Interdisciplinary Educational Interventions Improve Knowledge of Eating, Nutrition, and Physical Activity of Elementary Students

This research aimed to evaluate the interdisciplinary educational intervention effects on knowledge of eating, nutrition, and physical activity in elementary-school students. Participants were 368 school children enrolled in public schools. The research was organized in three stages: pre-intervention, intervention and post-intervention. In pre-intervention, children were evaluated regarding their nutritional status. They also answered questionnaires related to eating and nutrition and physical activity. In the intervention stage, educational interventions were carried out on the same topics for a period of five months; in post-intervention, children answered the same questionnaires applied in pre-intervention. Despite most children having normal nutritional status (58.2%), a high number of students were overweight (38%). In the initial phase, it was found that most children had excellent knowledge of eating, nutrition, and good physical activity knowledge (p-value < 0.05). Educational health intervention significantly increased children’s knowledge of eating, nutrition, and physical activity, when evaluated in the post-intervention period. Both boys and girls increased their knowledge of eating, nutrition, and physical activity after the application of interdisciplinary interventions (p-value < 0.05). A similar effect was observed for children with different nutritional status. It is concluded that interdisciplinary educational interventions carried out for children in an elementary-school environment are effective for improving knowledge of eating, nutrition, and in physical activity, promoting healthier habits among children.


Introduction
Obesity results in an energy imbalance between caloric food consumption and caloric expenditure. Currently, more than 650 million adults are obese, representing 13% of the global population. In relation to children, it is estimated that 340 million children aged between 5 and 19 years old and 40 million children under 5 years old are overweight [1]. In Brazil, overweight and obesity has increased by 239% in 20 years, with 15% of school children and adolescents (6 to 18 years old) being diagnosed with overweight and 5% with obesity [2].
Childhood obesity has immediate and long-term consequences for health in addition to strongly predicting nutritional status in adulthood [1]. One of the factors that contributes to increased obesity worldwide prevalence is the nutritional transition process. This process is determined by systemic social changes, such as increased industrialization, urbanization academics in the fields of nutrition and physical education. Figure 1 shows a detailed study stages flowchart.

Population
Research was carried with a representative sample of total number of children (9600) of school age (7-10 years), enrolled between the 2nd and 5th grades in 36 public schools in an urban area. Sample determination was carried out in two stages: (1) the schools were selected by means of non-probabilistic sampling for convenience, the one with the largest students number being chosen, thus totaling 18 schools; (2) children were chosen through simple random sampling, considering the following parameters-total number of students enrolled in the 2nd to 5th grades of urban schools in the city, a confidence level of 95% and maximum error of 5%, totaling a minimum representative sample of 368 students.

Pre-Intervention Stage
At this stage, children answered two questionnaires, one about knowledge about eating and nutrition and other about knowledge about physical activity.

Eating and Nutrition Knowledge
Eating and nutrition questions (ENQ) were based on content presented in the Food Pyramid Guide [30]. Thus, it aimed to verify knowledge about food groups. The questionnaire consisted of four general illustrative multiple-choice questions belonging to food pyramid groups: Question 1 (ENQ 1)-"Which foods have more carbohydrate?"; Question 2 (ENQ 2)-"Which foods have enough vitamins and minerals?"; Question 3 (ENQ 3)-"Which foods have more protein?"; Question 4 (ENQ 4)-"Which foods have a lot of sugar and/or fat?". Each question had eight alternatives, of which only four were correct. Children were classified as follows: "low knowledge" (0 to 5 points), "good knowledge" (6 to 10 points) and "great knowledge" (11 to 16 points) [31]. The eating and nutrition knowledge questionnaire showed satisfactory internal validity (Cronbach's alpha, α = 0.74) [32].

