Application of a Food-Based Nutritional Profiling System to Assess Diet Quality in Diet-Level Data: Evidence on Construct and Convergent Validity from the Hatoyama Cohort Study and Kusatsu Cohort Study

Background: Nutritional Profiling Systems (NPSs) are designed to classify foods by nutritional quality, but most validations occur at the food level. Their applicability to diet-level data from dietary questionnaires-commonly used in epidemiology-remains unclear. Objectives: The study aims to evaluate the construct and convergent validity of the Meiji NPS for Older Adults (MNPS-OA), the first NPS developed for older populations, when applied to diet-level data. Methods: ) without energy limit and nutrient caps (WEL-WC). Construct validity was assessed by intermodel correlations; convergent validity was evaluated against Healthy Eating Index-2015 (HEI-2015) and Nutrient-Rich Food Index 9.3 (NRF9.3). Removing nutrient caps substantially enhanced convergence, whereas removing energy limits had minimal effect. Conclusions: MNPS-OA can be adapted for diet-level assessment with targeted modifications. Eliminating nutrient caps markedly improves alignment with established diet quality indices, supporting its potential use in large-scale epidemiological studies and public health applications.