PROTOCOL Open Access Early childhood education and care-based healthy eating interventions for improving child diet: a systematic review protocol Jacklyn Jackson 1,2,3,4* , Luke Wolfenden 1,2,3,4 , Alice Grady 1,2,3,4 , Melanie Lum 1,2,3,4 , Alecia Leonard 1,2,3,4 , Sam McCrabb 2 , Alix Hall 2,3,4 , Nicole Pearson 1,2,3,4 , Courtney Barnes 1,2,3,4 and Sze Lin Yoong 1,2,3,4 Abstract Introduction: Diet during infancy and early childhood can have implications on child growth, health, and developmental trajectories. Yet, poor dietary habits are common in young children, who often consume diets that are not aligned with dietary recommendations. Early childhood education and care (ECEC) is a recommended setting to deliver healthy eating interventions as they offer existing infrastructure and access to a large number of children. This protocol aims to describe the methods of a systematic review to assess the effectiveness of healthy eating interventions conducted within the ECEC setting to improve child diet. Methods and analysis: Eight electronic databases including Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, EMBASE, CINAHL Complete, PsycINFO, ERIC, SCOPUS, and SPORTDiscus will be searched from conception to March 2020. Randomised controlled trials (RCT) of dietary interventions targeting children aged up to 6 years conducted within the ECEC setting (including pre-schools, kindergartens, long day care, and family day care) will be included in the review. The primary review outcome is any measure of child dietary intake. Secondary outcomes include (i) child anthropometrics, (ii) child cognition, (iii) child mental health, (iv) child quality of life, (v) the absolute cost or cost-effectiveness of included interventions, and (vi) any reported adverse effects. Study inclusion, data extraction, and risk of bias assessments will be performed independently by two reviewers. Meta-analyses will be performed if adequate data is available, else review findings will be described narratively. Discussion: This systematic review seeks to synthesise the effectiveness of healthy eating interventions conducted within the ECEC setting for improving child diet. This review will also seek to describe the effect of ECEC-based healthy eating interventions on a variety of important secondary outcomes (adverse events and cost-effectiveness) that will enhance the public health policy and practice relevance of review findings. Systematic review registration: PROSPERO [ID CRD42020153188] Keywords: Early childhood education and care, Child diet, Healthy eating, Systematic review protocol © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. * Correspondence: Jacklyn.Jackson@health.nsw.gov.au 1 Hunter New England Population Health, Wallsend, New South Wales 2287, Australia 2 School of Medicine and Public Health, University of Newcastle, Callaghan, New South Wales 2308, Australia Full list of author information is available at the end of the article Jackson et al. Systematic Reviews (2020) 9:181 https://doi.org/10.1186/s13643-020-01440-4