Nutrition transition and nutrient inadequacy in Korea, 1998–2024: a national repeated cross-sectional trend study

Abstract Purpose Korea has undergone rapid demographic, economic, and food-system change since the late 1990s. Although previous studies have described selected nutrient and dietary trends, long-term national evidence integrating nutrient intake, food-group intake, nutrient inadequacy, dietary excess, and diet-related behaviors through 2024 remains limited. This study examined longitudinal changes in adult nutrition in Korea using published national statistics based on the Korea National Health and Nutrition Examination Survey (KNHANES). Methods We conducted a national repeated cross-sectional trend study using publicly available aggregate nutrition tables from the Korea National Health Statistics and the official Korea Health Statistics 2024 report. The primary analytic population comprised adults aged 19 years or older using published age-standardized estimates. Outcomes included energy and nutrient intake, macronutrient energy shares, food-group intake, nutrient insufficiency, energy excess, fat excess, sodium intake exceeding the chronic disease risk reduction threshold, fruit and vegetable intake of at least 500 g/day, healthy diet practices, breakfast skipping, eating out, and nutrition label use. First-to-last changes were summarized, and annual percentage changes (APCs) were estimated using weighted log-linear regression based on published standard errors. Results From 1998 to 2024, carbohydrate intake decreased from 323.5 to 253.0 g/day, whereas fat intake increased from 38.2 to 56.2 g/day. Carbohydrate energy share declined from 68.1% to 56.8%, while fat energy share increased from 16.6% to 26.6%. Sodium intake decreased from 4,951.2 to 3,279.6 mg/day; however, 68.4% of adults in 2024 remained above the chronic disease risk reduction threshold. Vitamin C intake declined by 51.0%, and iron intake declined by 28.0%. Food-group trends showed lower intake of grains, vegetables, fruits, and fish/shellfish, and markedly higher intake of beverages, meat, and dairy. Fruit and vegetable intake of at least 500 g/day decreased from 42.9% to 24.4%, while fat-excess intake increased from 23.8% to 34.4%. Nutrient insufficiency remained common, affecting 17.8% of adults in 2024. Conclusions Korea experienced a marked but mixed nutrition transition from 1998 to 2024. Lower carbohydrate and sodium intake were associated with higher exposure to total and saturated fat, displacement of several traditional nutrient-dense food groups, reduced fruit and vegetable adequacy, and persistent micronutrient vulnerability. These findings support nutrition policies that move beyond energy balance or sodium reduction alone and instead prioritize overall dietary quality, healthier fat profiles, fruit and vegetable intake, and micronutrient adequacy.