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Limited intake of energy, fruit, vegetables, and dairy product among children eating at public elementary schools

Daniel J. Hoffman, PhD
Associate Professor
Department of Nutritional Sciences
Rutgers, the State University of New Jersey
26 Nichol Avenue, New Brunswick, NJ 08901

Cheryl Jacko
Rutgers, the State University of New Jersey

Karen Ensle EdD, RD, FADA, CFCS
Rutgers, the State University of New Jersey

Abstract

The objective of this study was to determine the amount of energy and macronutrient composition of foods consumed by children attending public elementary schools. We conducted an observational study using indirect methods of assessing food intake of children in the public schools of an urban area of New Jersey. The main measurements of our study were energy intake; percent of energy as fat, carbohydrates, and protein; proportion of food served and consumed; and proportion of USDA recommended daily servings that were consumed at lunch. Students t-test was used to determine differences between variables and we used SPSS for Windows version 13.0 for all analyses.

We found that the amount of energy consumed at lunch was less than 500 Kcal, and the macronutrient composition followed USDA recommendations. Limited amounts of fruits and vegetables were consumed at lunch, and children consumed approximately 35 percent of their estimated daily energy needs at lunch. In addition, less than 50 percent of any food serving, as recommended by the USDA, was consumed. Thus, we conclude that the amount of food energy children eat at schools is unlikely to promote a positive energy balance. In addition, the fact that children are consuming a small proportion of healthful foods at school suggests that improvements can be made in school lunch programs to promote the intake of fruits, vegetables, and dairy products.

Since childhood overweight is of great concern in the United States and most children attend public schools, the need for increased awareness as to what children are actually eating at school is warranted. The results of our observational study suggest that there is room for improvement in terms of both encouraging and educating children to eat a variety of healthful foods and promoting the intake of healthful foods through improved school lunch programs. While it is recognized that administrative and fiscal constraints may inhibit such improvements, the future health of our nation is dependent upon having healthy children today.

Key words: Schools, diet, children, plate-waste

Introduction

Currently, 16 percent of children below the age of 18 in the United States are overweight, while 31 percent are considered at risk for overweight (Dehghan, Akhtar-Danesh, and Merchant 2005). This trend in childhood overweight and obesity has been increasing dramatically over the past 20 years and has resulted in an increased incidence of type II diabetes and hypercholesterolemia in children (Callahan and Mansfield 2000; Boney, Verma, Tucker, and Vohr 2005). Therefore, studying controllable factors that may increase a child’s risk for becoming overweight or obese is a priority for both health and nutrition professionals.

Many factors, including race, socio-economic status, parental weight, physical activity, and diet contribute to a child’s risk for becoming obese (Winterfeld 2005; Crespo et al. 2005; Dietz 1991; Goran and Treuth 2001). For example, opportunities to engage in physical activity, either during or after school, have decreased as budgets are cut and/or neighborhoods become less safe (Molnar and Livingstone 2000). Thus, no one of these factors individually contributes to a child’s risk for becoming overweight, but rather the convergence of these key factors contributes to a positive energy balance, resulting in an increased BMI for age.

In particular, one dietary factor that has received considerable media attention, but with little or no empirical evidence, is the food served at schools. Recently, many media venues have discussed how school food programs can be modified to prevent or reverse the trend in childhood overweight. At the same time, food served at schools has become another cause for alarm given the increase in purchases of foods and beverages not part of the school lunch meal, such as chips, cookies, snack cakes, and soda. While some schools and school districts have instituted a ban or modification of foods and beverages sold in vending machines, much criticism is still placed upon foods sold during lunch programs (Yeoman 2003).

Still, very little is known about what children actually consume at lunch while they are in school. Since almost all children in the United States attend school, and many of these children eat breakfast and/or lunch at school, it is important to understand exactly how much and which foods are consumed at school. Thus, we conducted a study to determine the amount of energy consumed during school lunch and the macronutrient composition of foods actually consumed in public schools in central New Jersey.


Methods

Location
Two elementary schools were selected in Elizabeth, New Jersey, and measurements of food intake were conducted for grades 3, 4, and 5. The schools were selected based on the extent of cooperation from the principals and foodservice workers within the district. The menus for each school were similar, following the National School Lunch Program’s (NSLP) nutritional guidelines and using foods from the same vendor.

