Abstract
INTRODUCTION: Adolescents in informal urban communities, defined as settlements that fall outside of formal governmental planning and regulatory frameworks, are at increasing risk of poor-quality diets and malnutrition in all its forms. The food environment is the interface of adolescent food choice and the broader food system, and food environment interventions have the potential to improve adolescent diets and nutritional outcomes. METHODS AND ANALYSIS: We will conduct a mixed-methods study, integrating methods from participatory systems science and nutritional epidemiology to characterise linkages among adolescents' neighbourhood and home food environments, and their food choices, diets and nutritional outcomes. We will recruit adolescents, caregivers, school staff and food system actors from five communities along a gradient of urban informality in Nairobi, Kenya, to participate in cognitive mapping, group-based modelling and a cohort study over one academic year to evaluate dietary choices and nutritional outcomes. ETHICS AND DISSEMINATION: The study has been approved by the Research Ethics Committee of Rutgers University (Pro2024001981) and Amref Health Africa (P1831-2025). Adult participants will provide written informed consent, and adolescents will provide written informed assent to participate in the study. Findings will be disseminated through peer-reviewed journals, conference presentations and to participants through planned participatory interaction throughout the study.