A healthy diet is a crucial component for adolescents’ health and wellbeing. Current literature surrounding dietary intake and its effect on cognition, mental health and wellbeing has mainly focused on children, not adolescents. This review aims to synthesise findings from studies that explore the relationship between dietary intake and cognition, mental health and wellbeing in the adolescent population.

Electronic searches will date from 1 January 2000 to 7 October 2024 and will be conducted in CENTRAL, MEDLINE/PubMed, CINAHL via EBSCOHOST, ERIC, British Education Index, Child and Adolescent Studies, Education research complete, Psychology and Behavioural Sciences Collection, Social Policy and Practice Embase, and APAPsychINFO via OvidSP. Articles will be screened using defined inclusion and exclusion criteria and assessed for eligibility by five independent reviewers. Discrepancies will be reviewed by a third reviewer. The selection process of included articles will be reported by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram. A narrative summary will be used to report and synopsise the extracted data.

This systematic review does not require ethical approval. The dissemination strategy for this review comprises peer-reviewed publications, public health conference presentations and providing a valuable reference for healthy-food interventions in school and community-based settings as well as identifying gaps in the current literature and informing policy and practice.

CRD42025633083.

Food insecurity is increasing in the UK, impacting choice and diet quality. The current means-tested free school meals (FSM) policy was put in place to address dietary inequalities and food insecurity in school children. In secondary schools, approximately 20% of students who are eligible and registered do not take their FSM. Working across a range of schools that have variable levels of FSM uptake, this study aims to evaluate the effectiveness and cost-effectiveness of the current means-tested FSM policy in UK secondary schools on diet and food insecurity outcomes, understand what factors are associated with uptake and test the potential impact of any proposed policy change.

Secondary schools (n=32) in both Northern Ireland and the Midlands region of the UK are being recruited into the study. Data will be collected from school staff, governors, students and parents via questionnaires, as well as observational data of school eating environments. Qualitative data will be collected in selected case study schools (n=6–8). Multilevel modelling will be undertaken to evaluate the association between FSM uptake and fruit and vegetable intake, overall diet quality and food insecurity in all students. Economic evaluation will be conducted using a cost–utility approach. The effect of policy change will be modelled and school factors associated with FSM uptake explored using multiple methods.

Ethical approval has been obtained from Queen’s University Belfast Faculty of Medicine, Health and Life Sciences Research Ethical Committee (MHLS 23_55). Findings will be disseminated to key national and local agencies, to schools through reports and presentations, and to the public through media and open access publications.

School environments that encourage children to be physically active can embed lifelong positive health behaviours and contribute towards reducing health inequalities. The Health and Activity of Pupils in the Primary Years (HAPPY) study aims to: (1) explore the extent to which the WHO criteria for creating active school environments are implemented by primary schools and (2) examine associations between active school environments and children’s physical activity, mental health and educational performance.

The HAPPY study is a quasi-experimental study comprising: (1) a survey of state-funded Greater London primary schools to identify implementation of the WHO’s six criteria and (2) a cross-sectional study to examine associations between schools’ active environment score (derived from the school survey) and pupils’ physical activity, mental health and educational performance. For our cross-sectional study, we will recruit up to 1000 year-three children (aged 7–8 years). Our primary outcome is accelerometer (GENEActiv) assessed physical activity, our secondary outcomes are parent-reported child mental health (Strengths and Difficulties Questionnaire) and teacher-reported educational performance (age-related expectations). Using multilevel mixed-effects regression models, we will examine associations between the active environment score and physical activity. Physical activity will be included as a measure of acceleration and also different intensities (light, moderate, vigorous). We will repeat this analysis to examine associations between the active environment score and mental health and educational performance. We will adjust for school characteristics and area-level deprivation and include pupil characteristics (eg, sex, ethnic group) as covariates. Clustering at the school level will be included as a random effect.

Ethical approval has been obtained from Imperial College Research Ethics Committee (ref: 6800895). Findings will be disseminated through a summary report to all participating schools, peer-reviewed publications, presentations at national and international conferences and National Institute for Health and Care Research policy briefings.