Advertisement

Location of School Lunch Salad Bars in Cafeterias: Design and Analysis Issues

      To the Editor:
      Letters to the Editor are Welcome
      Letters to the Editor may be submitted at http://ees.elsevier.com/andjrnl for consideration regarding manuscripts published within the past 6 months. Letters should be no more than 500 words, can contain up to 20 references, and should include a funding disclosure, conflict of interest disclosure, and copyright/authorship form. All letters will be subjected to editorial review and decision before acceptance.
      Adams and colleagues
      • Adams M.A.
      • Bruening M.
      • Orhi-Vachaspati P.
      • Hurley J.C.
      Location of school lunch salad bars and fruit and vegetable consumption in middle schools: A cross-sectional plate waste study.
      described a novel study examining the placement of salad bars within six middle school cafeterias as it relates to students’ consumption of fruit and vegetables (F/V). The authors found that students selected and consumed more F/V when salad bars were offered as part of the lunch line as compared to when the salad bars were located outside of the line. While these findings are consistent with both theoretical and empirical evidence,
      we are concerned with several aspects of the study design and analysis of data.
      The current study has an unbalanced design in terms of the F/V options served on the day of data collection. All three schools with salad bars outside of the line served potatoes and juice. In contrast, only one school with salad bar on the line served potatoes, and no schools with a salad bar as part of the line served juice.
      Potatoes and juice are generally not included in public health recommendations because they are already frequently consumed.
      • Lorson B.A.
      • Melgar-Quinonez H.R.
      • Taylor C.A.
      Correlates of fruit and vegetable intakes in US children.
      However, they are counted as F/V components of the National School Lunch Program (NSLP).

      US Department of Agriculture Food and Nutrition Service. USDA’s New Meal Pattern in Schools. July 2013. http://www.fns.usda.gov/sites/default/files/Mealpatternppt.pdf. Accessed March 11, 2016.

      Given children’s preference for these items, they may compete with other F/V options served at school lunch. Ideally, data collection days would be selected a priori to balance the F/V options served across schools.
      The posteriori exclusion of potato and juice as F/V options from the analysis is misleading, as these items are not counterbalanced with the position of the salad bar. In the text, 20.7% of students (49 of the 237) from schools with the salad bar outside the lunch line consumed any F/V. Yet as shown in the Figure, this is really 91% of the 54 students that self-served any non-potato non-juice F/V. This is similar or possibly significantly higher than the 83% of students that consumed any F/V when the salad bar was inside the lunch line.
      In addition, all three schools with the salad bar inside the line had more fruit options and fewer vegetable options. Not counting potatoes and juice, national data show children eating more servings of fruits than vegetables,
      • Kim S.A.
      • Moore L.V.
      • Galuska D.
      • et al.
      Vital signs: Fruit and vegetable intake among children—United States, 2003-2010.
      probably because of preference for the sweet taste of fruits.
      • Ventura A.K.
      • Mennella J.A.
      Innate and learned preferences for sweet taste during childhood.
      Research has also shown that a variety of options further increase selection.
      • Rolls B.J.
      • Rowe E.A.
      • Rolls E.T.
      • Kingston B.
      • Megson A.
      • Gunary R.
      Variety in a meal enhances food intake in man.
      • Just D.
      • Wansink B.
      Better school meals on a budget: Using behavioral economics and food psychology to improve meal selection.
      The unbalanced number of fruit vs vegetable options between the two groups further confounds the independent variable.
      Since potato and juice items were part of the choice architecture of the lunch line, we suggest the authors re-analyze the selection and consumption data with and without counting them as F/V. If possible, we also suggest analyzing the selection and consumption data for fruits, vegetables, and salad bar options separately, while controlling for the number of options within each category. This would clarify whether students selected and ate more salad bar items (eg, a true positive), differentiating from F/V offered on the standard menu, that are often times pre-plated on lunch trays.
      We applaud the authors in their novel inquiry and hope that our concerns are well received.

      References

        • Adams M.A.
        • Bruening M.
        • Orhi-Vachaspati P.
        • Hurley J.C.
        Location of school lunch salad bars and fruit and vegetable consumption in middle schools: A cross-sectional plate waste study.
        J Acad Nutr Diet. 2016; 116: 407-416
      1. Roberto C.A. Kawachi I. Behavioral Economics and Public Health. Oxford University Press, New York, NY2015
        • Lorson B.A.
        • Melgar-Quinonez H.R.
        • Taylor C.A.
        Correlates of fruit and vegetable intakes in US children.
        J Am Diet Assoc. 2009; 109: 474-478
      2. US Department of Agriculture Food and Nutrition Service. USDA’s New Meal Pattern in Schools. July 2013. http://www.fns.usda.gov/sites/default/files/Mealpatternppt.pdf. Accessed March 11, 2016.

        • Kim S.A.
        • Moore L.V.
        • Galuska D.
        • et al.
        Vital signs: Fruit and vegetable intake among children—United States, 2003-2010.
        MMWR Morb Mortal Wkly Rep. 2014; 63: 671-676
        • Ventura A.K.
        • Mennella J.A.
        Innate and learned preferences for sweet taste during childhood.
        Curr Opin Clin Nutr Metab Care. 2011; 14: 379-384
        • Rolls B.J.
        • Rowe E.A.
        • Rolls E.T.
        • Kingston B.
        • Megson A.
        • Gunary R.
        Variety in a meal enhances food intake in man.
        Physiol Behav. 1981; 26: 215-221
        • Just D.
        • Wansink B.
        Better school meals on a budget: Using behavioral economics and food psychology to improve meal selection.
        Choices. 2010; 24: 1-6

      Linked Article