Decreasing consumption of sugar-sweetened beverages and Raising tap water consumption through Interventions based on Nutrition and sustainability for Kids: study protocol of the “DRINK” cluster randomised controlled trial

BACKGROUND: Effectiveness of actions to reduce sugar-sweetened beverage (SB) consumption in children still needs to be improved. Furthermore, the growing concern about sustainable food systems encourages to develop sustainability-based interventions. The objective of this cluster randomised controlled trial is to evaluate the long-term effectiveness of nutrition- and environmental sustainability-based interventions on the reduction in SB intake and on the increase in tap water consumption in 3rd to 6th grade primary school children (8 to 11 years of age). METHODS: Forty-eight French-speaking Belgian primary schools (equivalent to around 3500 pupils involved in the evaluation) are randomised using a factorial plan: (i) control, (ii) nutrition-based intervention, (iii) sustainability-based intervention, and (iv) both. The interventions (encouragement of water breaks; provision of posters, leaflets, reusable cups, and glass bottles; website; meetings at school) were undertaken from February 2022 to June 2023. Evaluation includes questionnaires for the children and their parents on various determinants of dietary behaviour, a 4-day diary to collect information on the child’s beverage consumption, and audits at schools. The first evaluation was conducted in Spring 2021 before any intervention, with the two post-intervention evaluations being held in 2022 and 2023. The main quantitative judgement criterion will be the change over time in the mean SB consumption (in ml/day) in the intervention groups compared with the control group. Given the context of the research (school), the safety of the intervention, and the content of data collection, a consent was acknowledged as unnecessary by the Ethical Committee of the Faculty of Psychology (ULB; n°073/2021), but children and parents are explicitly informed of their right to refuse to fill in the questionnaires. DISCUSSION: Multicomponent interventions based on nutrition and on environmental sustainability, alone or mixed, will provide an original and topical insight into health promotion at school around dietary behaviours. The dissemination plan will enable to widely inform stakeholders, school staff, and families, in addition to the scientific community through the usual medium (articles, conferences), about the research findings in 2024–2025. TRIAL REGISTRATION: ISRCTN Registry ISRCTN99843102. Retrospectively registered on 25 May 2021