diversified diet, while those in worst socio-economic conditions and lower levels of education have limited food choices and are more likely to pay for ultra-processed food(Reference Kearney10).
The Human Development Index (HDI) and the Gross National Income per capita (GNIpc) are among the main macroeconomic indicators used to estimate countries’ welfare and wealth, and they are potentially useful for international comparative analyses of countries’ association with national food consumption profiles. However, studies on this subject are scarce, mostly using food balance sheets for the general population instead of providing more reliable information on food consumption patterns(7,Reference Gerbens-Leenes, Nonhebel and Krol11–Reference Sampaio and Cardoso19) . Another important gap is that none of the studies specifically evaluated these parameters among adolescents.
Evidence indicates that countries with higher Gross Domestic Product per capita have greater availability of both healthy food consumption markers, such as FV(Reference Siegel, Ali and Srinivasiah13–Reference Asfaw15), and unhealthy food consumption markers, such as sugar(Reference Siervo, Montagnese and Mathers14) and typically Western foods, characterised by high energy density foods, large amounts of meat and animal fat and few whole grains(Reference Oggioni, Cena and Wells17,Reference Oggioni, Lara and Wells18) . A global study(Reference Muhammad, D’Souza and Meade20) that indicated higher fruit consumption in countries with higher Gross Domestic Product per capita also found a positive association between income and sweetened beverage consumption for Sub-Saharan Africa, suggesting variations in the association between macroeconomic indicators and food consumption by region. The same study also indicated differences in this association by sex and age when investigating adults and elderly.
Considering the complexity of adolescent dietary patterns, it is important to understand the association between macroeconomic indicators and food consumption in this age group to develop specific policies for the promotion of healthier habits among adolescents. Therefore, this study aimed to describe the consumption of healthy (FV) and unhealthy (carbonated soft drinks (CSD)) food markers among students from seventy-four countries, and its association with macroeconomic indicators.
Methods
Study design and sampling
This is an ecological study, using data from the Global School-based Student Health Survey (GSHS, 2003–2014), a collaborative surveillance project coordinated by the WHO with support from the Centers for Disease Control and Prevention. The GSHS is a nationally representative survey that has been largely applied in low–middle-income countries(Reference Beal, Morris and Tumilowicz3,21) . This study included seventy-four countries in the following regions: Africa (AFR: fourteen countries), Central and South America (AMR: twenty-three countries), Southeast Asia (SEAR: six countries), Europe (EUR: one country), Eastern Mediterranean (EMR: sixteen countries) and the Western Pacific (WPR: fourteen countries).
The GSHS focuses on students aged 13–17 years old(22,23) including different school grades according to the educational structure of each country(Reference Pierobon, Barak and Hazrati24–26). The survey sampling plan was similar across countries, defined by a two-stage cluster design: first, the schools were selected and then the classes. All the students in the selected classes were invited to respond to the questionnaire(Reference Pierobon, Barak and Hazrati24–26). The GSHS used a printed, self-administered questionnaire that was distributed during the classes. In the different countries investigated, specific questionnaires were used according to the local demands. The Centers for Disease Control and Prevention was responsible for digitising and processing the data(22,23) .
Brazil was not included in the GSHS, and data from a national survey using comparable indicators, the National School Health Survey (Pesquisa Nacional de Saúde do Escolar – PeNSE 2015 – Sample 2), were used(27). Questions about food groups were included in the same format adopted by the GSHS, precisely to enable comparison between the countries covered in this survey. PeNSE evaluated students enrolled in the final years of elementary and high school in Brazil following a three-stage sample design. Based on stratification by country region, groups of neighbouring municipalities were selected, followed by schools, and then classes. All students from these classes were invited to participate in the research. Data collection was conducted during school hours using a self-administered questionnaire applied through smartphones(27).
In the GSHS, the sample size varied between countries to ensure sufficient statistical power to estimate prevalence with accuracy equal to or greater than ± 5·0 % in each country. In PeNSE, the sample size was calculated to obtain an approximate error of 0·03 and a 95 % confidence level.
Investigated variables
The dependent variables analysed were the percentage of adolescents in each country who consumed CSD and FV daily. These food groups were chosen among all food consumption data collected by GSHS because they are part of the core questionnaire standardised for all countries, they are available in a considerable number of countries and they are routinely collected by other adolescent health surveillance systems, allowing for International comparison. Online Supplementary Fig. S1 shows the countries with information on CSD and FV consumption. The most recent data from each country were evaluated, considering all participants who were investigated (≥ 11 to ≤ 19 years).
