N° 47 | July 2010

Promoting Consumption of Fruit: The Effects of Slicing Apples and Oranges in an Elementary School Cafeteria

Despite the documented health benefits of Fruit and Vegetable (F&V) consumption1, extensive data documents the underconsumption of these foods by Americans2-3. Serving millions of United States schoolchildren daily, school cafeterias offer important opportunities to improve produce consumption. School cafeterias need to explore ways of improving not only what is offered, but what is consumed by students. One possible option is to make already available healthy foods more accessible to students. This study compared the consumption of apples and oranges served in an elementary school cafeteria on a day they were served sliced versus a day they were served whole.

To measure student selection and consumption of fruit,

we used digital still photography to record every lunch served and eaten as part of the National School Lunch Program. Digital photography is highly reliable and precise means of measuring cafeteria consumption4-5. This approach can quickly collect large amounts of data from students without disrupting cafeteria operations. A unique identifier number is attached to each disposable lunch tray and a picture taken of each tray as the student exits the serving line and again before tray disposal. While trays were not associated with particular students, they were marked in a way to determine the grade level (K through 4) of the student. Following a procedure described elsewhere4, two analysts compared each pair of pictures and visually estimated the amount of each item selected and consumed. The two analysts’ estimâtes were averaged to create a single value for the quantity of each item consumed. The study then estimated the proportion of students eating at least half an apple or orange on each of the two study days using Clopper-Pearson exact 95% binomial confidence intervals. Differences between sliced and whole fruit consumption were considered meaningful if 95% confidence intervals did not overlap. The Relationship of age to fruit consumption was tested using logistic regression.

Whole apple and sliced orange

A lower percentage of students (6.8%) ate at least half an apple when sliced, compared to whole (6.8% vs. 8.9%), but the difference is not statistically meaningful, since the 95% confidence intervals overlap. In contrast, slicing oranges led to a significantly higher percentage of students selecting and eating at least half an orange (10.3% vs. 2.3%), a difference that is statistically meaningful. Additionally, the effect of slicing oranges was significantly greater among younger students than among older students. For example, almost 18% of Kindergarten students ate half an orange or more when sliced, compared to just over 2% for whole oranges. The difference in orange consumption rates for fourth graders, however, was not significant.

Slicing : an idea to increase F&V consumption

Because this was a purely observational study, we can only speculate on why slicing oranges would increase consumption, while slicing apples does not. It is telling that the impact of slicing on consumption was particularly important for younger students. Oranges, which can be difficult to peel in the short time given to students for lunch, were more accessible when sliced and significantly more students selected and consumed oranges when they were offered in sliced form. Whole apples, we speculate, are easier to eat than unsliced oranges. This study demonstrates that relatively simple, low cost changes in the way food is presented to students can have significant effects on the selection and consumption of healthy food choices. Carefully considering the convenience and accessibility of food items could help cafeteria personnel increase healthy eating by students. However, our findings demonstrate that it cannot be assumed that an action to make one food item more accessible - such as slicing - will have the same effect on another food item.

  1. Dietary Guidelines Advisory Committee. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans: 2005. In. Washington, DC: US Department of Agriculture, Agricultural Research Service; 2004.
  2. U.S. Department of Agriculture. MyPyramid. Available at: mypyramid.gov. Accessed February 16 2009.
  3. National Cancer Institute. Usual Dietary Intakes: Food Intakes, US Population, 2001-04. Available at: http://riskfactor.cancer.gov/diet/usualintakes/pop/. Accessed May 15 2010.
  4. Swanson M. Digital Photography as a Tool to Measure School Cafeteria Consumption. Journal of School Health 2008;78(8):432-437.
  5. Williamson DA, Allen R, Martin PD, Alfonso AJ, Gerald B, Hunt A. Comparison of digital photography to weighed and visual estimation of portion sizes. Journal of the American Dietetic Association 2003;103(9):1139-1145.
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