Revista Oficial do Núcleo de Estudos da Saúde do Adolescente / UERJ
NESA Publicação oficial
ISSN: 2177-5281 (Online)
|Original Article|| Imprimir
Páginas 63 a 72
Autores: Raquel Raizel1; Allan da Mata Godois2; Valdemar Guedes da Silva3; Mariano Martínez Espinosa4; Amélia Dreyer Machado5; Sebastião Junior Henrique Duarte6; Christianne de Faria Coelho Ravagnani7
1. Doctoral student, Graduate Studies Program in food Science, School of Pharmaceutical Sciences, São Paulo University (USP). São Paulo, São Paulo State
How to cite this article
Keywords: Fruit, vegetables, adolescent.
Insufficient consumption of fruit and vegetables fosters to the appearance of diseases such diabetes, obesity and high blood pressure, which are leading causes of death among adults1. Data from the National School Health Survey indicate low consumption of fresh vegetables (43.4%) and fruit (30.2%) among Brazilian schoolchildren 2. According to the World Health Organization, the consumption of these foods by adolescents falls below the daily recommendations (400g), with a greater likelihood of nutritional shortfalls with adverse effects on their development1. Due to the above-mentioned health problems, actions encouraging healthy eating have become a priority for public policies all over the world3.
However, in order for these actions to be effective, it is necessary to identify the factors associated with eating attitudes, in addition to the contexts that surround them. Eating behaviors among adolescents are related to family income, gender, place of residence and head-of-family education levels4-6. These factors may function distally, indirectly influencing fruit and vegetable intake, while others such as tobacco use, alcohol intake, physical activity levels and the number of meals5,6 constitute the proximal dimension, whose influence may be direct7.
These factors may be organized into theoretical models that analyze multi-causality affecting health-related behaviors, as ecological models that assume the existence of multiple dimensions of influence and inter-relationships among them7-9. It is believed that individual behaviors may be affected in many different ways, such as: individual /intrapersonal (lifestyle, emotional factors); interpersonal (influence of family and friends); physical context (community, school) and the macro-system (media, social standards)7. Nevertheless, although it is well understood that food intake is multi-factorial, most investigations focus on one or two dimensions of influence10.
This survey starts out from the assumption that studies addressing only one dimension, such as intra-personal relationships, do not clearly demonstrate the determining factors leading to inadequate eating habits, as they fail to consider the context within which this behavior is established. Consequently, it is necessary to investigate multiple influences in order to understand factors that enable and hamper healthy eating7, in order to design interventions spurring behavioral changes. The objective of this study was to analyze fruit and vegetable intake by adolescents and explore the associated factors through an ecological approach that considers multiple dimensions of influence.
A cross-sectional study was conducted in the Mato Grosso State capital in 2011, with male and female adolescents between 12 and 19 years old living in Cuiabá and registered with the Family Health Strategy (ESF) units working with the Education for Health Work Program (PET Saúde). This survey was approved by the Ethics Committee for Research involving Human Beings at the Júlio Müller Hospital (Protocol Nº 693/2009).
Located in Center-West Brazil, this municipality is divided geographically into four regions (South, North, East and West). The Education for Health Work Program is implemented in nineteen Family Health Strategy (ESF) units, covering all these regions. The urban population of this municipality reaches 540,814 inhabitants11 and, according to preliminary surveys, 10,596 adolescents were registered at nineteen ESF units. However, adolescents living in regions not assisted by Community Health Agents (ACS) were not included, with 7,014 adolescents registered for sampling purposes.
In order to calculate the size of the sample, the following aspects were taken into consideration: population of 7,014 adolescents; 95%; Confidence Interval acceptable sampling error of five percentage points and estimated prevalence of 50%, as there is no knowledge of this parameter, which allows a larger sample to be defined in order to establish accuracy. Based on these parameters, the necessary sample size was 364 adolescents. An additional 20% was added to cover possible losses and refusals, as well as controls for confounding factors. Consequently, the final sample was established at 437 adolescents.
The sample selection was probabilistic, stratified sampling was used by ESF units, so that the representative figures for each unit of the population remained constant in the sample. Population elements were organized through the ESF datasheets (Datasheet A) by rising order of micro-regions covered by the Education for Health Work Program, selected systematically.
Adolescents were rated as eligible with no physical or mental disabilities preventing completion of the questionnaire; who agreed to participate voluntarily in the study; who were located within three visits on alternating days; and with authorization from parents or guardians. The formal agreement of these adolescents and their parents or guardians (for participants under 18 years old) was confirmed through signatures of Deeds of Informed Consent.