Methodology
This study was an observational study of food intake among children attending public elementary schools. The aggregate “plate waste” method was used to estimate the mean caloric consumption during lunch (Comstock, St Pierre, and Mackiernan 1981). Macronutrient composition of what was actually consumed and percent waste of the different components of the meals were estimated, along with the percentage of lunch calories contributing to the mean predicted total energy expenditure. Collection of plate waste occurred over a two-month period, with unannounced visitation for a total of eight days in each school. A combined total of 455 lunch trays were sampled during this period. As this study was conducted in a public elementary school system, no foods were available for purchase by the students outside of food items served in the cafeteria.

Data collection involved having a research assistant visit each school on a randomly chosen day at the beginning of the lunch period. The trays for all students were prepared by the lunch staff and no changes to any dining hall practices or procedures were made during the data collection. A sample of three trays was used to determine the amount of each food served to the students. Following lunch, students were asked to stack their trays on a particular cart where the trays were counted and any food items remaining on the plates were collected in plastic containers. The foods that were left were then weighed on a digital gram scale to calculate the total mass of each food item that was not consumed. The average amount of food wasted was calculated as the mass of wasted food divided by the number of trays studied.

The percentage of plate waste was determined for each food item and grouped accordingly as grains, milk, fruit and vegetable, or entrée, and then averaged over the study period to determine the mean percent waste for each category. Nutritional analysis of the mean amount of food consumed by each child was performed using Nutritionist Pro® to calculate the daily energy and macronutrient content provided by each school lunch assessed.

Estimation of the mean total energy expenditure for the children studied was done using the Harris-Benedict prediction equation (Finan, Larson, Goran 1997). Briefly, the resting metabolic rate was predicted using the mean weight, height, and age of the classes studied and multiplied by a factor of 1.4 for activity, given that the children did not participate in organized sports or engage in physical activity during the school day. Percent contribution of lunch calories to predict total energy expenditure was calculated using the mean lunch caloric value determined by the nutritional analysis. Differences between the amount of foods served and the estimated consumption were analyzed using students T-test and SPSS for Windows 12.0 (SPSS Inc., Chicago, Illinois). Statistical significance was set at p = 0.05. Height and weight data on all students in grades 3, 4, and 5 were obtained from the school nurse.

Results

Results on the comparison of energy and food intake of the school children measured are presented in Tables 1 through 4. Total caloric intake and macronutrient intake are listed in Table 1 while the percent of the daily energy needs of the children are presented in Table 2. The estimated caloric intake of the children for both schools was 470 kilocalories (Kcal) per lunch, and the proportion of macronutrient intake was 19 percent protein, 49 percent carbohydrate, and 32 percent fat (Table 1). The estimated total energy expenditure of the children studied was 1,753 Kcal. Thus, approximately 27 percent of their daily needs were being met by the foods they consumed at lunch (Table 2).

The actual amount and percent of food served that was consumed are listed in Table 3.

In terms of actual food consumption, it was found that 26 percent of the entrees served were not consumed by the students. Approximately 61 percent of fruits and vegetables were discarded and almost 50 percent of milk was not consumed. For dessert items, approximately 62 percent of the dessert items offered was not consumed (Table 3).

Table 4 contains data on the proportion of servings consumed compared to the servings recommended by the USDA. Comparing the proportion of servings for foods as promoted by the USDA Food Guide, we found that half to less than half of any one food serving was consumed by the students (Table 4). In particular, about 33 percent of any fruit serving was consumed, 50 percent of any vegetable serving was consumed (regardless of whether it was starchy or non-starchy), and 50 percent of any milk serving was consumed.

Discussion

While many of the causal factors for childhood overweight, such as low levels of physical activity, high intake of fat- and energy-dense foods, or having parents who are overweight or obese, have been identified, the role of school foods in this causal pathway has been studied in only a few studies, one of which was specific to Native Americans and not generalizable to the U.S. population as a whole (Addison, Jenkins, White, and Young 2006; Caballero, Clay, Davis et al. 2003). Food consumed at school – in particular, foods provided by the school in contrast to foods purchased outside of school or from vending machines – has received negative criticism in the nutrition literature as well as the popular press (Harrison and Peggs 2002; Morse 2002; Bedford 2006; Tam, Garnett, Cowell et al. 2006). However, these criticisms are generally provided with little or no empirical evidence. Thus, the aim of our study was to determine (1) how many calories do children consume when they eat school food, and what is the macronutrient composition of the foods they eat; and (2) how much of a child’s estimated total energy needs are met by food consumed in school.

