N° 90 | June 2014

Why are fruit and vegetable initiatives in schools effective (and why are they sometimes not)?

Vegetables can be a hard sell

“My kids just don't like vegetables.” How many times have you heard that!

Anyone who has ever been around infants and young children will know vegetables are a tougher sell than many other foods. They get thrown on the floor. They get pushed to the side of the plate. They get left to the end of the meal. Many fruits can be a tough sell too. It’s hardly surprising that people in most countries around the world are still not eating enough vegetables and fruits for optimum health.

Parents shouldn’t feel guilty though, or be unduly harsh on the children, because it’s routed in science. Biologically it is easier to like sweet, energy-dense foods.

Effective programmes

This is always going to make vegetables and fruits – especially vegetables – a harder sell for children. At the same time, it is known that actions to promote fruit and vegetable consumption can work. Take the evidence from studies of school-based programmes.

Systematic reviews of the evidence show these can be effective1-4. National school fruit and vegetable programmes show positive results; 18 of 21 EU Member States that reported on the results on the EU School Fruit Scheme reported positive impacts on consumption5; so did the evaluation of the Fresh Fruit and Vegetable Programme in the United States6.

Overcoming barriers to access

So given that fruits and vegetables can be a hard sell, why do these programmes work? A leading reason is that they overcome barriers to access for kids actually like fruits and vegetables but who don’t get enough at home. Increases of intake are often higher among children who initially eat less, suggesting that the programmes are removing a constraint to access5-7. Evidence from free schemes also suggests they enhance access. The free scheme that was in place in Norway until recently was used by all socioeconomic groups – effectively reducing inequalities in intake. In contrast, the subsidised scheme also in place was used mainly by children of higher socioeconomic status who already consume a lot of fruits and vegetables, and therefore had little impact on access8.

An opportunity for healthy preference learing

A second leading reason that they can help fruit and vegetable programmes work is that children to learn to like fruits and vegetables. There is strong evidence that when children are repeatedly exposed to tasty vegetables and fruits, their liking increases, and this then leads to greater consumption at the time and later in life9. By exposing kids to fruits and vegetables and providing the opportunity for repeat tasting opportunities, these programmes can have the effect of increasing preferences for fruits and vegetables.

This is clearly shown by evaluations of programmes which measure preferences as an outcome: before the programmes, kids say they don’t like the produce; afterwards they say they do10. The Food Dudes programme is explicitly based on the science of preference formation and uses exposure combined with modelling and rewards to effectively boost consumption11. This is good news because it means children take their preferences home with them and don’t eat less at other times of day. Indeed, many studies show positive impacts on total daily intake3.

The need for sustained action

The picture isn’t entirely rosy, however. The effects are relatively modest – the most recent metaanalysis showed an effect of 0.32 portions per day for children aged 5-123. However, this would be expected when the main challenge is low preferences at baseline since preferences take time to form and change. As shown by an intervention in the Netherlands, programmes which provide opportunities for repeated exposure are more likely to be effective over the longer term12. Therefore it seems that to have a sustained effect, initiatives need to run over several years2.

Modest impacts could also be expected when initiatives act to overcome barriers to access. This is because of problems beyond the school gate. For example, a study of First Nation Canadians showed that a multi-component fruit and vegetable programme signifi cantly improved preferences for vegetables and fruit in the participating students yet did not improve self-effi cacy to consume13. This finding was attributed in part to community-level barriers to healthy eating.

Heterogeneity of effects

Along with modest outcomes, there is also a lot of variability. While many programmes work, some do not. In addition, some elements appear effective in some circumstances but ineffective in others. For example, evaluation of the Northern Fruit and Vegetable Pilot Programme in Canada found no evidence that including education in a free scheme boosted effectiveness10. Yet in other cases, educational programmes have been found to be effective in changing preferences14.

Multi-component approaches

The evidence indicates that the effects of fruit and vegetable initiatives depends on whether they are adequately tailored to the target population. For example, initiaves that create access won't make any difference for children who already eat enough at home; repeat exposure won’t make any difference to children who already like them; education won't work if the kids don’t like the produce. This likely explains why “multicomponent” approaches have, on balance, proved more effective – because they capture the variations within and between children in individual schools2,4.

Programmes to promote fruit and vegetable intake in schools are much more likely to work when they are based on an understanding of the mechanisms through which they can have an effect, such as creating access and/or preference learning. Paying greater attention to the characteristics of young children in schools could go a long way in helping design more effective policies and programmes to boost fruit and vegetable consumption.

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