The tool used was adapted from the basic questionnaire used for the Global School-Based Student Health Survey conducted by the World Health Organization (WHO). This tool consists of ten modules (eating and sexual behaviors; drugs, alcohol, tobacco use; hygiene; mental health; physical activity; protective factors; non-intentional injuries and violence) with questions added on the relationship and involvement of these adolescents with healthcare teams and the ESF.
The results of the study were defined as inadequate intake of fresh fruit / juice and vegetables (< once a day). The independent variables were grouped into blocks as follows:
Block 1 - Distal Factors
Social and economic factors
Family income (3 or more minimum wages or ≤ 2 minimum wages);
Gender (female or male);
Nutrition education actions, undertaken by the ESF (Yes or No);
Block 2 - Intermediate Factors
Receiving parental support (Yes or No);
Block 3 - Proximal Factors
Drinking alcohol during the past thirty days (Yes or No);
Psychosocial Stress Indicators
Feeling sad during the past twelve months (Yes or No);
In order to test the hypothesis that there is a complex relationship between inadequate fruit and vegetable intake and multiple influencing factors, the hierarchized models strategy was adopted, as proposed by Victora9. A conceptual model was developed (Figure 1) with an ecological approach. It was considered that factors in the upper Block (social, economic, demographic conditions, and community context) could influence fruit and vegetable intake either directly or be mediated by factors in the lower Blocks (social context), or proximal factors (lifestyle and psychosocial stress indicators).
Figure 1. Conceptual model of the ecological approach developed in order to analyze fruit and vegetable intake among adolescents in Mato Grosso State.
The Blocks were then tested in the distal and proximal modes in terms of results, with the effect of each variable on the outcome is construed as adjusted for variables belonging to hierarchically preceding Blocks (more distal) and for the effects of variables in the same Block. The bivariate and multivariate analyses were conducted through the STATA statistical package version 10.0 (Stata Corp., College Station, USA).
The bivariate analysis was run through Pearson´s chi-squared test, calculating the Gross Prevalence Ratio (PRg) and Confidence Intervals (CI) at 95%. In order to obtain the Adjusted Prevalence Ratio (PRa) Poisson´s multiple regression technique was used. Associations with a p value of <0.20 in the bivariate analysis were used as entry criteria for the multivariate models.
The variables were inserted into the model Blocks by order of significance, with the initial phase modelling within each Block (distal, intermediate, proximal). Only variables with p value of <0.10 remained in the final model for each Block. Three models were obtained (distal, intermediate and proximal), and during the second phase the intermediate model variables were added to the Distal Block model (model 1+2). The third phase consisted of inserting the proximal model variables into the previous Blocks model (model 1+2+3).
Having included variables from the other model, associations obtaining a p value of >0.10 were maintained, interpreting the association as existing but mediated by an added Block. In the final model, only associations with a p value of less than 0.05 were rated as significantly associated with inadequate fruit and vegetable intake.
In the final sample, the respondents consisted of only 399 adolescents, as 38 declined to participate or returned blank questionnaires. However, the final sample still remained higher than the initial figure (364 adolescents). Of the 399 respondents, 37 were unable to provide information on family income. More than half the sample was female (63%), between 15 and 19 years old (62%), with family incomes ≤ 2 minimum wages (54%) and maternal education levels of ≥8 years of study (53%). Most (93%) of the adolescents were not engaged in paid work and approximately 55% did not receive any type of government aid (Table 1).
Table 1 presents the prevalence of inadequate fruit and vegetable intakes, as well as the ratios for this situation. No statistically significant differences were noted for the social, economic and demographic factors, nor community context, participation in the Health Program for Young People and Adolescents, feeling sad and lifestyle-related variables: alcohol intake, smoking tobacco and physical inactivity.
Some 34% of the adolescents reported inadequate fruit and vegetable intakes. In the gross analysis, this prevalence was significantly higher for adolescents reporting no parental support (41%) and not having close friends (49%), compared to those stating that they received parental support when taking decisions (25%) and had close, intimate friends (32%), respectively. Inadequate fruit and vegetable intakes were also associated significantly with the absence of vegetable gardens at home (p = 0.006), shortages of food at home (p = 0.009), factors related to psychosocial stress such as thinking about or attempting suicide (p = 0.005) and feeling worried to the point of losing their appetites during the past twelve months (p = 0.028).
The second column in Table 2 shows the hierarchical regression model for each Block. The third column presents the intermediate model consisting of Block 1 (physical context) and Block 2 (social context). The final model is presented in column 4, with the inclusion of Block 3 (individual context). Adolescents who had not received health education were more likely to report inadequate fruit and vegetable intakes. However, this association did not remain significant when adjusted for factors related to the social context.
