N° 57 | June 2011

The effects of a fruit and vegetable program on unhealthy snacks during mid-morning school breaks Results of the Dutch Schoolgruiten Project

In the Netherlands, the Schoolgruiten (a Dutch acronym for ‘school fruits and vegetables’) Project was developed to promote fruit and vegetable (F&V) intake among primary schoolchildren1,2. The main strategies within this project targeted availability, accessibility and exposure of F&V at school through a F&V scheme. The children in the intervention group received a piece of fruit or ready-to-eat vegetables for free twice a week.

The health enhancing effects of increased F&V intake would, however, be even more apparent if the increased F&V intake additionally led to a lower intake of unhealthy, high calorie snacks. Interventions that shift choice from high calorie snacks to healthier lower calorie snacks (i.e. F&V) can reduce caloric intake, thereby enhancing the efficacy of obesity prevention and treatment. However, little is known about whether interventions aimed at increasing F&V intake result in a lower intake of unhealthy snacks.

Therefore, the aim of this study was to investigate if the Dutch Schoolgruiten Project could additionally reduce the intake of unhealthy, high calorie snacks during mid-morning school breaks.

Children and parents were both involved in this study. The study applied a longitudinal design with a baseline and two follow-up measurements (one year and two years later). Separate questionnaires for children and their parents were developed, both based on the validated Pro Children questionnaires3. Participating children (mean age 9.9 years at baseline) and their parents completed the questionnaires at all three measurements, allowing data analyses based on child as well as parentreports. The amounts of F&V and unhealthy snacks for consumption at school during the mid-morning break were measured using a single item question included in these questionnaires. Finally, 771 children and 435 parents were included for this study. Multilevel autoregressive logistic regression models with a three-level structure (school, child and time) were used to assess the effect of the intervention on both F&V and unhealthy snack consumption.

Children of the intervention group brought more often F&V and fewer unhealthy snacks from home to school than the children of the control schools.

Most children brought no F&V or unhealthy snacks from home to school to be consumed during the mid-morning break. The percentage of children in the intervention group that brought F&V from home to school was somewhat higher than the percentage in the control group for all three measurements.

Based on the child-reported data, no significant associations were observed between the number of F&V and the number of unhealthy snacks brought from home to school for the three measurement times (baseline X2=0.084; p=0.772, first follow-up X2=0.028; p=0.867, second follow-up X2=1.333; p=0.248).

According to child-reported data, the children of the intervention group brought F&V from home to school at follow-up significantly more often than the children of the control schools (OR=1.41, 95% CI=1.04–1.90). The results of the parent-reported data supported this observation (OR=1.58, 95% CI=1.10–2.28). Adjusting for the amount of unhealthy snacks brought from home did not influence the results. According to child-reported data, the children of the intervention schools brought fewer unhealthy snacks from home to be eaten in the mid-morning break at follow-up (OR=0.56, 95% CI=0.34 ̶0.92), which was also unaffected by the adjustment for the number of F&V snacks brought from home.

The Schoolgruiten intervention is an effective way to increasing F&V consumption and decreasing consumption of unhealthy snacks in the mid-morning break among primary schoolchildren.

The results of this study indicated that children in the intervention group more often brought F&V and less often brought unhealthy snacks from home to school. Based on the parents’ reports, only significant positive effects were found on the amount of F&V brought from home, and no effect on the number of unhealthy snacks. This might be partly because of power issues since parent-report data were available for fewer children. It is often assumed that increasing F&V intake would almost automatically result in a decrease in the intake of other foods, such as unhealthy snacks. Few studies, however, have actually assessed whether this is the case, and this lack of compensation could lead to a higher calorie intake and contribute further to unnecessary weight gain. No significant associations were found between the amount of F&V and the number of unhealthy snacks, and the results showed that no effects on the number of snacks brought from home could be explained by the amount of F&V and vice versa. This might indicate that F&V and unhealthy snack consumption are not strongly associated, nevertheless increasing F&V was moderately associated with a decrease in the unhealthy snacks.

The behaviour choice theory4 might help explain the results of this study. This theory is designed to understand how people allocate choices among alternatives. People can choose an alternative for a preferred product when the availability of this product is constrained. In this intervention, it might have been that access to snacks was constrained because parents were influenced by the subscription program and provided fewer unhealthy snacks to be consumed during the mid-morning break. Another solution to restricting access to unhealthy snacks might be school policy. This suggests that (primary) schools should introduce a restrictive snack policy as part of a multi-faceted approach to improve children's diet quality.

Despite the fact that the intervention was not primarily developed to decrease the amount of unhealthy snacks, this study provides some evidence that the Schoolgruiten intervention was effective in increasing F&V consumption and decreasing consumption of unhealthy snacks during the mid-morning break. It further indicates that restricted access to unhealthy snacks can play an important role in reducing snack intake during school breaks.

Based on: Tak et al. J Hum Nutr Diet. 2010 23(6): 609-615

  1. Tak N.I., te Velde S.J. & Brug J. Public Health Nutr. 2007; 10: 1497-1507.
  2. Tak N.I., te Velde S.J. & Brug J. Public Health Nutr. 2009; 12: 1213-1223. Epub 2008 Oct 22.
  3. Haraldsdottir J. Ann Nutr Metab 2005; 49: 221-227.
  4. Goldfield G.S. & Epstein L.H. Health Psychology. 2002; 21: 299-303.
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