Optimising Repeated Exposure: Determining Optimal Stimulus Shape for Introducing a Novel Vegetable among Children

Although it is well evident that a healthy diet rich in fruit and vegetables could prevent a number of major chronic diseases, national and international guidelines concerning their intake are not being reached by a large percentage of the population, including children. Thus, it is of interest to investigate how the consumption of this food group by children could be increased. The aim of this study was to examine the impact of serving style on the consumption of a raw snack vegetable (daikon) and the influence of its exposure on liking and intake of the vegetable. A group of 185 children 3-5 years old participated in the study. Two kindergartens served as intervention groups, while the third was assigned to be the control group of the study (n = 50). The intervention groups were repeatedly exposed to one of three different serving styles of daikon: sticks (n = 42), triangles (n = 46) or grated (n = 47), and they were all visited 7 times during the exposure period, on the same frequency (twice per week). Familiarity and liking of the target vegetable, daikon, and six other vegetables (cucumber, celery, celeriac, broccoli, cauliflower and beetroot) were measured at baseline, post-intervention and two follow up sessions (3- and 6-month) to investigate the likelihood of generalisation effects. Intake of daikon was measured at all control sessions and exposures. Moreover, children were asked to rank their favourite serving style of daikon and beetroot, among triangle, stick and grated, towards understanding the influence of shape on the efficacy of the exposure. The results revealed significant changes between liking and intake of daikon for the groups of triangles and sticks and the control group (p < 0.05). The group that received grated daikon did not show significant differences in liking and at intake levels during the exposures but performed well in the long-term. Throughout the exposure period, intake levels followed an overall increasing pattern, with all the groups to demonstrate a decrease of their intake at the last session, which was not found significant for the triangle group. Mere exposure was efficient towards increasing liking and intake of the novel vegetable with all the shapes to deliver positive results, but based on this study no particular serving style can be recommended.