Briefly, the mean energy intake of the children we studied was approximately 500 Kcal per child. This estimate was approximately 35 percent of the estimated total energy needs of the children. Similar results were found in a study of energy and macronutrient intake of elementary school children (Whatley, Donnelly, Jacobsen et al. 1996). However, in a more recent NSLP study using the same methodology, the mean energy consumed by elementary students at lunch was 570 Kcal (Lee, Lee, and Shanklin 2001), approximately 100 Kcal higher than our results. Thus, based on prediction equations for energy needs, children are not consuming an excess amount of energy at lunch.

The observations made through our study suggest that aspects of food intake other than school lunch or physical activity are more likely to be related to the current trend in childhood obesity. For example, while children may not be consuming “excess” calories at lunch, it is important for future studies to determine the quality of foods that are consumed. Also, the dining environment is key to food intake patterns given the fact that if dining time is limited, only those foods that are easiest to eat will be consumed. It is worth exploring how the timing of dining influences overall intake and quality of foods consumed. Likewise, if children are eating too early or too late in the school day, food intake will differ. Finally, if proper timing for physical activity is not allowed during the school day, some children may make use of the lunch period to be active, even if through fidgeting at a table, in lieu of eating, creating a potential source for excess consumption of snack foods after school or before dinner.

In addition, it was found that while the mean total energy served during lunch varied by approximately 100 Kcal, the estimated energy consumed remained constant. This would suggest that the portion size of the foods provided did not influence the energy consumption of NSLP lunches. It has been suggested that a positive association between energy intake and palatability exists (McCrory, Saltzman, Rolls, and Roberts 2006), indicating that foods that are perceived to taste better are more likely to be consumed. Thus, if children perceive school foods to be unpalatable, or time to consume the food is too short, it is not unreasonable to conclude that their energy intake would be lower than expected. A caveat to these findings is the possibility that some children may exceed their daily energy needs if all foods at lunch are consumed. Based on our data, given that we were using less than accurate methods to assess energy intake and available energy, and daily energy requirements of each student, it is difficult to speculate as to how likely it is that eating all items of a school lunch could promote obesity in some children. The fact remains that any one person may become obese simply through a positive energy balance of 50-100 Kcal/day. Determining the exact source of these extra calories, be it at breakfast, lunch, snacks, dinner, or some aspect of being sedentary, is virtually impossible.

In terms of children’s eating habits and their overall risk for becoming overweight or obese, there are several implications of our results. First, a limitation of our study was that we were working in a lower income school district, and it is not known what the diet of each child consisted of when outside of school or at home. Still, aside from generalizing our results to other schools, it is clear that the students we studied were not consuming an excess proportion of their daily calories during lunch. Second, the schools studied were providing a balance of foods with daily offerings of fruit, vegetables, and dairy products. Third, we did not have the option of individually calculating the energy needs for energy intake for each child given the logistical and ethical constraints of conducting such measurements. Nonetheless, we were able to provide at least an estimate of how the energy consumed at lunch is related to the estimated energy needs of children, but we were unable to report on specific items wasted due to logistical constraints. Finally, students may very easily consume some food (nutritious or not) before they attend school, bring snack foods with them to school, eat snack foods or fast foods on their way home, and so on. Still, the focus of this study was to determine how much children actually eat during lunch at school.

The major policy implication of this study is that a renewed interest in surveillance and interventions of school lunch programs is urgently needed. The original goal of school lunch programs was to provide safe, nutritious foods to prevent nutritional inadequacies (Frank, Vaden, and Martin 1987). This goal appears to have been accomplished in many states, and it may still be the goal for some areas of the United States. However, with the recent increased prevalence of childhood overweight, there is a great need to ensure that students are not only exposed to safe, nutritious foods that prevent excess energy intake (Bell and Swinburn 2004), but that these foods are actually desirable and palatable so that children can develop a natural and healthful appreciation of fruits and vegetables. Without this development, it is highly unlikely that children will become adults who enjoy fruits and vegetables. Thus, it should be the goal of nutrition and health professionals, as well as school staff and administrators, to ensure that all children are exposed to a healthful diet and have the educational background to understand the importance of eating healthful foods.