Physical Activity Knowledge
An instrument on knowledge of physical activity, with an approach to exercising importance for health, was developed based on questionnaires by Domingues et al. [33] and Silveira and Silva [34]. Its purpose was to investigate children's understanding of physical activity benefits for health, prevention of chronic disease and their effects on human body. The Physical Activity Questions (PAQ) consisted of a questionnaire with four general illustrative multiple-choice questions: Question 1 (PAQ 1)-"Physical activity performed daily prevents which these diseases?"; Question 2 (PAQ 2)-"Can exercise lack leads a person to have?"; Question 3 (PAQ 3)-"What the practice physical activity improves on a daily basis?"; Question 4 (PAQ 4)-"What activities can help you to have good health?". Each question had eight alternatives, of which only four were correct. Children were classified as follows: "low knowledge" (0 to 5 points), "good knowledge" (6 to 10 points) and "great knowledge" (11 to 16 points) [31]. The physical activity knowledge questionnaire showed very good internal validity (Cronbach's alpha, α = 0.81) [32].

Intervention Stage
Health education activities related to eating, nutrition, and physical activity topics were applied in an interdisciplinary way by professionals and academics in nutrition and physical education areas. Interventions were carried out for five months, with two meetings per month, totaling ten meetings per school. Each intervention lasted a total Nutrients 2022, 14, 2827 5 of 15 of 30 min. The first 15 min were used to explain the topics covered, then expository and participatory activities were carried out. The exercises were carried out in interspersed and individual meetings, with respect to each knowledge area. After the theoretical explanation, a practical dynamic was applied, reinforcing theoretical knowledge. Activities were aimed at providing students with an identification and reflection of problems, raising hypotheses and pointing out solutions to a reduce sedentary lifestyle. In this way, educational and dynamic lectures were included, using simple language, which helps with fixing and understanding the content. Throughout the educational process, active participation and interaction with students was prioritized.

Eating and Nutrition Actions
Recreational-educational activities relating to eating and nutrition were prepared according to the Food Pyramid Guide [30], which visually represents food concepts such as proportion, moderation and variety. Topics covered were food groups; food and its different functions in the body; and recommended daily portions [30]. This intervention aimed to build, with children's help, the pyramid levels from previous explanations, encouraging the consumption of lower caloric foods and greater intake of foods with a high nutrient content, promoting a healthy and varied diet. All interventions related to eating and nutrition were carried out in classrooms and in the schoolyard, facilitating learning.

Physical Activity Actions
Actions were based on content covered in guidelines [35,36] and manuals [37]. Materials included physical activity recommendations for children and adolescents, including information on quantity, types and intensity, health benefits, and encouragement for the daily practice of activities and games. In addition, topics related to occasional problems caused by physical activity were considered, especially a sedentary lifestyle in childhood and prolonged use of electronic devices, such as cell phones, computers, video games and television. Also, the outdoor children's games practice that, rescued popular culture and body movement, such as running, jumping and walking, was encouraged. The intervention objective was to make students aware of regular exercise, both in a school environment and outside, in addition to promoting interactive activities between groups. Actions were carried out in specific places at school, such as the physical education court. Table 1 describes activities related to eating, nutrition, and physical activity carried out in schools.

Post-Intervention Stage
Questionnaires applied in pre-intervention stage were reapplied at this stage to assess the learning effect from educational actions (intervention stage) on knowledge about eating, nutrition, and physical activity.

Statistical Analysis
Results were evaluated using mean frequency and standard deviation, depending on the case. Nutritional assessment was performed using Epi Data program (Data Management and Basic Statistical Analysis System, version 3.1, Odense, Denmark). To perform the analyses, R software, version 4.0.3, was used, using descriptive procedures and inferential statistics. Nonparametric tests-Pearson's and Wilcoxon's chi-square tests-and parametric tests-paired Student's t test and Tukey's test-were used to evaluate data. A significance level of 5% (p-value < 0.05) was adopted for analyses.

Ethical Issues
Research was approved by the Ethics Committee for Research Involving Human Beings (COMEP) of UNICENTRO, under opinion No. 3089,447/2018.

