Assessing Plant-Based Diets in Taiwan Using a Harmonized Food Description-Incorporated Framework

Background: Exploring emerging dietary patterns, such as plant-based diets (PBD), often requires considerable effort to rebuild new systems or adapt existing food classification frameworks, presenting a substantial challenge for dietary research. Current systems were not originally designed for this purpose and vary in standardization and interoperability, complicating cross-study comparisons. This study aimed to adopt the harmonized, food description-incorporated, food classification system (HFDFC system) to develop a plant-based diet food classification system (PBDFC system), and to evaluate dietary intake and nutritional status among adults in Taiwan. Methods: A repeated cross-sectional design was applied using 24 h dietary recall data from the Nutrition and Health Survey in Taiwan (2013-2016 and 2017-2020), accessed via the national food consumption database. Adults aged 20-70 years were included. Data were processed through the HFDFC system to generate the PBDFC system. For each participant, the Plant-Based Diet Index (PDI), Body Mass Index (BMI), and Nutrient-Rich Food Index (NRF) were calculated and analyzed by age group. Results: Adults aged 46-70 had significantly higher O-PDI and H-PDI scores, lower Lh-PDI scores (all p < 0.0001), and higher NRF values. Despite higher average BMI, those in the highest H-PDI tertile had significantly lower BMI (p < 0.02). Conclusions: The HFDFC-based PBDFC system offers a flexible, scalable framework for plant-based diet classification and supports future cross-national research.