Ahern 2019.

Study characteristics
Methods	Study design C‐RCT Funding "Research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under the grant agreement no. 245012‐HabEat; coordinated by Dr Sylvie Issanchou.”
Participants	Description Children aged 24 to 60 months attending 5 nurseries located in the West and South Yorkshire areas, UK N (randomised) 5 nurseries, 184 children Age Child (mean): repeated exposure = 45.6 months, variety = 40.0 months Parent: not reported % female Child: repeated exposure = 45%, variety = 43% Parent: not reported SES and ethnicity “All five nurseries served areas located within the 50% most deprived (small areas) in England according to the Index of Multiple Deprivation scores [https://www.gov.uk/government/collections/english‐indices‐ofdeprivation].” “Children attending two of the nurseries were predominantly White British, while children at the remaining three were predominantly South Asian.”Inclusion/exclusion criteria No explicit inclusion/exclusion criteria stated for this trial, however, children were screened for food allergies (as reported by parents). Recruitment “Parents of pre‐school children aged 24‐60 months were recruited through local day care nurseries in the West and South Yorkshire areas, UK.” Recruitment rate Child: not reported Nursery: 50% (5/10) Region West and South Yorkshire areas (UK)
Interventions	Number of experimental conditions 2 Number of participants (analysed) 40 children (not reported by group) Description of intervention 3 target vegetables were selected for the intervention that were familiar but were not typically eaten as snacks: baby sweet corn, celery, and red pepper. “The target vegetables were offered as the single snacks (in the RE condition) and included in the mixed vegetable snack (in the V condition). To ensure variety, a further 2 vegetables, radish and green pepper, were also selected to be included in the mixed vegetable snack based on the same criteria (familiar, but were not typically consumed as snacks).” “The single vegetable snack consisted of 100 g of one of the three target vegetables (baby sweet corn, celery or red pepper). The variety snack was a mix of 20 g of each of the five vegetables (baby sweet corn, celery, red pepper, green pepper and radish).” Duration 3 weeks Number of contacts 6 exposures (twice/week) Setting Preschool Modality Face‐to‐face Interventionist Nursery staff (researcher present for first session) Integrity “In total, 115 children received at least 5 of the 6 exposures and were present for all pre‐intervention and post‐intervention measures.” Date of study Not reported Description of control N/A
Outcomes	Outcome relating to children's fruit and vegetable consumption Child’s consumption of vegetable snacks (grams). Unclear how vegetable snacks weighed and recorded Outcome relating to absolute costs/cost‐effectiveness of interventions Not reported Outcome relating to reported adverse events Not reported Length of follow‐up from baseline 5 and 10 weeks Length of follow‐up postintervention < 1 (2 to 5 days) and 5 weeks Subgroup analyses “In order to identify differences in the age, BMI and gender of the two groups a one way analysis of variance and also chi‐square tests were conducted.” “No main effects or interactions involving age or BMI z‐scores were found.” Loss to follow‐up (at < 1 week and 5 weeks) Overall = 48%, 78% Analysis Adjusted for clustering Sample size calculation was performed
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: “Nursery classes were randomly assigned to a condition (RE or V) and then randomly assigned to a target vegetable (baby corn, red pepper, or celery) using a block approach.” No further information
Allocation concealment (selection bias)	Unclear risk	No information provided re concealment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Outcome group: intake (grams) – no blinding but objective measure of child’s vegetable intake and unlikely to be influenced by performance bias
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome group: all/objective measure – unlikely personnel influence intake however unclear if the researcher or nursery staff completed the measurements
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow‐up: 69/184 = 38% Same reason, did not receive at least 5 exposures, no ITT reported Not provided by group
Selective reporting (reporting bias)	Unclear risk	Unclear – no protocol or trial registration
Other bias	Unclear risk	Recruitment bias (low risk): randomised after recruitment Baseline imbalance (unclear risk): to control for significant differences in age and BMI z‐scores, analyses included these factors as covariates. Age was first recalculated to be mean centred. Loss of clusters (low risk): no evidence of loss of clusters Incorrect analysis (low risk): adjusted for clustering. “In order to investigate whether the nursery conditions produced any clustering, the intra cluster correlation for the pre intervention intake was assessed by calculating a mixed model using lmer in R with only nursery as a random factor. This produced an ICC of 0.04, VIF=1.72. In order to ensure this did not impact the result, all the main analyses were recalculated using multilevel models with nursery and child as random factors. This produced no change in the pattern of results reported, and for simplicity the simpler ANCOVA results are reported here.” Contamination bias (low risk): no contamination bias evident.