Efficacy of repeated exposure and flavour–flavour learning as mechanisms to increase preschooler's vegetable intake and acceptance

Abstract

Dutch children's diets, like the diets of many children in Europe and the US are not balanced, do not contain enough vegetables and have been associated with a high prevalence of childhood obesity. Promoting children's vegetable intake is challenging. We investigated the relative effectiveness of repeated exposure and flavour-flavour learning in increasing vegetable intake and acceptance in preschoolers. During an intervention period of 7 weeks, 39 toddlers (aged 1.5 to 4 years) consumed red beet and parsnip crisps at day-care centres in Wageningen, the Netherlands. Half of the group received red beet crisps with a dip of tomato ketchup (Conditioned [C]) and parsnip with a neutral white sauce (Unconditioned, [UC]), whereas for the other half the order was reversed (red beet [UC], parsnip [C]). Preference and ad libitum consumption of vegetable crisps were measured once before and three times after the intervention over the course of a 6-month follow-up period to assess longer-term effects. Intake increased significantly after the intervention for both vegetables (on average with 8 g; an increase of approximately 300%), and this effect was persistent even 6 months afterwards. The increase was irrespective of crisps being offered with C or UC dip sauce. These results suggest a robust and persistent effect of repeated exposure but no effect of flavour-flavour learning. Offering pure vegetable tastes repeatedly is sufficient to increase intake.