The frequency of food consumption was assessed through common questions to both surveys, with reference to the last 30 days (answer options: I did not drink carbonated soft drink/eat fruit/eat vegetables during the past 30 days; Less than one time/day; 1 time/day; 2 times/day; 3 times/day; 4 times/day; 5 or more times/day)(21,27) . In view of the current recommendations for the consumption of ≥ 400 g/d of FV(7), and that daily consumption of CSD may be considered a marker of excessive consumption, the response options were recategorised into daily (≥ 1 times/d) and non-daily consumption.
The macroeconomic indicators evaluated included the HDI (2000–2015), a summarised measure of the fundamental dimensions of human development (health, education and life standard) available at the United Nations Development Programme(28), and the GNIpc (Atlas Method; 2003–2015), a national wealth indicator used to divide countries into income groups available from the World Development Indicators, World Bank(29). The HDI and GNIpc data used in this study were those in the closest years from the food consumption data (online Supplementary Fig. S1).
The independent variables in the study were the world regions (AFR, AMR, SEAR, EUR, EMR and WPR), continuous and categorised HDI (low: < 0·55; medium: 0·55 to < 0·7; high: 0·7 to < 0·8; very high human development: ≥ 0·8)(28) and continuous and categorised GNIpc (low income: ≤ US$1025·00; lower–middle-income: US$1026·00 to US$4035·00; upper–middle-income: US$4036·00 to US$12 475·00; high income: ≥ US$12 476·00 – according to World Bank income groups)(29).
Data analysis
Statistical tests were performed using SPSS software 17.0 for Windows (SPSS Inc.) and Stata (release 15; StataCorp LP). First, the countries databases were accessed individually to obtain their respective prevalence of CSD and FV daily consumption. Considering the representativeness of national data and its generalisation, the SPSS ‘Complex sample’ module was used, selecting the strata, clusters and sample weight variables specific to each country when carrying out the analysis. Then, information about the prevalence of food consumption was transferred to a new database, which aggregated this information and data on macroeconomic indicators for the set of countries investigated.
Descriptive analyses were conducted showing the prevalence, median and interquartile range data for food consumption by country. As the numerical variables did not have a normal distribution (Kolmogorov–Smirnov test), nonparametric analyses were adopted. The associations between the percentage of daily consumption and the world regions and human development and income groups were analysed using the Kruskal–Wallis test, followed by the Mann Whitney test adjusted by Bonferroni correction(Reference Field30).
Scatter plots were constructed for each indicator as a continuous variable (HDI and GNIpc (logarithmic form)) and for the prevalence of daily consumption of each food marker, together with a correlation test. Four countries (Brunei Darussalam, Kuwait, Qatar and United Arab Emirates) were considered outliers and excluded from the GNIpc analysis due to their high values in comparison with other countries.
A multilevel model was tested between the variables with significant correlation to consider the effects of region in the association. Random Intercept Models were used, considering country as the level 1 and region as the level 2. A likelihood ratio test was used to compare the multilevel model with a single-level model. In addition, variance partition coefficients were calculated to show the proportion of total variance in the outcome due to differences occurring at each level. The models were controlled by sex (percentage of female);, year of data collection, Consumer Price Index for food indices and the Per capita Food Supply for human consumption (kcal/capita/d). Stepwise multilevel analyses were conducted, and none of the control variables was statistically significant.
Ethical standards
This study was developed from secondary data. Research used as a data source was conducted according to the guidelines established in the Declaration of Helsinki, and all procedures involving research study participants were approved by the WHO, Centers for Disease Control and Prevention (specific approval number for each country) and the National Research Ethics Committee of the Brazilian Ministry of Health (nº 1.006.467). Written informed consent was obtained from all subjects/patients.
Results
In the seventy-four countries, 257 770 students were evaluated, ranging from 578 in Nauru (WPR) to 28 368 in Argentina (AMR), with 70·3 % of countries having a sample size of at least 2000 students (median sample size = 2375·5). In the investigated countries, 50·2 % of the adolescents were male and 49·8 % were female (online Supplementary Table S1). The AMR region contained the largest proportion of countries surveyed (31·1 %, twenty-three countries). Over 70·0 % of the countries had medium-to-high HDI and half had low or lower–middle income (Table 1).
General characteristics and socio-economic indicators in the seventy-four evaluated countries
(Number and percentages)
IQR, interquartile range.
