Repeated exposure more effective than flavour flavour learning as mechanism to increase vegetable consumption in pre-school children

Children’s habitual diets contain too much high-energy-dense food like lipids and carbohydrates, but little low-energy foods like vegetables. Promoting vegetable intake in children serves better nutritional standards and energy balance. However, since most children dislike vegetables, increasing their intake is a challenge. We investigated the relative effectiveness of repeated exposure (RE) and Flavour-Flavour-Learning (FFL) in increasing vegetable intake and acceptance in pre-schoolers ( n  = 39). During an intervention period of seven weeks, toddlers consumed vegetable crisps (freeze-dried red beet and parsnip) twice per week. Half of the group received red beet crisps with a dip of tomato-ketchup (C+), and parsnip with a neutral white-sauce (C−), whereas for the other half the order was reversed (red beet C−, parsnip C+). Outcome measures were preference and ad libitum consumption of both crisp flavours (without dip-sauces), measured before, shortly after the intervention, and two and six months following conditioning to assess longer-term effects. Intake increased significantly after the intervention for both vegetables (on average with 8g; an increase of approx. 300%), and this effect was persistent even six months afterwards. The increase was irrespective of crisps being offered with C+ or C− dip sauce. No changes in initial preference for either red beet or parsnip were found. This suggests a robust and persistent effect of RE but no effect of FFL. In conclusion, simply offering pure vegetable tastes repeatedly is sufficient to increase intake over time, rather than adding flavour to the food.