# 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

## TL;DR

This study evaluates how well a nutritional profiling system works for assessing diet quality in older adults using questionnaire data from two Japanese cohorts.

## Contribution

The study introduces the first nutritional profiling system for older adults and shows how modifying it improves alignment with established diet quality indices.

## Key findings

- Removing nutrient caps in the MNPS-OA significantly improved correlations with HEI-2015 and NRF9.3.
- The modified MNPS-OA (WEL-WC) showed strong convergent validity with existing diet quality indices.
- The system is adaptable for large-scale epidemiological studies and public health applications.

## Abstract

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.

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.

Cross-sectional data from the Hatoyama Cohort Study and the Kusatsu Cohort Study involving 1102 Japanese adults aged ≥65 y were utilized. Dietary data were analyzed using a validated Brief Dietary History Questionnaire. Four MNPS-OA specifications were tested: 1) original, 2) without energy limits (WEL), 3) without nutrient caps (WC), and 4) 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).

Median MNPS-OA scores ranged from 124.5 (original) to 391.6 (WEL-WC). Correlations with HEI-2015 improved from r = 0.27 (original) to 0.58 (WEL-WC), and with NRF9.3 from r = 0.26 to 0.61. Removing nutrient caps substantially enhanced convergence, whereas removing energy limits had minimal effect.

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.