* Low human development: < 0·55; medium: 0·55 to < 0·7; high: 0.7 to < 0·8; very high: ≥ 0·8.
† World Bank Income groups according to GNIpc: low income: ≤ US$1025·00; lower–middle-income: US$1026·00 to US$4035·00; upper–middle-income: US$4036·00 to US$12 475·00; high income: ≥ US$12 476·00.
The median prevalence of daily CSD consumption was 54·1 % (range, 41·6–65·5 %) (Table 2). The lowest frequency was observed in Kiribati (22·2 %; WPR) and the highest in Suriname (80·4 %; AMR). Among the fifty countries with available CSD consumption data, thirty (60 %) had daily prevalence rates over 50·0 % (online Supplementary Table S2). Higher values of CSD consumption were identified in the AMR region compared with other regions (65·6 % in AMR v. 43·8 % in AFR, 49·9 % in EMR and 42·0 % in WPR; P < 0·001), in countries with high HDI compared with low HDI (59·9 % v. 39·5 %; P = 0·006) and in high-income countries compared with lower–middle income countries (67·2 % v. 46·4 %; P = 0·010) (Table 2).
Prevalence of daily consumption of carbonated soft drinks, fruits and vegetables and macroeconomic indicators in the countries assessed, 2003–2015
(Numbers; median and interquartile range)
IQR, interquartile range; HDI, Human Development Index; GNIpc, Gross National Income per capita.
* Europe was not included because it presented data only from North Macedonia. For carbonated soft drinks, Southeast Asia was not included because it had only data from Maldives.
† Kruskal–Wallis test, with Bonferroni correction.
‡ Categories that differed significantly from each other.
§ Difference in relation to Central and South America.
|| Low human development: < 0·55; medium: 0·55 to < 0·7; high: 0·7 to < 0·8; very high: ≥ 0·8.
¶ Income groups according to GNIpc: low income: ≤ US$1025·00; lower–middle-income: US$1026·00 to US$4035·00; upper–middle-income: US$4036·00 to US$12 475·00; high-income: ≥US$12 476·00.
** For carbonated soft drinks, the low-income group was not included (only two countries with available data). Four countries (Brunei Darussalam, Kuwait, Qatar and United Arab Emirates) were excluded from this analysis due to extreme GNIpc values.
The median daily fruit consumption was 67·9 % (range, 58·9–73·3 %) (Table 2). The lowest prevalence was identified in Libya (35·2 %, EMR) and the highest in the North Macedonia (83·7 %, EUR) (online Supplementary Table S2). The median daily vegetable consumption was 74·6 % (range, 64·6–80·6 %) (Table 2). The lowest value was in the Maldives (36·6 %, SEAR) and the highest value was in Algeria (91·8 %, AFR) (online Supplementary Table S2). There were no significant differences between the macroeconomic indicators and daily consumption of FV (Table 2).
When examining the association between the continuous variables, CSD consumption was positively associated with HDI (correlation = 0·446, P = 0·001, Fig. 1(a)), and with GNIpc (correlation = 0·491, P < 0·001, Fig. 2(a)). On the other hand, no significant correlations were found between macroeconomic indicators and the consumption of fruits or vegetables (Figs. 1(b) and (c), 2(b) and (c)).
Prevalence of daily carbonated soft drink, fruits and vegetables consumption among adolescents according to the Human Development Index in the analysed countries (2003–2015). (a) Carbonated soft drink consumption: correlation: 0·446; P = 0·001. (b) Fruits consumption: correlation: −0·004; P = 0·970. (c) Vegetables consumption: correlation: −0·064; P = 0·592. HDI, Human Development Index.
Prevalence of daily carbonated soft drink, fruits and vegetables consumption among adolescents according to Gross National Income per capita in the analysed countries (2003–2015). (a) Carbonated soft drink consumption: correlation: 0·491; P < 0·001. (b) Fruits consumption: correlation: −0·067; P = 0·580. (c) Vegetables consumption: correlation: −0·197; P = 0·101. GNIpc, Gross National Income per capita presented in logarithmic form.
A multilevel null model was estimated to check the variation of CSD consumption at the country and region levels. A likelihood ratio test was used to compare null models with and without a second level (region), showing that the two-level model offered a significant better fit to the data (likelihood ratio = 20·55). The variance partition coefficient showed that 39 % of the variance in the CSD consumption could be attributed to the differences between regions. In both models, HDI and GNIpc were positively associated with CSD consumption (Table 3). Graphs were produced with the predicted CSD consumption by HDI (Fig. 3(a)) and GNIpc (Fig. 3(b)) by region, in which the top line representing Central and South America showed a considerable higher CSD consumption compared with other regions.
