Increasing food insecurity vulnerability in urban slums contrasts with regional improvements across the São Paulo Metropolitan Region, Brazil

Food insecurity remains a persistent challenge in rapidly urbanizing regions, particularly in slum areas of the Global South. While traditionally associated with poverty, socioeconomic factors alone cannot fully explain the uneven distribution of food insecurity within metropolitan areas. This study addresses critical gaps by proposing a novel Urban Vulnerability Index to Food Insecurity (UVI-FI) integrating socioeconomic conditions, health outcomes, and spatial accessibility to infrastructure in the São Paulo Metropolitan Region (SPMR) between 2000 and 2010. Using principal component analysis and geospatial techniques, we mapped food insecurity vulnerability at high spatial resolution (200 m × 200 m grid) across 39 municipalities. Results reveal significant disparities, with vulnerability increasing by 75.3% within slums while decreasing by 1.68% in the broader urban population. Spatial analysis demonstrates that vulnerability decreases with distance from slum boundaries, confirming a strong spatial gradient. The study identified critical infrastructure gaps, particularly regarding access to transportation, fresh food markets, and social assistance centers, that exacerbate food insecurity in peripheral areas. This spatially explicit framework offers valuable insights for targeting interventions in rapidly urbanizing regions.