Do techniques that increase fruit intake also increase vegetable intake? Evidence from a comparison of two implementation intention interventions

Interventions to increase fruit and vegetable intake typically apply manipulations that do not distinguish fruits and vegetables as separate food groups. This study aimed to compare the efficacy of separate implementation intention instructions with a combined implementation intention instruction on separate indices of fruit and vegetable intake, and investigate the written content of implementation intentions for behavioural strategies focusing on the ‘target’ action of consumption or the ‘preparatory’ actions that enable consumption. Participants (N = 580) were randomised to one of three conditions (control; separate implementation intentions; combined implementation intention). The findings were: (a) the combined instruction was successful in increasing fruit intake but not vegetable intake, whereas the separate instructions generated a significant increase in both fruit intake and vegetable intake, and (b) ‘target’ strategies appear more beneficial for increasing fruit intake where as preparatory strategies show some promise for vegetable intake. The conceptual and practical implications of this work are discussed in relation to future research into increasing fruit and vegetable consumption.

► We looked at how implementation intentions can change fruit and vegetable intake.
► Content analysis showed that strategies used to change fruit and vegetables differ.
► Participants showed preference for increasing fruit rather than vegetable intake.
► Vegetable intake may be more difficult to change than fruit intake.
► Fruit and vegetables should be treated as separate food groups.