Multilevel model for carbonated soft drink consumption and HDI and logGNIpc
HDI, Human Development Index; GNIpc, Gross National Income per capita.
* P value < 0·01.
† Likelihood ratio test between null multilevel model and single model = 20·55 (> 3·84).
Predicted carbonated soft drink consumption by Human Development Index and Gross National Income per capita by region. (a) HDI, Human Development Index. (b) logGNI, Gross National Income per capita in logarithmic form. AFR, Africa; AMR, Central and South America; SEAR, Southeast Asia; EUR, Europe; EMR, Eastern Mediterranean; WPR, Western Pacific.
Discussion
The median prevalence of daily consumption of CSD and FV by adolescents in the countries surveyed were over 50 %, with major differences between countries and regions. The daily consumption of CSD was highlighted due to its significant variation between regions, and country levels of human development and income. The daily consumption of CSD was higher in Central and South America when compared with Africa, Eastern Mediterranean and Western Pacific, and among countries with higher HDI and GNIpc.
The comparison of our results with other adolescent health surveillance systems should be carried out with cautious, in view of the socio-cultural differences among the populations and the different methodologies adopted, including distinct time references to assess food consumption (last month or last week), established cut-off points and school grades. Taking this into consideration, adolescent health surveillance systems such as Health Behavior in School-aged Children (2014) in Europe and Canada(Reference Inchley31) and the Youth Risk Behavior Surveillance System (2017)(Reference Kann, McManus and Harris32), in the USA (and some territories such as Guam and Puerto Rico) obtained markedly lower prevalence of daily CSD consumption compared with those found in this study: 19·0 and 18·7 %, respectively(Reference Inchley31,Reference Kann, McManus and Harris32) .
In Health Behavior in School-aged Children, the daily CSD consumption tended to be associated with worse socio-economic conditions(Reference Inchley31), with the exception of some Eastern European countries. In these countries, with relatively lower HDI(28) and GNIpc(29) values compared with other European countries, CSD intake was higher among high-affluence adolescents(Reference Inchley31). These findings are consistent with the present work. Among countries with worse socio-economic conditions, it is assumed that as income increases and living conditions improve, the availability of ultra-processed foods, such as CSD, increases. This may be enhanced by the valuation of imported products and the gradual decrease in the price of these foods(Reference Monteiro, Moubarac and Cannon33,Reference Reardon and Timmer34) .
The high prevalence of daily CSD consumption shown in this study agrees with studies and reports that show an increasing trend in sweetened beverage consumption in countries with lower income(Reference Singh35–37). A study evaluating CSD consumption specifically in low- and middle-income countries through GSHS data indicated a similar prevalence of daily consumption of CSD to this study (54·3 %) and showed that adolescents consumed CSD, on average, 1·39 times/d, with a lower consumption in SEAR and a higher consumption in AMR(Reference Yang, Bovet and Liu38). In Mexico, the average daily consumption of CSD among adolescents aged 12–19 years reached 229·9 ml/d(Reference Malvido39).
Data from the National Health and Nutrition Examination Survey (2011–2014) in the USA showed that almost two-thirds of young people from 2–19 years old consumed at least one sugar-sweetened beverage per day (62·9 %)(Reference Rosinger, Herrick and Gahche40). Still, it is important to note that in recent years, the prevalence of CSD consumption has been significantly reduced in high-income countries(36). This scenario can be exemplified by data from the Health Behavior in School-aged Children, showing a reduction in daily CSD consumption of more than 20 % in countries such as Ireland, Israel, Slovenia, England and Scotland from 2002 to 2014(Reference Inchley31). Similarly, in Youth Risk Behavior Surveillance System, the percentage of adolescents who consumed CSD daily decreased from 33·8(Reference Kann, McManus and Harris32) to 18·7 %(Reference Miller, Merlo and Demissie41) (2007 to 2017). Although sales volumes in these countries remain high, these markets, in general, are saturated, which has led the CSD manufacturing industries to gradually shift and intensify their sales in middle- and low-income countries, especially in those whose economy is growing rapidly(Reference Singh35,36) , as in Central and South American countries.
