Application of the multiphase optimisation strategy to develop, optimise and evaluate the effectiveness of a multicomponent initiative package to increase 2-to-5-year-old children's vegetable intake in long day care centres: a study protocol

Introduction Globally, children do not eat enough core foods, with vegetable intakes persistently low. Early life is critical for establishing vegetable acceptance and intake. Increased usage of formal childcare has led to the importance of childcare settings shaping children's food intake. This study will use the multiphase optimisation strategy to develop, optimise and evaluate the effectiveness of a multicomponent initiative package to increase 2-to-5-year-old children's vegetable intake in long day care centres. Methods and analysis The preparation phase will use existing literature and best practice guidelines to develop three initiatives aiming to: (1) increase vegetable provision at mealtimes, (2) deliver a vegetable-focused sensory curriculum and (3) use supportive mealtime practices encouraging children's tasting of vegetables. The optimisation phase (N=32 centres) will use a 12-week, eight-condition factorial experiment to test main and synergistic effects of the initiatives. The optimum combination of initiatives producing the largest increase in vegetable intake will be identified. The evaluation phase (N=20 centres) will test the effectiveness of the optimised package using a 12-week waitlist randomised controlled trial. Primary outcomes are children's vegetable intake and food group intake at long day care. Secondary outcomes are menu guideline compliance, cook and educator knowledge and skills, and reach. Process evaluation will include fidelity, acceptability, barriers and facilitators, and compatibility with practice. Repeated measures ANOVA with interaction effects (optimisation phase) and linear mixed modelling (evaluation phase) will test effects of the initiatives on vegetable intake. Ethics and dissemination This study has received ethics approval from the Flinders University Research Ethics Committee (Project No: 1873) for the optimisation phase. Approval for the evaluation phase will be obtained following completion of optimisation phase. Findings will be disseminated to stakeholders, including long day care centres and childcare organisations; and to researchers via peer-reviewed journals and conferences. Trial registration numbers ACTRN12620001301954, ACTRN12620001323910p.