After the adjusted analysis, adolescents reporting that they did not receive parental support, did not have kitchen gardens at home and were subject to food shortages at home presented a higher prevalence of inadequate fruit and vegetable intakes. No significant associations were noted between inadequate fruit and vegetable intakes and the absence of close friends, nor thinking about or attempting suicide. In the final model, only variables related to the social context (Block 2) were significantly associated with the results. However, the isolated global effects of each factor must not be discarded, in terms of explaining the outcomes (Table 2).
Approximately 34% of the adolescents reported inadequate fruit and vegetable intakes, with this prevalence being higher among those not receiving health education and parental support, reporting the absence of kitchen gardens and food shortages at home, and those with symptoms of psychosocial stress. These results indicate the complexity of the factors involved in fruit and vegetable intake and the need to adopt approaches that take multiple influences into consideration.
The findings of this study corroborate the literature, which highlights factors related to social and physical contexts as potentially determining food intake among adolescents12. The social context is closely linked to the autonomy of youngsters for making healthy eating choices10. In this study, the absence of parental support contributed negatively to fruit and vegetable intakes. Families influence the formation of healthy eating habits among adolescents and attitudes related to fruit intake 13.
The absence of parental support may portray family structures that in turn are reflected in emotional aspects of their offspring. Adolescents from families with non-traditional structures were at greater risk of eating only small quantities of vegetables14. Fulkerson et al.15 ascertained that family influence is inversely associated with symptoms of depression in adolescents. Described here as thinking about or attempting suicide, these symptoms directly influence fruit and vegetable consumption rated as inadequate.
Psychosocial stress indicators may be mediated by factors in higher dimensions, such as food insecurity. Food shortages associated with low fruit and vegetable intakes is an important aspect of this study, as it reflects a situation of food insecurity. However, it is known that the adoption of a good quality diet is inversely correlated to food prices16. It is thus necessary to investigate the priority given to food purchases, as other food groups may be assigned higher priority in the homes of these adolescents, in situations constituting food insecurity, instead of buying fruits and vegetables which are expensive.
Food intake is also influenced by availability 17. In the study by Souza et al.18, adolescents reported the easy availability of unhealthy foods at home, leading to their consumption. In this study, adolescents who reported that they did not have vegetable gardens at home also indicated a higher prevalence of inadequate fruit and vegetable intakes. Along these lines, initiatives encouraging the cultivation of these foods, in addition to emphasizing the value of regional and seasonal produce may also lead to better availability of healthy foods and consequently higher fruit and vegetable intake.
The actions of schools in producing information that help adolescents take decisions is of the utmost importance. The absence of classroom actions was significantly associated with inadequate fruit and vegetable intakes among the adolescents in this study. Although the influence of classroom actions has not been widely investigated, this is an important target for interventions using food-related approaches. After a three-year intervention modifying the dietary context in a school, Wordell et al.19 found a significant improvement in the eating habits of pupils at the school and elsewhere.
Although some of the explanatory variables have not been explored in detail, in this study it was possible to ascertain the factors contributing largely to inadequate fruit and vegetable intakes among adolescents. Significant associations were found in more than over dimension of their life context. This consequently confirms the importance of approaches such as those suggested by Stokols8 and Story et al.7, which suggests the cumulative impact of social, physical and cultural aspects on health-related behaviors in specific contexts.
Along these lines, multi-dimensional approaches are vital for successfully modifying contexts in more than aspect, thus reshaping individual behaviors10. Encouragement for family farming and strengthening nutrition and diet-related actions at all healthcare levels are addressed in the National Nutrition and Food Security Plan20. However, the development of intervention strategies related to these points requires fine-tuning and greater effectiveness.
Although the cross-sectional structure of this study does not allow causality to be inferred in the associations, the approach adopted indicated a complex relationship among these adolescents in terms of behaviors, context and fruit and vegetable intakes. The use of a self-reporting tool may under-estimate or over-estimate reported intake frequency. However, as it is developed and recommended by the WHO, the GSHS is adopted in epidemiological studies in many countries, and was useful in this study for providing data on health-related behaviors among adolescents.
Inadequate fruit and vegetable intake is a matter of concern, particularly among adolescents not receiving health education and parental support, as well as those reporting food shortages and the absence of kitchen gardens at home, together with attempting or thinking about suicide. Programs designed to build up family capabilities for planting and maintaining kitchen gardens at home may well step up fruit and vegetable intakes, while strengthening personal and inter-personal relationships and boosting family incomes. Finally, schools and families must be included in the set of actions designed to encourage higher fruit and vegetable consumption among adolescents.
Financial support received from the National Health Fund, Ministry of Health.
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