Post-Intervention Stage
Questionnaires applied in pre-intervention stage were reapplied at this stage sess the learning effect from educational actions (intervention stage) on knowledge eating, nutrition, and physical activity.

Statistical Analysis
Results were evaluated using mean frequency and standard deviation, dependi the case. Nutritional assessment was performed using Epi Data program (Data Ma ment and Basic Statistical Analysis System, version 3.1, Odense, Denmark). To pe the analyses, R software, version 4.0.3, was used, using descriptive procedures and ential statistics. Nonparametric tests-Pearson's and Wilcoxon's chi-square testsparametric tests-paired Student's t test and Tukey's test-were used to evaluate d significance level of 5% (p-value < 0.05) was adopted for analyses.

Ethical Issues
Research was approved by the Ethics Committee for Research Involving Huma ings (COMEP) of UNICENTRO, under opinion No. 3089,447/2018.

Nutritional Status Assessment
The children had a mean age of 8.65 ± 0.8 years, with 8.6 ± 0.8 years for girls an ± 0.7 years for boys. The BMI mean was 18.3 ± 3.8 kg/m 2 , differing between girls (17.9 kg/m 2 , eutrophy-≥3rd percentile and ≤85th percentile) and boys (18.7 ± 4.0 kg/m 2 , weight->85th percentile and ≤97th percentile), considering mean age for each ge Figure 2 shows the participant nutritional status. Most children presented eutrophic nutritional status. However, a high numb students were classified as overweight (38%) for age and gender [43], corroborating studies carried out in China [44], the United States [45] and Italy [46]. In Brazil, s results were observed in the northeast [47] and southeast [48]. In addition to geneti behavioral factors, such as diets and sleep duration, socioeconomic factors, family ronment and food preferences are also associated with the prevalence of childhood sity [49]. The environment can also influence nutritional status, as demonstrated by al. [50]. In addition, authors also assessed the quality of children's food received at s and at home, using the US Department of Agriculture Food and Nutrient Databa Most children presented eutrophic nutritional status. However, a high number of students were classified as overweight (38%) for age and gender [43], corroborating other studies carried out in China [44], the United States [45] and Italy [46]. In Brazil, similar results were observed in the northeast [47] and southeast [48]. In addition to genetic and behavioral factors, such as diets and sleep duration, socioeconomic factors, family environment and food preferences are also associated with the prevalence of childhood obesity [49]. The environment can also influence nutritional status, as demonstrated by Au et al. [50]. In addition, authors also assessed the quality of children's food received at school and at home, using the US Department of Agriculture Food and Nutrient Database for Dietary Studies (version 3.0, USDA, Beltsville, MD, USA, 2008). They concluded that Nutrients 2022, 14, 2827 7 of 15 meals offered in a school environment had better overall quality compared to those offered at home. This fact can directly interfere with a child nutritional status. This reinforces the importance of expanded educational actions that promote healthier food consumption. Table 2 shows the children's response prevalence to questionnaires about their knowledge of eating, nutrition, and physical activity in the pre-and post-intervention stages. Regarding the pre-intervention stage, most children had excellent knowledge of eating and nutrition and good physical activity knowledge (p-value < 0.05). A smaller percentage was classified as having low knowledge in both subjects. These results demonstrate that participants had some prior knowledge about eating, nutrition, and physical activity before receiving educational intervention. Schools and advertising media are increasingly concerned with educating children about the importance of physical activity and nutrition to prevent chronic diseases and improve quality of life [51].

