Interventions for increasing fruit and vegetable consumption in children aged five years and under Edited (no change to conclusions)

Abstract

Abstract
Background

Insufficient consumption of fruits and vegetables in childhood increases the risk of future non‐communicable diseases, including cardiovascular disease. Testing the effects of interventions to increase consumption of fruit and vegetables, including those focused on specific child‐feeding strategies or broader multicomponent interventions targeting the home or childcare environment is required to assess the potential to reduce this disease burden.

Objectives

To assess the effectiveness, cost effectiveness and associated adverse events of interventions designed to increase the consumption of fruit, vegetables or both amongst children aged five years and under.

Search methods

We searched CENTRAL, MEDLINE, Embase and two clinical trials registries to identify eligible trials on 25 January 2020. We searched Proquest Dissertations and Theses in November 2019. We reviewed reference lists of included trials and handsearched three international nutrition journals. We contacted authors of included trials to identify further potentially relevant trials.

Selection criteria

We included randomised controlled trials, including cluster‐randomised controlled trials and cross‐over trials, of any intervention primarily targeting consumption of fruit, vegetables or both among children aged five years and under, and incorporating a dietary or biochemical assessment of fruit or vegetable consumption. Two review authors independently screened titles and abstracts of identified papers; a third review author resolved disagreements.

Data collection and analysis

Two review authors independently extracted data and assessed the risks of bias of included trials; a third review author resolved disagreements. Due to unexplained heterogeneity, we used random‐effects models in meta‐analyses for the primary review outcomes where we identified sufficient trials. We calculated standardised mean differences (SMDs) to account for the heterogeneity of fruit and vegetable consumption measures. We conducted assessments of risks of bias and evaluated the quality of evidence (GRADE approach) using Cochrane procedures.

Main results

We included 80 trials with 218 trial arms and 12,965 participants. Fifty trials examined the impact of child‐feeding practices (e.g. repeated food exposure) in increasing child vegetable intake. Fifteen trials examined the impact of parent nutrition education only in increasing child fruit and vegetable intake. Fourteen trials examined the impact of multicomponent interventions (e.g. parent nutrition education and preschool policy changes) in increasing child fruit and vegetable intake. Two trials examined the effect of a nutrition education intervention delivered to children in increasing child fruit and vegetable intake. One trial examined the impact of a child‐focused mindfulness intervention in increasing vegetable intake.

We judged 23 of the 80 included trials as free from high risks of bias across all domains. Performance, detection and attrition bias were the most common domains judged at high risk of bias for the remaining trials.

There is low‐quality evidence that child‐feeding practices versus no intervention may have a small positive effect on child vegetable consumption, equivalent to an increase of 5.30 grams as‐desired consumption of vegetables (SMD 0.50, 95% CI 0.29 to 0.71; 19 trials, 2140 participants; mean post‐intervention follow‐up = 8.3 weeks). Multicomponent interventions versus no intervention has a small effect on child consumption of fruit and vegetables (SMD 0.32, 95% CI 0.09 to 0.55; 9 trials, 2961 participants; moderate‐quality evidence; mean post‐intervention follow‐up = 5.4 weeks), equivalent to an increase of 0.34 cups of fruit and vegetables a day. It is uncertain whether there are any short‐term differences in child consumption of fruit and vegetables in meta‐analyses of trials examining parent nutrition education versus no intervention (SMD 0.13, 95% CI −0.02 to 0.28; 11 trials, 3050 participants; very low‐quality evidence; mean post‐intervention follow‐up = 13.2 weeks). We were unable to pool child nutrition education interventions in meta‐analysis; both trials reported a positive intervention effect on child consumption of fruit and vegetables (low‐quality evidence).

Very few trials reported long‐term effectiveness (6 trials), cost effectiveness (1 trial) or unintended adverse consequences of interventions (2 trials), limiting our ability to assess these outcomes. Trials reported receiving governmental or charitable funds, except for four trials reporting industry funding.

Authors' conclusions

Despite identifying 80 eligible trials of various intervention approaches, the evidence for how to increase children's fruit and vegetable consumption remains limited in terms of quality of evidence and magnitude of effect. Of the types of interventions identified, there was moderate‐quality evidence that multicomponent interventions probably lead to, and low‐quality evidence that child‐feeding practice may lead to, only small increases in fruit and vegetable consumption in children aged five years and under. It is uncertain whether parent nutrition education or child nutrition education interventions alone are effective in increasing fruit and vegetable consumption in children aged five years and under. Our confidence in effect estimates for all intervention approaches, with the exception of multicomponent interventions, is limited on the basis of the very low to low‐quality evidence. Long‐term follow‐up of at least 12 months is required and future research should adopt more rigorous methods to advance the field.

This is a living systematic review. Living systematic reviews offer a new approach to review updating, in which the review is continually updated, incorporating relevant new evidence as it becomes available. Please refer to the Cochrane Database of Systematic Reviews for the current status of this review.

Author(s)

Rebecca K Hodder, Kate M O'Brien, Flora Tzelepis, Rebecca J Wyse, Luke Wolfenden

Abstract

Plain language summary

 Interventions for increasing eating of fruit and vegetables in children aged five years and under 

 Background 

Not eating enough fruit and vegetables is a considerable health burden in developed countries. Eating adequate amounts of fruit and vegetables is associated with a reduced risk of future non‐communicable diseases (such as heart and circulatory disease). Early childhood represents a critical period for the establishment of dietary habits that track into adulthood. Interventions to increase consumption of fruit and vegetables in early childhood may therefore be an effective strategy to reduce this disease burden.

