Associations between diet quality and regional factors in Korea vary according to individuals' characteristics: a cross-sectional study.

Objectives: Although diet quality is known to be associated with environment and individuals' characteristics, these have not been studied together. We determined the association of diet quality with regional factors stratified by individuals' sociodemographic characteristics. Methods: This study used nationally representative survey data on regional factors (2010-2020) and the Korea National Health and Nutrition Examination Survey data on individuals' sociodemographic characteristics (2013-2018). Community-dwelling Koreans aged ≥ 20 were included (n = 26,853). Regions were categorized into metropolitan cities or provinces and subsequently according to regional factors (level of educational attainment, income per capita, food security status, physical activity facilities, time to the nearest large retailer, and internet use of the region). Individuals' sociodemographic characteristics included age, education status, income, and number of household members. Diet quality was assessed using the Korean Healthy Eating Index (KHEI). Results: In the entire population, education status of metropolitan cities was positively associated with the KHEI. Shorter time to retailers and higher internet use were positively associated with the KHEI in metropolitan residents with higher income levels but negatively associated with the KHEI in those with lower income status. Among provincial residents with a low education status or income, regional physical activity facilities were positively associated with the KHEI. Conclusion: The association between diet quality and regional factors varied depending on the resident's sociodemographic characteristics. Both regional and individual sociodemographic factors must be considered to address gaps in nutritional equity.