The high CSD consumption in Central and South American countries compared with other regions was clearly shown in this study, in agreement with the literature(Reference Beal, Morris and Tumilowicz3,Reference Singh35,Reference Singh, Micha and Khatibzadeh42) . In this region, the expansion of large multinational companies, fast-food chains and supermarkets has led to a marked increase in the availability and consumption of ultra-processed foods, which tend to replace the healthy foods that are part of the local food culture(Reference Monteiro, Moubarac and Cannon33,Reference Reardon and Timmer34,Reference Yang, Bovet and Liu38) . Currently, three of the world’s top five CSD countries consumers are in Central and South America region(Reference Popkin and Hawkes43), which is considered the largest Coke producer in the world(36). In this region, the aggressive advertising strategies coupled with the transformation of food systems and the nutrition transition from traditional to Western diets have occurred in an accelerated way, constituting satisfactorily lucrative markets(Reference Monteiro, Moubarac and Cannon33,Reference Reardon and Timmer34,Reference Yang, Bovet and Liu38) . This scenario makes AMR occupies a prominent position as a region of particular concern for policy makers(Reference Singh35).
No association was found between FV consumption and macroeconomic indicators, although a trend of lower FV consumption was observed in countries with very high HDI and high income. In contrast, findings from the Health Behavior in School-aged Children showed a positive association between the prevalence of daily fruit consumption and socio-economic conditions, reported by about a third of respondents (33·0 %)(Reference Inchley31). These differences might be influenced by the countries composing these researches. The group with very high HDI in this study includes wealthy countries from the Eastern Mediterranean regions, such as Qatar and United Arab Emirates, with known lower FV consumption among adolescents when compared with other regions(Reference Al Ani, Al Subhi and Bose44). For the analysis of GNIpc, most high-income countries are from the Caribbean, such as Bahamas, Trinidad and Tobago, and Barbados. Caribbean countries are more vulnerable to natural disasters and disruptions of agriculture and food production systems, and therefore, they have their largest source of food from imported foods rather than national food production(Reference Kelly and Pemberton45,46) . This has contributed to the nutrition transition in these countries and the high import of ultra-processed foods, leading to some of the higher prevalence of obesity in the world. Also, these countries have high levels of income inequality and reduced food availability for some population groups(46).
In view of the nutrition transition and increased consumption of ultra-processed food, much has been discussed about ways to improve food and populations’ lifestyle. Global guidelines have emphasised the importance of adequate consumption of natural and minimally processed foods, such as FV, and the need to reduce ultra-processed foods intake, such as CSD(36,Reference Vereecken, Pedersen and Ojala47–50) . However, high rates of food inadequacy are still observed among adolescents, as indicated in this study. This scenario demands continuous attention to implement proposed guidelines and design new intersectoral and integrated strategies that contribute to improving adolescent living conditions.
To act effectively in this scenario, it is necessary to combine economic development programmes with political approaches aimed at improving the quality of food for individuals and populations. Among these, some measures are highlighted as options to prevent obesogenic environments through the regulation of food and beverage industries, such as the taxation of CSD; the regulation of publicity, especially those aimed at children and adolescents; the adoption of a front-of-pack food labelling that is easily understood by consumers and the regulation of ultra-processed foods in schools, limiting its commercialisation and advertising in their canteens and surroundings(Reference Kearney10,Reference Muhammad, D’Souza and Meade20,Reference Yang, Bovet and Liu38,Reference Darfour-Oduro, Andrade and Grigsby-Toussaint51,Reference Kessaram, McKenzie and Girin52) .
Moreover, there are actions to promote healthy environments such as the reduction of the stages of the food production chains; the incentive to FV consumption in schools; the provision of subsidies for the production and sale of fresh food, and when necessary, the strengthening of foods considered healthy imports(Reference Kearney10,Reference Muhammad, D’Souza and Meade20,Reference Darfour-Oduro, Andrade and Grigsby-Toussaint51) . These proposals reinforce the importance of adopting incisive political actions that in fact contribute to the improvement of the dietary pattern of the population in general, and especially among adolescents, which is reaffirmed by our results. Recent data show that adolescents living in countries with policies that encourage FV consumption are 1·48 times more likely to consume five portions of FV compared with adolescents in countries without such policies(Reference Darfour-Oduro, Andrade and Grigsby-Toussaint51). In addition, according to the WHO, the 20 % taxation on the costs of sweetened drinks can reduce consumption by about 20 %, with marked repercussions among families with lower socio-economic conditions(53).
