Abstract

Increasing rates of obesity among children ages 12 to 19 years have led to recommendations to alter the school food environment. The purpose of this study was to determine whether there are associations between an altered school food environment and food choices of middle school students both in and outside of school. In a midsized western city, two of six middle schools allowed only bottled water in vending machines, only milk and fruit on à la carte menus, and offered a seasonal fruit and vegetable bar. Three years after the intervention was initiated, seventh- and eighth-grade students attending the two intervention schools and four control middle schools were surveyed about their food choices. A total of 2,292 surveys were completed. Self-reported frequency of consumption for nine food groups in the survey was low; consumption was higher outside than in school. Boys consumed more milk than girls although girls consumed more fruits and vegetables. Significant socioeconomic differences existed. Compared with students who paid the full lunch fee, students qualifying for free and reduced-price meals consumed more milk and juice in schools but less outside school; more candy and energy drinks in school; and more sweet drinks, candy, pastries, and energy drinks outside school. Students in intervention schools were 24% more likely to consume milk outside school, 27% less likely to consume juice in school, and 56% less likely to consume sweet pastries in school. There were no differences in fruit and vegetable consumption reported by children in control and intervention schools. Overall, there was a positive association between a modified school food environment and student food behavior in and outside school. Policies related to the school food environment are an important strategy to address the obesity epidemic in our country.

Methods

Results and Discussion

A total of 2,292 surveys (response rate 55.6%) were returned from seventh- and eighth-grade students in intervention and control schools. Intervention schools represented 26% of respondents, whereas the control schools (four of six middle schools) represented 74%. Response rates for control (87.4%) and intervention (82.4%) schools were similar. Boys (51%) and girls (49%) were equally represented among respondents.

Overall, students self-reported low consumption for all nine categories of food on the food frequency survey and reported higher frequency of food consumption outside school than inside school ( Table 1 ). This is consistent with reports that children in this age group under-report food consumption ( 14 ) and consume more food outside school than in school ( 1 ). The food most frequently consumed was milk; however, only one fourth reported at least two servings of milk per day outside of school; 14% reported consuming at least two servings of milk daily in school. Sweetened drink consumption was lower in this survey than reported in other studies ( 12): medium to high frequency of consumption of sweetened beverages was reported by 12% to 18% of students in school and 20% to 30% outside school. More than three fourths of students in this study reported low consumption (less than one serving per day) of chips, candy, pastries, and energy drinks; this may be a reflection of the school wellness policies that the school district implemented before our study.

Table 1

Seventh- and eighth-grade children’s differences in food choices in and outside school, by sex and meal status ^a

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a The numbers of observations reported in the second row are approximate because they might vary due to missing data across different food items. Results are from Kruskal-Wallis equality-of-proportions rank tests. Low=0-4 servings/wk (less than 1/d); Medium=5-6 servings/wk (1/d); High=2-3 servings/d.

⁎ P <0.05.

⁎⁎ P <0.01.

For the combined control and intervention group clear sex differences in the frequency of self-reported food choices were identified ( Table 1 ). Boys consistently reported more frequent milk consumption in and outside school compared with girls. In school 17.1% of boys consumed two or more daily servings of milk compared with 11.3% of girls, and outside school 25.3% of boys consumed two or more daily servings compared with 21.0% of girls. Girls reported more frequent consumption of fruits and vegetables than boys outside school. Nearly 26% of girls consumed at least two fruits per day outside school compared to 21.3% of boys, and 19.4% of girls consumed at least two vegetables per day outside school compared with 16.7% of boys. Boys consumed more juice, sweet drinks, and pastries at school than girls.

For the combined groups significant income differences were noted for student frequency of consumption of several food items in and outside of school ( Table 1 ). Milk consumption by students receiving free and reduced-price meals was higher than that by students receiving fully-paid meals in school; however, students with fully-paid meals consumed more milk outside of school. Students receiving free and reduced-price meals reported consuming more juice at school than students who paid for their meals; they also consumed more candy and energy drinks in school and more sweet drink, candy, pastries, and energy drinks outside of school. This may support the conclusion drawn by Drewenoski and Darmon ( 15 ) that lower-income families choose foods that provide high energy return for the cost.

Significant differences were identified between intervention and control schools ( Table 2 ). The ordered logistic regression that controlled for sex, meal status, and location of food item consumption showed that students in intervention schools were 56% less likely to consume pastries and 27% less likely to consume juice, which was the only energy-dense vended beverage in control schools. This demonstrates that modifying the school food environment likely has a positive influence on the foods that students consume. Students at intervention schools were 24% more likely to consume milk outside of school. It may be because the limited beverage options at intervention schools created a taste preference for milk at home. It was surprising that fruit and vegetable consumption reported by students at the intervention schools was not significantly better than those students in the control schools because seasonal fruit and vegetable bars were available to all students in intervention schools regardless of whether they purchased a school meal. Fresh fruits and vegetables were available to all students in control schools on the meal line. Van Cauwenberghe and colleagues ( 16 ) also reported that fruit and vegetable intake was not affected by changes in school food environment.

Table 2

Consumption differences by seventh- and eighth-grade children (n=2,000) between intervention and control schools ^{a b}

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a The numbers of observations reported in the first row are approximate because they might vary due to missing data across different food items. Results are from ordered logistic regressions. The ordered logistic regression analysis was conducted using STATA 10 (2007, Stata Corp, College Station, TX).

b Independent variables in each regression analysis are sex, school meal status, and consumption of the same food item in the complementary location.

The findings of this study present a conundrum for school administrators. Findings demonstrated that healthful modifications in the school food environment are associated with positive food behaviors in early adolescents, but there was a cost associated with those changes. Each intervention school spent 49% more on produce per student than control schools during the 2008-2009 and 2009-2010 school years (spending about $2,500 more per school per year), and annually both schools together lost approximately $24,000 in gross school meal sales due to lost à la carte sales and a $9,000 annual loss in vending sales. The pressures to provide more nutritious, often more costly foods to students in the midst of shrinking budgets and unfunded mandates makes it difficult to eliminate profitable competitive foods.

Conclusions

This study identified a positive association between reported student food choices and a modified food environment. School food polices and the food environment can be part of a long-term solution to the youth obesity problem. Practitioners in school nutrition need to work with key decision makers to offer a healthful school food environment. Especially school meal programs in lower income areas need to be encouraged and promoted because of the key nutrients provided by school meals.

Findings of this study are limited due to lack of ethnic/racial diversity among respondents, the fact that the study relied on self-reported frequency of food choices, and knowledge that it was administered in a health and fitness class. Future research should include more objective measures of food behavior. In addition, longitudinal research is needed to assess food behaviors before and after a school food environment intervention to determine the causal effect of changes in the school food environment on food behaviors among adolescents.

STATEMENT OF POTENTIAL CONFLICT OF INTEREST: No potential conflict of interest was reported by the authors.

FUNDING/SUPPORT: This project was supported by National Research Initiative grant no. 2006-04637 from the US Department of Agriculture’s National Institute for Food and Agriculture Teen Eating and Activity Mentoring in Schools program .

ACKNOWLEDGEMENTS: The authors thank Washington State University, especially the team at the College of Nursing, whose commitment to excellence in research and support of partnerships and scholarly work made this article possible.

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