Evaluation of Pre-and Post-Intervention Stages
After educational health actions (post-intervention), almost all children showed excellent knowledge both in eating, nutrition, and in physical activity, which demonstrates the effectiveness of this eating and nutrition education for this population, corroborating other studies [52,53]. In addition, recreational activities aimed at promoting health are considered a great opportunity to create relationships that favor sharing of knowledge and experiences, instructing the individual to take care of their own health [51]. According to Drapeau et al. [54], nutritional education can also improve healthy food consumption. Figure 3 shows the medians of correct responses for children in the pre-intervention and post-intervention periods, in relation to the knowledge of eating and nutrition, and physical activity, respectively.
Health education activities carried out during the intervention stage increased children's knowledge of eating, nutrition, and physical activity in the post-intervention period (p-value < 0.05). Similar effects were observed by Franciscato et al. [53] and Syrmpas et al. [55] after interventions carried out in schools with children in Brazil and Greece, respectively. In this respect, the school environment is ideal for carrying out preventive health education actions due to its structure, effectiveness and wide coverage of individuals [56]. In addition, studies have already shown that these interventions can positively influence fruit and vegetable consumption, nutritional knowledge, energy and sugar intake [57] and physical activity [26].  Health education activities carried out during the intervention stage increased children's knowledge of eating, nutrition, and physical activity in the post-intervention period (p-value < 0.05). Similar effects were observed by Franciscato et al. [53] and Syrmpas et al. [55] after interventions carried out in schools with children in Brazil and Greece, respectively. In this respect, the school environment is ideal for carrying out preventive health education actions due to its structure, effectiveness and wide coverage of individuals [56]. In addition, studies have already shown that these interventions can positively influence fruit and vegetable consumption, nutritional knowledge, energy and sugar intake [57] and physical activity [26]. Figures 4 and 5 show the median correct responses for children in relation to eating, nutrition, and physical activity in pre-and post-intervention stages, separated by gender and nutritional status, respectively. Both boys and girls increased their knowledge of eating, nutrition, and physical activity after interdisciplinary intervention application (pvalue < 0.05). A similar effect was observed when children were evaluated in nutritional status terms, which was not observed in the study by Franciscato et al. [53]. It is noteworthy that nutritional knowledge may not be directly related to actual dietary practices. Thus, despite children having adequate knowledge about the effects of unhealthy diets on health, they continue to consume them [58]. In this aspect, it is possible that the effective change in eating habits is influenced by other factors, such as family environment [59], advertising [60], the socioeconomic conditions of those responsible [21] and children's interaction with friends and teachers [19]. The same occurs with physical activity practice, since awareness of its importance can promote positive change in behavior in relation to physical activity in this age group [26].   5 show the median correct responses for children in relation to eating, nutrition, and physical activity in pre-and post-intervention stages, separated by gender and nutritional status, respectively. Both boys and girls increased their knowledge of eating, nutrition, and physical activity after interdisciplinary intervention application (p-value < 0.05). A similar effect was observed when children were evaluated in nutritional status terms, which was not observed in the study by Franciscato et al. [53]. It is noteworthy that nutritional knowledge may not be directly related to actual dietary practices. Thus, despite children having adequate knowledge about the effects of unhealthy diets on health, they continue to consume them [58]. In this aspect, it is possible that the effective change in eating habits is influenced by other factors, such as family environment [59], advertising [60], the socioeconomic conditions of those responsible [21] and children's interaction with friends and teachers [19]. The same occurs with physical activity practice, since awareness of its importance can promote positive change in behavior in relation to physical activity in this age group [26].    