In Mexico, for example, in the first 2 years of taxing sugar-sweetened beverages (1 peso/l) there was a 7·6 % decrease in household purchases(Reference Colchero, Rivera-Dommarco and Popkin54) with a greater reduction in households with children or adolescents(Reference Colchero, Molina and Guerrero-López55) and among those with high purchases of these drinks before taxation(Reference Ng, Rivera and Popkin56). Another example is Chile. One year after implementing the 5·0 % taxation of sugar-sweetened beverages, there was a 3·4 % decrease in volume purchased and 4·0 % decrease in energy content consumed(Reference Caro, Corvala´n and Reyes57). In addition, a direct assessment of sales points indicated a 5·8 % reduction in the affordability (estimated from consumer’s income, product and the price of other competing goods) of carbonated drinks after taxation(Reference Cuadrado, Dunstan and Silva-Illanes58). Although initial, these results are very important for Public Health, indicating possible ways for other countries that, together with other interventions, can intensify their fiscal policies to decrease sugar-sweetened beverages consumption(Reference Sánchez-Romero, Canto-Osorio and González-Morales59). Continuous monitoring of purchases and consumption of these drinks will be essential to better understand the long-term impact of this intervention model on populations health and nutritional status(Reference Caro, Corvala´n and Reyes57–Reference Sánchez-Romero, Canto-Osorio and González-Morales59).
Strengths
This study brings the novelty of a comparative evaluation of healthy and unhealthy food consumption markers among more than 250 thousand students from seventy-four countries in five different continents, and its association with different macroeconomic indicators. This study was conducted during school hours, which favoured higher response rates and greater knowledge about health among adolescents, who are less likely to search for care in health services(46).
Furthermore, our results indicate the relevance of developing and maintaining health surveillance systems to monitor food consumption markers and other risk factors for non-communicable diseases among adolescents, contributing to global efforts to generate robust evidence regarding adolescent food and nutrition. They also highlight the need to prioritise intersectoral public policies, which act to reduce social inequities(Reference Monteiro, Moubarac and Cannon33) and their potential consequences that contribute to disease prevention and health promotion in this population.
Study limitations
The study has some limitations that must be considered. First, the format of the GSHS consumption module responses (times/day in the last 30 d) may be difficult to respond, leading to overestimated answers. Second, the use of self-administered questionnaire may have caused underreporting or misunderstandings(Reference Camelo, Rodrigues and Giatti60). Still, it allows large-scale and fast data collection, which is important in international surveys. Third, the regions were not equally represented in the analysis due to the lack of data for macroeconomic indicators, and the lack of data on CSD consumption in twenty-four countries. Still, a significant association was found between CSD and macroeconomic indicators, showing the need to investigate this association in other populations and better qualify the data for more robust international comparisons.
Having this research performed in a school environment may had underrepresented adolescents in the most vulnerable situations and who are out of school, and therefore, data may be representative only of those who are regularly enrolled in schools(Reference Jacob, Stubbs and Firth61). Some regions have a significant proportion of adolescents out of school, and significant variations in school coverage (e.g. 39·7 % of adolescents do not attend school in West and Central Africa, and 7·5 % do not attend school in Latin America and the Caribbean)(62). Nevertheless, school-based surveys produce valid information, allowing large populations to be included with lower costs and more feasible logistics. Structural political actions that contribute to raising enrollment and school retention rates could further improve school survey results(49).
Conclusion
There was a high prevalence of daily CSD consumption among adolescents from mainly low- and medium-income countries. This prevalence was positively associated with HDI and GNIpc values, and mostly prevalent in countries from the Central and South American region, which are highly targeted by CSD manufacturing industries and ultra-processed food industry. The prevalence of daily FV consumption, although not associated with macroeconomic indicators and considered higher than in other surveys, must still improve to achieve the recommendations. These results point for the importance of public policies that regulate food and beverage industries and prioritise the consumption of FV among adolescents to avoid the increased prevalence of obesity and non-communicable diseases among adolescents and other age groups. To guide effective policies, further research is needed to quantify factors that promote the consumption of CSD among adolescents in different countries and regions.
Acknowledgements
The authors wish to thank the Pro-Rectory of Research, Federal University of Minas Gerais (PRPq/UFMG) for the assistance in the English revision of this manuscript.
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
N. L. F., S. B., R. M. C. and A. C. S. L. participated in the design of the study. N. L. F. and S. B. performed the statistical analysis, data interpretation and writing of the manuscript; R. M. C. and A. C. S. L. provided theoretical and statistical expertise. All authors revised and approved the final manuscript.
There are no conflicts of interest.
Supplementary material
For supplementary materials referred to in this article, please visit https://doi.org/10.1017/S0007114521001914
