Total Pageviews

Saturday, August 2, 2014

School lunches: Measure twice - cut once

“History doesn’t repeat itself, but it does rhyme” Mark Twain

Maureen Ogle, in her book “In meat we trust”, reminds us that school lunches have always been on the menu of food controversies. In 1926, the New York School Board banned frankfurters from school lunches. She writes that: “The board’s lunch director explained that the food was unsuited to students’ nutritional needs” The director went on to say that: “The sausage was so heavy that when children ate it, they neglected to eat green stuff and milk”. And you’ve guessed it – no data were gathered upon which to construct evidence based policy. The director simply looked into his or her heart in search of wisdom. The issue of school lunches lingers on and whilst I want to end on a positive note, I will cite three studies which all show that poorly informed or misinformed interventions in food choice to improve nutritional balance in school lunches can back fire.

Case 1. A group from Tufts University examined the effect of three years of intervention in the US National School Lunch Programme to reduce total fat and saturated fat intake[1]. They observed that as the % of calories in lunches decreased, the % of calories from fat increased. This is known as the sugar-fat seesaw. Basically, if one reduces the level of fat in a child’s energy supply, children will compensate for the loss of fat by eating higher amounts of other foods and time after time, it has been shown that as you lower fat, you raise sugar. So, in today’s terms where sugar is popularly perceived to be utterly toxic, would one describe the reduction in total fat and saturated fat intakes as a success or would the increase in % energy from sugars be seen as a failure. This writer would deem it a success as fats and especially saturates are directly implicated in elevated plasma cholesterol on the basis of dozens of randomised controlled feeing studies while almost none exist for sugar at the normal or even slightly normal levels of intake.

Case 2. Fruit and vegetable intake are common targets in school lunch programmes and the general belief is that because they have a low energy density (fewer calories per unit weight) that higher intakes will reduce energy intake. Researchers from the University of Wiscanson-Maddison studied food choice in school canteens using digital imaging to identify foods selected and portion size[2]. They studied schools taking part in the Farm to School project. They found that whereas fruit and vegetable intake increased, the intake of other foods decreased such that energy intake remained constant. Thus if the objective was to reduce energy intake, the project failed. But a higher intake of low-salt, low fat fruit and vegetables would reduce overall the negative targets of foods (fats, saturates etc.) and thus the project should be deemed a success.

Case 3: Brian Wansink and his colleagues at Cornell University, reported on a pilot study evaluating the consequences of banning chocolate milk in school cafeterias[3]. Chocolate flavoured milk represents about two thirds of all mile in the US school cafeteria system. In 11 Oregon schools, chocolate flavoured milk was banned from the lunch menu and the group from Cornell used data gathered in the National School Lunch Program to assess the success or otherwise. Total milk sales fell by 10%. White milk increased but some 29% of this non-flavoured milk was wasted, that is unfinished by the students. In all, the numbers of children using the School Lunch Program fell by 7%. Success or failure? Once again I would say the outcome could have been predicted if someone had invested funds in attitudinal research, which would have saved a lot of money and effort. My father, a carpenter, always used the phrase: “Measure twice – cut once”. In effect, these school lunch managers, in all three cases never measured even once. But they were all mad keen to cut!

Which brings us to a major recent study from the University of Chicago, which carried out a survey of 557 representative schools to assess the impact of the updated standards of the National School Lunch Program[4]. The ratio of “agree”/ “agree strongly” to “disagree”/ “disagree strongly” that “students generally seem to like the new school lunch” was about 70:30. This contrasts with the opinion: “At first, students complained about the new lunch” where 57% agreed or agreed strongly. So, slowly the students absorbed the newer healthier lunches. About 2/3 students have fewer complaints about the new lunches and the same number doesn’t seem concerned about the changes. One main area of complaint was the withdrawal of pizzas from some school menus. Students were happy with healthier pizzas but not happy with the absence of any pizza option. So this is a positive note for innovation school lunches. However, the more that innovation is built on a priori data, the more likely it is to be successful and, regrettably, the general trend is to cut and not measure in advance.

Here in the EU, where national policies on school lunches differ according to member state, the Commission has published a very useful overview of existing practices and has set the scene for future joint action to help improve the nutritional quality of school lunches[5].

One area of public health nutrition that is badly missing is the measure of the impact of school lunches on the student’s overall daily dietary performance. In other words, for how many children does the school lunch counter balance poor dietary practices at home and outside the home and school environments? For how many pupils is the home driving most the student’s daily intake of nutrients to optimal. Such data are very important to understand the true social impact of school lunches.

[1] Dwyer JT et al (2003) Journal of Adolescent Health, 32, 428435
[2] Bontrager Yode AB et al (2014) Childhood Obesity July 2, e-pub ahead of print
[3] Hanks AS et al (2014) PLOS ONE, 9, (4), e91022
[4] Turner L and Chaloupka FJ (2014) Childhood obesity, 10, number 4

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.