January, 2012

Research Perspective and Comments & Analysis

National School Lunch Program Shows Promising Progress

By USDA's Food & Nutrition Service

Editor’s Note: In September, 2011, the USDA’s Food and Nutrition Service (FNS) published its first interim report on the progress of the nation’s School Lunch Program. The following is an excerpt of the report, which is available in its entirety at http://www.fns.usda.gov/ora/MENU/Published/CNP/FILES/FFVPInterim.pdf


The Fresh Fruit and Vegetable Program (FFVP) aims to increase fruit and vegetable consumption among students in the nation’s poorest elementary schools by providing free fresh fruits and vegetables to students outside of regular school meals. FFVP began as a pilot program in 2002 and was converted into a nationwide program in the Food, Conservation, and Energy Act of 2008, also known as the 2008 Farm Bill. FFVP funds are allocated at a level of $50 to $75 per student per school year, or between $1 and $2 per week “to schools with the highest percentages of low-income students, to the maximum extent practicable.” Initial funding was $40 million for the 2008-2009 school year, rising to $65 million, $101 million, and $150 million in the following three school years, allowing more schools to participate in each year.

The 2008 Farm Bill also required the Secretary of Agriculture to conduct an evaluation of the program in order to determine “whether children experienced, as a result of participating in the program — (A) increased consumption of fruits and vegetables, (B) other dietary changes, such as decreased consumption of less nutritious foods; and (C) such other outcomes as are considered appropriate by the Secretary.”

The results presented in this interim report, for the 2010-2011 school year, focus on the total quantity of fruits and vegetables consumed and total energy intake (also referred to as total caloric intake), allowing the assessment of whether any additional fruit and vegetable consumption was in addition to, or in place of, other foods consumed.


This evaluation estimates the impact of FFVP using Regression Discontinuity (RD), which is considered the strongest possible design when random assignment is not feasible. The RD approach leverages the procedure by which schools are assigned to participate in FFVP. Specifically, the FFVP legislation and FNS guidance require that available FFVP funding be allocated to the poorest schools in each state that applied for the program, where poverty is defined by the percent of students eligible for free or reduced-price school lunch (FRPSL) in the previous school year.

The RD design estimates impacts by comparing schools immediately above and below the funding cutoffs in each of a nationally representative sample of states. The final preferred analytic sample included 4,696 students in 214 schools within 2.5 percentage points of the funding cutoff in each state: 2,225 students in 99 FFVP schools just above the funding cutoff, and 2,471 students in 115 non-FFVP schools just below the funding cutoff.

The study collected information on student food intake using diary-assisted 24-hour recall interviews. In FFVP schools, the diary was completed on a day on which FFVP fruits and/or vegetables were offered to students, allowing us to estimate the impact of FFVP on intake on FFVP days.


The results indicate that FFVP increased average fruit and vegetable consumption among students in participating schools on FFVP days by approximately one-quarter of a cup per day. This represents an increase of 15 percent over fruit and vegetable consumption levels in the absence of FFVP.

No increase in total energy intake was found. If an increase in total energy (caloric) intake had been found, we might have been concerned that FFVP could contribute to weight gain. Instead, increased fruit and vegetable consumption appears to have replaced consumption of other foods.


An increase in fruit and vegetable consumption of one-quarter of a cup per day is within the range observed in various other interventions to increase fruit and vegetable consumption in school children. Although there is no standard consensus as to what constitutes a meaningful change in fruit and vegetable intake, it is generally accepted that children with the lowest intakes are at greatest risk of poor health outcomes, and that the greatest benefit would be conferred by increasing intakes of fruits and vegetables among this group.

In this context, the fact that FFVP targets poorer schools is potentially significant. Because children in low socio-economic status households are more likely to have the lowest intakes of fruits and vegetables, increasing fruit and vegetable intakes in this population even by small amounts is likely to confer a health benefit.


Is An Exchange Effect Taking Place?

