Evaluation of the impact of a school gardening intervention on children’s fruit and vegetable intake: a randomised controlled trial

Abstract

BackgroundCurrent academic literature suggests that school gardening programmes can provide an interactive environment with the potential to change children’s fruit and vegetable intake. This is the first cluster randomised controlled trial (RCT) designed to evaluate whether a school gardening programme can have an effect on children’s fruit and vegetable intake.MethodsThe trial included children from 23 schools; these schools were randomised into two groups, one to receive the Royal Horticultural Society (RHS)-led intervention and the other to receive the less involved Teacher-led intervention. A 24-hour food diary (CADET) was used to collect baseline and follow-up dietary intake 18 months apart. Questionnaires were also administered to evaluate the intervention implementation.ResultsA total of 641 children completed the trial with a mean age of 8.1 years (95% CI: 8.0, 8.4). The unadjusted results from multilevel regression analysis revealed that for combined daily fruit and vegetable intake the Teacher-led group had a higher daily mean change of 8 g (95% CI: −19, 36) compared to the RHS-led group -32 g (95% CI: −60, −3). However, after adjusting for possible confounders this difference was not significant (intervention effect: −40 g, 95% CI: −88, 1; p = 0.06). The adjusted analysis of process measures identified that if schools improved their gardening score by 3 levels (a measure of school gardening involvement - the scale has 6 levels from 0 ‘no garden’ to 5 ‘community involvement’), irrespective of group allocation, children had, on average, a daily increase of 81 g of fruit and vegetable intake (95% CI: 0, 163; p = 0.05) compared to schools that had no change in gardening score.ConclusionsThis study is the first cluster randomised controlled trial designed to evaluate a school gardening intervention. The results have found very little evidence to support the claims that school gardening alone can improve children’s daily fruit and vegetable intake. However, when a gardening intervention is implemented at a high level within the school it may improve children’s daily fruit and vegetable intake by a portion. Improving children’s fruit and vegetable intake remains a challenging task.Trial registrationISRCTN11396528Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-014-0099-7) contains supplementary material, which is available to authorized users.

Evaluation of the impact of school gardening interventions on children's knowledge of and attitudes towards fruit and vegetables. A cluster randomised controlled trial

“…In the primary outcome analysis the RHS-led intervention was not associated with an increase in FV intake compared to the teacher-led intervention (Christian et al, 2014a). Many interventions do not appear to have lasting impact and improvement in behaviour only lasts as long as the intervention itself .…”

“…In the primary outcome analysis the RHS-led intervention was not associated with an increase in FV intake compared to the teacher-led intervention (Christian, Evans, Nykjaer, Hancock, & Cade, 2014a). For this current analysis of secondary outcomes we hypothesized that children who took part in the RHS-led gardening intervention, nevertheless, would show greater knowledge and positive attitudes towards FV than those in the teacher-led gardening intervention.…”

“…In the teacher-led intervention one school withdrew and all data were lost in transit for another school ( figure 1 shows the CONSORT flowchart for this current analysis of secondary outcomes). Further details of the trial and primary outcome analysis are described elsewhere Christian et al, 2014a). Ethical approval was obtained through the Leeds Institute of Health Sciences and Leeds Institute of Genetics, Health and Therapeutic joint ethics committee (reference 09/012).…”

“…The diaries were the Child and Diet Evaluation Tool (CADET) which has been validated in 8-11 year olds with an emphasis on fruit and vegetable intake (Christian et al, 2014b). Power calculations for the trial based on FV intake, the primary outcome, were previously described, along with additional information Christian et al, 2014a).…”

“…This was evaluated using a child questionnaire which included questions on personal and environmental factors, such as attitude, self-efficacy, perceived barriers and encouragement at home, as well as knowledge of fruit and vegetables, which could potentially mediate increased FV consumption. This cluster randomised control trial is the first UK trial to evaluate school gardening schemes and consists of a large sample of year 3 and 4 pupils aged 7 to 10 years from London primary schools (Christian, Evans, Conner, Ransley, & Cade, 2012;Christian et al, 2014a;Royal Horticultural Society, 2010).…”