A secondary policy implication of our findings relates to the nutritional and economic cost of “wasting” foods that are purchased and served by our schools and provided to our children. It is no secret that the cost of school foods is a major part of any school system’s budget, not to mention the additional cost for personnel and infrastructure. In addition, it is worth noting that children may experience some nutritional deficit if nutrient dense foods are the primary foods wasted. These two issues are very important, and our data appear to suggest that even a macro-analysis of foods served by schools can be useful in shaping future purchasing policies if it can be determined when specific items (e.g., canned vegetables, whole fruits, etc.) or certain classes of food (e.g., white milk, cheese, chicken, etc.) are not consumed. This would allow professionals to reassess purchasing policies and design menus that are more likely to be consumed, without sacrificing the nutritional quality of lunches provided to students. Future studies could include modifying aspects of foods served, allowing more time for food to be consumed, or having focus groups with students that would allow for direct input by the students on school food programs.

Conclusions

Based on the results of this study, children eating school lunches in public schools do not appear to be consuming an excess number of calories or an excess amount of fat, relative to their energy needs. In addition, the proportion of USDA recommended servings of fruit, vegetables, and dairy products consumed by school children is low, suggesting that improvements in school lunches can be made to promote more healthful diets.

Table 1: Estimated energy intake between schools studies

Variable

Mean of two schools

served

consumed

Total energy (Kcal)

722 ± 167

479 ± 147

Protein (g)

31.9 ± 7.1

21.4 ± 4.5

Protein (%)

18.0 ± 4.2

18.6 ± 4.6

Carbohydrate (g)

99.6 ± 26.5

59.1 ± 19.2

Carbohydrate (%)

54.6 ± 4.5

49.0 ± 3.9

Fat (g)

22.2 ± 6.2

17.6 ± 7.5

Fat (%)

27.5 ± 4.4

32.4 ± 5.4

Extra-snack purchases (Kcal)

N/A

12 ± 7

Condiments (Kcal)

N/A

10 ± 2

 

Table 2: Mean height, weight, predicted daily energy expenditure, and percent total energy expenditure consumed of children attending two public schools in central New Jersey

Variable

Mean

Height (cm)

139.4 ± 3.5

Weight (kg)

39.9 ± 27.1

Predicted total energy

expenditure (Kcal/day)

1753

% total energy expenditure consumed

27

 

Table 3: Mean percent waste of foods served at two public schools in Elizabeth, New Jersey

Variable

Mean of two schools

Portion size

Plate waste (%)

Entrée

5.2 ± 1.1

26.1 ± 13.1

Fruits & vegetables

1.5 ± 0.3*

60.6 ± 31.4

Milk

8.0 ± 0

49.1 ± 14.4

Special treats

2.8 ± 9

62.4 ± 17.1

 

Measurement based on USDA Food Guide Pyramid servings

Table 4: Average daily Food Guide Pyramid serving offered and consumed

Food categories

Mean of schools A and B

Served

Consumed

Fruits and vegetables

1.5 ± 0.3

0.6 ± 0.2

Fruit

0.7 ± 0.4

0.2 ± 0.2

Vegetables, total

0.8 ± 0.2

0.4 ± 0.3

Vegetables, starchy

0.4 ± 0.2

0.2 ± 0.1

Vegetables, non-starchy

0.4 ± 0.2

0.2 ± 0.3

Milk

1 ± 0

0.5 ± 0.1


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Cite this article

Daniel J. Hoffman, Cheryl Jacko, and Karen Ensle. 2008. Limited Intake of Energy, Fruit, Vegetables, and Dairy Product Among Children Eating at Public Elementary Schools. The Forum for Family and Consumer Issues, 13 (2).

On-line: http://ncsu.edu/ffci/publications/2008/v13-n2-2008-summer-fall/index-v13-n2-summer-2008.php

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