One can only be pleased that this research indicates that, at least under some circumstances, giving away free produce manages to boost produce consumption. One can only be disappointed that it only does so by a quarter cup per day on the day the free produce is distributed. This study doesn't go into cost/benefit analysis, but one suspects that it will be difficult to prove that a 1/4 cup increase in produce consumption on certain days really reduces health care costs sufficiently to justify the expenditure.

The study seems to have a significant flaw in its design. The key line is this:

The study collected information on student food intake using diary-assisted 24-hour recall interviews. In FFVP schools, the diary was completed on a day on which FFVP fruits and/or vegetables were offered to students, allowing us to estimate the impact of FFVP on intake on FFVP days.

The problem is, of course, that by limiting the study to days in which free fruits and vegetables are distributed, you open the possibility that what we are seeing is actually an exchange effect. Think of it this way: imagine that, mindful of your health, you decide to limit yourself to one Big Mac each week and, typically, you go to McDonald's on Wednesday to eat it. The other six days of the week, you go to McDonald's and eat a salad. Now imagine that McDonald's announces a promotion: Free Big Macs on Tuesday.

Quite probably you would switch your Big Mac Day to Tuesday from Wednesday to take advantage of the promotion. Now if McDonald's studies its Tuesday customers Ð "The day on which free Big Macs were offered” -- one will think it had a successful promotion, i.e., the promotion increased consumption of Big Macs because it would observe that the customers such as our prototypical one, customers who used to buy a salad on Tuesday, now buy Big Macs.

But that would be a deceptive interpretation of the success of the promotion. In fact, the promotion did not increase Big Mac consumption at all. It just switched dates of consumption.

With the USDA's study, by only looking at the actual date the free produce is distributed leaves open the possibility that the children's annual produce consumption did not change at all or, for that matter, even went down. 

We don't know a lot about produce consumption and its motivators. If we give children free apples on Wednesday, this might serve as a sampling tool and get the children excited about apples. They might, therefore, eat more apples than had they never been given the free apples. It is, however, also possible that children have a kind of natural set point for certain foods to avoid boredom. So if given their druthers, the children might enjoy oranges three times a week if given some in school, but they may not eat one on Sunday.

One reasonable supposition might be that the nature of the free produce distributed might have a real impact on the overall effect. If the produce distributed is, for example, composed of novel items the students have not tried before -- either new varieties of well known items such as apples or completely new items -- one might expect a greater long-term sampling effect. However, this might result in less short term consumption as some children will reject the novel items.

Quality would quite probably have an impact as well. We would love to see some research on how students perceive the quality of what they are given. If the apples purchased are nice and crisp, and the schools maintain proper refrigeration, the sampling effect may promote produce consumption. If the apples purchased are low quality and/or the schools don't maintain an optimal cold chain and the apples turn out to be mealy, the sampling effect may turn negative.

Another area we don't know much about is the impact of free food distribution in school on parental purchases. If you know that your child gets free apples every day, does that make a budget-stressed parent buy more apples or buy fewer? Indeed, especially if one thinks of produce purchases for children as being motivated by parents' desire to see their children eat healthy Ð might not the knowledge that the children are getting their "medicine” in school lead parents to shift spending to other foods? Maybe to other items in general? The thought might be the school is now providing the produce so we can spend the family budget on meat or shoes.

What about during school breaks? Does the distribution of free produce in school create fans for produce or does it create a mental association with a burdensome environment and lead children to want to avoid the product during summer vacation?

We just don't know. This is all speculation, but it is reasonable speculation and it is not addressed at all by this research. The key question, quite obviously, is not whether on the days we give away fresh produce does produce consumption increase. The key question is: If we follow a free produce distribution of X frequency in the schools, what is the impact on children's annual produce consumption?

This is a fairly obvious point, and the fact that the study was designed as it was makes one suspect that the bureaucrats chose a study design that would tend to support their initiative rather than give us valuable information on the impact of free distribution of produce on children's produce consumption.