Abstract
Research has consistently indicated that most children do not consume sufficient fruit and vegetables to provide them with a healthy, balanced diet. This study set out to trial a simple, low-cost behavioural nudge intervention to encourage children to select and consume more fruit and vegetables with their lunchtime meal in a primary school cafeteria. Methods: Four primary schools were randomly allocated to either the control or the intervention condition and baseline data were collected over two days in each school. Following this, changes were made to the choice architecture of the school cafeterias in the intervention schools and maintained over a three-week period. The intervention included improved positioning and serving of fruit, accompanied by attractive labelling of both fruit and vegetables on offer. Next, data were collected over two days in each school, with menus matched in each instance between baseline and follow-up. We employed a validated and sensitive photographic method to estimate individual children’s (N = 176) consumption of vegetables, fruit, vitamin C, fibre, total sugars, and their overall calorie intake. Results: Significant increases were recorded in the intervention schools for children’s consumption of fruit, vitamin C, and fibre. No significant changes were observed in the control condition. The increases in fruit consumption were recorded in a large proportion of individual children, irrespective of their baseline consumption levels. No changes in vegetable consumption were observed in either condition. Conclusions: These results are the first to show that modest improvements to the choice architecture of school catering, and inclusion of behavioural nudges, can significantly increase fruit consumption, rather than just selection, in primary-age children. This has implications for the development of national and international strategies to promote healthy eating in schools. Trial registration: AsPredicted: 3943 05/02/2017. URL: https://aspredicted.org/see_one.php?a_id=3943 Keywords: Choice architecture, Behavioural nudges, Fruit, Plant-based foods, Consumption, School lunch, Cafeteria, Healthy eating, Children
Generated Summary
This study presents a cluster randomized trial designed to evaluate the effectiveness of a low-cost behavioral nudge intervention aimed at increasing fruit and vegetable consumption among primary school children during lunchtime. The intervention was implemented in four primary schools in North Wales, with two schools serving as the control group and two receiving the intervention. The intervention involved changes to the school cafeteria’s choice architecture, including improved fruit positioning, attractive labeling, and the use of appealing names for fruits and vegetables. Data on children’s consumption of fruit, vegetables, vitamin C, fiber, total sugars, and overall calorie intake were collected using a validated digital photography method. The study aimed to assess whether these simple nudges could significantly increase fruit and vegetable consumption in a primary school cafeteria setting. The cluster-randomized design was utilized because the intervention was delivered at the school level rather than the individual level, which allowed the researchers to examine the effectiveness of the intervention in a real-world setting. This research approach, involving a controlled trial, aimed to rigorously evaluate the impact of the behavioral nudge intervention on children’s dietary behaviors.
Key Findings & Statistics
- The study included 176 children: 86 in the intervention group and 90 in the control group.
- The intervention schools showed a significant increase in fruit consumption (F (1, 86) = 17.21, p = .001), vitamin C (F (1, 86) = 11.39, p = .001), and fiber intake (F (1, 86) = 22.78, p = .001).
- No significant changes were observed in the intervention condition for vegetable consumption (F (1,86) = 0.52, p = .473) and sugar consumption (F (1, 86) = 3.52, p = .064).
- Significant increases in fruit consumption were found with a moderate effect size (r = .43).
- Median consumption of vegetables across measurement points and conditions varied from 22.45 to 29.73 g, with individual children consuming between 0 and 231 g of vegetables per day.
- The intervention group showed an increase in vitamin C consumption with a moderate effect size.
- In the control condition, fibre consumption decreased slightly, though significantly, with a small effect size.
- The calorie intake of the intervention group remained stable over time (Z = −.6, p = .548, r = −.06), whilst the calorie intake of the control group significantly decreased, with a small effect size, (Z = − 2.12, p = .034, r = −.21).
- Table 1 indicates that the estimate of fruit consumption (estimate of fixed effect) was -9.47, and the Wald Z score was -4.15 with a p-value of <.001.
- Table 2 Model estimates for the mixed effects analysis of the marginal means for the intervention conditions’ consumption dependent variables, which indicated the mean difference of fruit consumption was -9.47 (2.28) with a p-value of <.001.
- Table 3 highlights that there was a considerable difference in the number of children consuming various amounts of fruit with 63 of 86 children in the intervention group consuming no fruit at baseline versus 35 at follow up.
Other Important Findings
- The intervention involved five behavioral nudges: advertisements, attractive names, food labels, attractive servings, and serving order.
- The study found that the intervention was effective for fruit but not for vegetable consumption.
- The study measured individual children’s consumption using a digital photography method, which yielded fine-grained estimates of the weight of fruit and vegetables.
- The study highlights the potential for modest improvements in school catering environments, including behavioral nudges, to increase fruit consumption in primary-age children.
- The intervention’s success was most evident in those who previously consumed little to no fruit.
- The study noted that the intervention primarily targeted children’s fruit choices and consumption, due to space limitations on the fruit stand.
- The control group consumed significantly more fibre, vitamin C, and sugar than the intervention group.
Limitations Noted in the Document
- The study acknowledges that the effectiveness of certain nudges may vary.
- The study highlights that the catering staff’s encouragement of children’s fruit selection was not equal, but rather the intervention mostly targeted children’s fruit choices and consumption.
- The study points out that the intervention did not significantly affect vegetable consumption, possibly because the existing environment was already stimulating.
- The authors recommend that a close engagement with the catering teams is necessary to engender a sense of ownership, which promotes intervention fidelity.
- The study notes that the additional cost of fruit provision could present an obstacle to widespread implementation.
- The study suggests that the sustainability of the intervention may depend on addressing the increased demand for fruit.
- The study points out that in future interventions, acceptability of a variety of vegetables and fruit could possibly be increased by repeated tasting sessions organised by the school catering team.
Conclusion
The study’s findings underscore the potential of choice architecture interventions in school cafeterias to influence children’s dietary habits. The significant increase in fruit consumption, along with the parallel rise in vitamin C and fiber intake within the intervention schools, indicates the effectiveness of the employed behavioral nudges. The authors emphasize that these modest environmental alterations can lead to meaningful changes in children’s food consumption patterns. The positive results observed within the intervention schools, contrasted with the lack of change in the control schools, support the idea that targeted strategies can improve the fruit intake that is typical of children’s diets. The study indicates that taste preferences, environmental constraints, and catering practices may influence the effectiveness of these interventions. The authors note that engaging with the school catering staff to ensure that time and workload are managed in a reasonable way is paramount. A notable implication is that the intervention was most effective for those children who previously consumed little or no fruit. The study suggests that future interventions should consider strategies to enhance the appeal of vegetables, such as varied and repeated tasting sessions. Ultimately, the research provides valuable insights for policymakers, schools, and caterers regarding the implementation of simple, cost-effective strategies to promote healthier eating habits among children. The study’s results contribute to the growing body of knowledge supporting the use of behavioral economics to address public health challenges related to nutrition.