Trends in Ultraprocessed Food Consumption Among Korean Children and Adolescents, 2007 to 2024

Importance: The prevalence of childhood obesity has tripled between 1999 and 2021, and the greatest increases have been observed in Asia. Ultraprocessed foods are considered a major risk factor for obesity; however, trends in ultraprocessed food consumption among Korean youths remain understudied. Objective: To examine 18-year trends in ultraprocessed food consumption stratified by obesity and demographic characteristics among Korean youths. Design, Setting, and Participants: This population-based cross-sectional study used 24-hour dietary recall data from 6 cycles of the Korea National Health and Nutrition Examination Survey from 2007 to 2024. Participants included Korean youths aged 1 to 18 years. Exposure: Survey cycles. Main Outcomes and Measures: The percentage of energy intake from ultraprocessed foods based on the Nova food classification system was estimated across survey cycles. Results: Among the 24 518 youths included, the weighted mean (SD) age of participants was 10.2 (5.1) years, of whom 12 797 (52.2%) were boys. From the 2007-2009 to 2022-2024 cycles, the percentage of energy from ultraprocessed foods increased from 24.6% (SE, 0.5%) to 33.0% (SE, 0.5%) (P < .001 for trend), while the percentage of energy from unprocessed or minimally processed foods decreased from 64.8% (SE, 0.5%) to 51.8% (SE, 0.4%) (P < .001 for trend). There was a greater increase in ultraprocessed food consumption among school-aged children (from 22.9% [SE, 0.6%] to 34.0% [SE, 0.6%]) and adolescents (from 28.7% [SE, 0.8%] to 36.9% [SE, 0.7%]) than among preschool-aged children (from 23.5% [SE, 0.6%] to 26.4% [SE, 0.9%]) and among youths without obesity (from 24.7% [SE, 0.5%] to 33.5% [SE, 0.5%]) than those with obesity (from 24.9% [SE, 0.8%] to 30.9% [SE, 1.1%]) (P ≤ .001 for interaction). Conclusions and Relevance: In this cross-sectional study of Korean youths, the estimated proportion of energy intake from ultraprocessed foods increased from 2007 to 2024, indicating that ultraprocessed foods became a more dominant part of Korean youths' diets, especially among older youths and those without obesity. These findings suggest the need for monitoring and preventive strategies to reduce intake.