Urban-Rural Disparities in School Lunch Food Composition: Evidence from 12.7 Million Dish Records in Taiwan's National School Food Registry.

Background/Objectives: For many schoolchildren-particularly those in low-resource areas-the school lunch is the most reliable balanced meal of the day, so its composition is a direct determinant of dietary equity. The aim of this study was to quantify urban-rural disparities in school lunch food composition at national scale and to test whether they persist once county socioeconomic structure is controlled. Methods: Using 12,688,008 dish records from 3894 schools across all 22 Taiwanese counties over 24 months (May 2024-April 2026), retrieved from the Ministry of Education's School Food Registry Platform, we constructed four dish-level dietary composition indicators-plant-forward, organic, processed, and whole-grain shares-and analyzed county-month panels (N = 418) using hierarchical regression with weighted least squares and heteroskedasticity-consistent standard errors. Results: The four dimensions followed distinct urban-rural patterns. Plant-forward provision exhibited a stable urban-to-rural decline. Organic and whole-grain provision displayed a suppressor structure: rural disadvantage disappeared-and reversed-once county income was controlled, revealing latent local supply capacity masked by income disparities. Processed-dish use, once income and population density were accounted for, was concentrated in lower-income, more densely populated counties rather than rural ones, indicating an urban concentration pattern rather than a rural deficit. A 2017 traceable-food pilot policy still exhibited a legacy effect on organic procurement seven years after its nationwide rollout. Conclusions: School meal programs thus deliver systematically different dietary environments to children in different places. Narrowing these gaps, rather than raising national averages, should be the core criterion for evaluating school lunch reform, with interventions differentiated across dietary dimensions.