 Review question 

To assess the impact of interventions designed to increase eating of fruit or vegetables or both among children aged five years and under.

 Methods 

We searched various electronic databases and relevant journals to find trials. We contacted authors of included trials for additional potentially relevant trials. Any randomised trial (participants have the same chance of being assigned to treatment or control) of interventions aiming to increase the intake of fruit or vegetables or both by children aged five years and under that measured intake was eligible. Two review authors independently searched for and extracted information from trials. The evidence is current to January 2020.

 Results 

We included 80 trials with 12,965 people taking part. Fifty trials examined child‐feeding practice interventions (e.g. repeated exposure to vegetables), 15 examined parent nutrition education interventions, 14 examined multicomponent interventions (e.g. combining preschool policy changes with parent education), two examined child nutrition education interventions and one examined a child‐focused mindfulness intervention. Child‐feeding practice interventions may lead to, and multicomponent interventions probably lead to, small increases in children's intake of fruit and vegetables in the short term (less than 12 months). It is uncertain whether parent or child nutrition education interventions alone are effective in increasing children's eating of fruit and vegetables. There was not enough information to assess long‐term effectiveness, cost effectiveness or unintended harms. Trials reporting funding support received governmental or charitable funds, except for four trials that received industry funding.

 Conclusions 

Child‐feeding practices may increase fruit and vegetable intake by children (by 5.30 grams a day), but this conclusion is based on low‐quality evidence and our confidence in this effect is limited. Multicomponent interventions probably increase fruit and vegetable intake by children (by 0.34 cups a day), based on moderate‐quality evidence. It is uncertain whether parent nutrition education interventions increase children's fruit and vegetable intake.

This is a living systematic review. Living systematic reviews offer a new approach to review updating, in which the review is continually updated, incorporating relevant new evidence as it becomes available. Please refer to the Cochrane Database of Systematic Reviews for the current status of this review.

Author(s)

Rebecca K Hodder, Kate M O'Brien, Flora Tzelepis, Rebecca J Wyse, Luke Wolfenden

Reviewer's Conclusions

Authors' conclusions

Implications for practice

We found little evidence of effect for interventions to increase the fruit and vegetable consumption of children aged five years and under, to provide direction for health policy‐makers and practitioners. The effect of parent nutrition education is uncertain. Low‐quality evidence for specific child‐feeding interventions (such as repeated exposure and rewards) suggests such interventions may be effective, but such findings should be interpreted with caution, given that no data were reported for important outcomes such as costs and unintended consequences of such interventions. We found moderate‐quality evidence for multicomponent interventions, suggesting that such interventions are probably effective, and therefore could be considered a priority approach for implementation by practitioners and policy‐makers. The multicomponent interventions that reported positive effects on fruit and vegetable consumption were largely those that focused exclusively on fruit and vegetable consumption (rather than nutrition generally), involved parents in some component of the intervention and included nutrition education. However, similar to child‐feeding interventions no data were reported for important outcomes such as costs and unintended consequences for multicomponent interventions, which are important factors when considering implementation. Additionally, the effect sizes for both child‐feeding and multicomponent interventions were small (equivalent to an increase in as‐desired vegetable intake of 5.30 g and 0.34 cups of fruit and vegetables consumed a day respectively), which may limit the potential public health benefits of implementing these types of interventions.

Implications for research

Despite the large number of trials, the lack of high‐quality research in this area demonstrates the continuing considerable scope for policy‐makers, researchers and practitioners to develop and evaluate the impact of a variety of initiatives to improve fruit and vegetable intake in children aged five years and under. Behavioural interventions delivered by health professionals, telephone‐ or computer‐based programmes, interventions delivered through preschools, play‐groups, sports clubs, or co‐operatives, and those that address access issues through subsidies or other incentives all have merit, and rigorous evaluation of such interventions for children aged five years. Importantly, testing the effectiveness of these interventions under more pragmatic conditions may provide evidence of their potential real‐world impact, particularly when implemented at scale (McCrabb 2019; Wolfenden 2020). Additionally, trials should seek to test interventions that are based on logic models of change, appropriate theoretical frameworks and evidence, and build on existing knowledge to optimise the potential impact (Wolfenden 2019b). As the aetiology of child diet is complex, interventions that target multiple determinants across a number of settings may be most likely to be effective. Additionally, future trials should rigorously assess and report the cost effectiveness and adverse effects of any tested intervention approaches to ensure that essential evidence is generated for, and accessible to, clinicians and policy‐makers to aid decision‐making about selection of interventions focused on child fruit and vegetable consumption that are most likely to be of benefit.

This review identified a number of opportunities for future or continued intervention research targeting the fruit and vegetable consumption of children aged five years and under, including:

  • the exploration and development of intervention strategies that can achieve larger effect sizes;
  • the investigation of potential adverse effects of interventions (e.g. increased family grocery costs, or adverse effects on parental self‐esteem or sense of competence) as a routine part of intervention trials;
  • examination of the cost effectiveness of interventions found to be effective;
  • interventions with extended periods of follow‐up to assess sustainability of intervention effects;
  • interventions delivered using electronic modalities such as the Internet or mobile phones;
  • interventions implemented across a broader range of settings, including health services and sports clubs;
  • the investigation of the impact of interventions for children from low‐income, minority or indigenous communities (including by subgroup analyses).

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