Correct answers to questions about knowledge of eating, nutrition, and physical activity in the pre-and post-intervention stages, considering the children's genders. * Indicates significant difference by Wilcoxon Test (p-value < 0.05), in relation for correct answers to questions of the questionnaires about knowledge in eating, nutrition, and physical activity in the pre-and post-intervention stages. The assessment was performed between the same gender. Grade scale: 1-low, 2-good, and 3-great. Children's knowledge level regarding eating, nutrition, and physical activity in preand post-intervention stages, considering gender and nutritional status, can be seen in Table 3. Evaluating the knowledge topic in eating and nutrition in the pre-intervention stage, it is observed that most female and male children with nutritional status of eutrophic and overweight presented excellent knowledge. Few participants (≤7%) were assessed with low knowledge. Children's responses with low weight showed no difference between good and excellent knowledge (p-value > 0.05), and none were classified as having low knowledge. Regarding physical activity, most underweight and eutrophic boys had good knowledge, while girls and overweight children were considered to have excellent knowledge (p-value < 0.05). Similar to what happened in the topic of eating and nutrition, a lower children number, regardless of gender and nutritional status, were classified as having low physical activity knowledge relating to health (≤18%). Children's knowledge level regarding eating, nutrition, and physical activity in preand post-intervention stages, considering gender and nutritional status, can be seen in Table 3. Evaluating the knowledge topic in eating and nutrition in the pre-intervention stage, it is observed that most female and male children with nutritional status of eutrophic and overweight presented excellent knowledge. Few participants (≤7%) were assessed with low knowledge. Children's responses with low weight showed no difference between good and excellent knowledge (p-value > 0.05), and none were classified as having low knowledge. Regarding physical activity, most underweight and eutrophic boys had good knowledge, while girls and overweight children were considered to have excellent knowledge (p-value < 0.05). Similar to what happened in the topic of eating and nutrition, a lower children number, regardless of gender and nutritional status, were classified as having low physical activity knowledge relating to health (≤18%).
At post-intervention stage, excellent knowledge of eating and nutrition, regardless of gender and nutritional status (p-value < 0.05), was observed for most children. It is noteworthy that a very low number of participants (≤0.7%) had good and low knowledge in this topic. Additionally, all underweight children had excellent knowledge. As for the approach to physical activity, most children had excellent knowledge, except for one female and one with low weight who were classified as having good knowledge. In this context, playful educational interventions aimed at health can help in the learning process, relating theory to practice [55]. Furthermore, interdisciplinary educational actions improved children's responses in terms of excellent knowledge (>90%) on topics of eating, nutrition, and physical activity (Table 3), an effect also observed in research by Fuller et al. [61] with Danish children. Figures 6 and 7 show correct answer averages to questions about eating and nutrition knowledge in pre-and post-intervention stages, compared between genders. Regarding the pre-intervention stage, boys were less assertive than girls (p-value < 0.05) for sugar and/or fat group (ENQ 4). At the post-intervention stage, there was no significant difference between genders for all questions. As for knowledge about physical activity (pre-intervention), boys scored less correctly than girls in all questions (p-value < 0.05). A similar effect occurred after intervention for questions PAQ 2 and in total assessment of responses; however, there was no significant difference (p-value > 0.05) to questions PAQ 1, PAQ 3 and PAQ 4. According to Jalkanen et al. [62], girls are generally more concerned with their body weight. In addition, they suffer social and family influences and demands for a thin body, factors that may explain the greater female knowledge of topics addressed in this research.   Table 4 shows children's correct answer averages comparing pre-and post-intervention stages, in relation to knowledge of eating, nutrition, and physical activity. At the preintervention stage, ENQ 2, ENQ 4 and PAQ 4 questions were ones in which participants scored the most correct answers (p-value < 0.05), while ENQ 1, PAQ 1 and PAQ 2 questions had fewer correct answers (p-value < 0.05). Generally, children have greater preference and acceptance for foods with high sugar and fat levels [63], and less when it comes to fruit and vegetables [64]. They also have high knowledge level about the sugar content present in foods [60] and about the importance of fruit and vegetable consumption and their health effects [65]. However, their choices are based on availability and accessibility of food purchased by family members, advertising and preferences [60]. This context may explain children's greater knowledge of these topics. the importance of consuming healthy foods and reducing sugar and fat intake, in addition to promoting physical exercise. In Brazil, this topic is regulated by the National School Eating Program (Programa Nacional de Alimentação Escolar-PNAE), which aims to meet the nutritional needs of children at school and form healthy eating habits through food and nutrition education [67]. Another piece of legislation deals with the School Health Program (Programa Saúde na Escola-PSE), which aims to contribute to students wellbeing through actions of promotion, prevention and healthcare [68].   [66], which recommends health education for children, guardians and teachers, including the importance of consuming healthy foods and reducing sugar and fat intake, in addition to promoting physical exercise. In Brazil, this topic is regulated by the National School Eating Program (Programa Nacional de Alimentação Escolar-PNAE), which aims to meet the nutritional needs of children at school and form healthy eating habits through food and nutrition education [67]. Another piece of legislation deals with the School Health Program (Programa Saúde na Escola-PSE), which aims to contribute to students wellbeing through actions of promotion, prevention and healthcare [68].  Average of correct answers to questions about knowledge about physical activity in preand post-intervention stages, compared between genders. * Means indicate significant difference by Student's t test (p-value < 0.05) in the same question. Physical Activity Questions (PAQ): PAQ 1-"Physical activity performed daily prevents which these diseases?"; PAQ 2-"Can exercise lack leads a person to have?"; PAQ 3-"What the practice physical activity improves on a daily basis?"; PAQ 4-"What activities can help you to have good health?"; Each question contained 4 correct answers; for the total there were 16 correct answers. Figure 7. Average of correct answers to questions about knowledge about physical activity in preand post-intervention stages, compared between genders. * Means indicate significant difference by Student's t test (p-value < 0.05) in the same question. Physical Activity Questions (PAQ): PAQ 1-"Physical activity performed daily prevents which these diseases?"; PAQ 2-"Can exercise lack leads a person to have?"; PAQ 3-"What the practice physical activity improves on a daily basis?"; PAQ 4-"What activities can help you to have good health?"; Each question contained 4 correct answers; for the total there were 16 correct answers.
When individual answers at post-intervention stage are evaluated, it is verified that the proposed knowledge of foods with carbohydrate (ENQ 1), protein (ENQ 3), what lack of exercise can cause (PAQ 2) and what are the benefits of daily physical activity practice (PAQ 3) were the questions that had less effectiveness in children's learning (p-value < 0.05). Despite this, educational activities in eating, nutrition, and physical activity increased children's knowledge of all questions (p-value < 0.05), which are corroborated by the literature [52].
Considering the positive effects observed by interdisciplinary interventions applied in the present research, it can be inferred that results can contribute to increase food consumption with favorable nutritional profile in childhood. Thus, it corroborates the WHO [66], which recommends health education for children, guardians and teachers, including the importance of consuming healthy foods and reducing sugar and fat intake, in addition to promoting physical exercise. In Brazil, this topic is regulated by the National School Eating Program (Programa Nacional de Alimentação Escolar-PNAE), which aims to meet the nutritional needs of children at school and form healthy eating habits through food and nutrition education [67]. Another piece of legislation deals with the School Health Program (Programa Saúde na Escola-PSE), which aims to contribute to students wellbeing through actions of promotion, prevention and healthcare [68]. ; ENQ 2-"Which foods have enough vitamins and minerals?"; ENQ 3-"Which foods have more protein?"; ENQ 4-"Which foods have a lot of sugar and/or fat?"; Physical Activity Questions (PAQ): PAQ 1-"Physical activity performed daily prevents which these diseases?"; PAQ 2-"Can exercise lack leads a person to have?"; PAQ 3-"What the practice physical activity improves on a daily basis?"; PAQ 4-"What activities can help you to have good health?".

Conclusions
Eutrophic nutritional status was verified for most school-aged children; however, a high number of these children are overweight for their age. In general, children have good knowledge of topics related to eating, nutrition, and physical activity. This knowledge is enhanced after carrying out educational health interventions, when applied in an interdisciplinary manner and for a prolonged period of time. This effect was observed for boys and girls and when children were organized by different nutritional status. However, boys stand out for having less knowledge, especially in specific subjects related to physical activity. Finally, it is concluded that educational health interventions applied in an interdisciplinary way in the school environment are effective for improving knowledge in eating, nutrition, and physical activity, promoting healthier habits among children.