Ultra-Processed Food Intake Is Associated with Dietary Quality, Dental Caries, and Constipation-Related Symptoms Among Preschool Children in Taiwan: A Cross-Sectional Study

Background/Objectives: Evidence on ultra-processed food (UPF) consumption and health among East Asian preschoolers is limited. We examined associations with nutrient intake, anthropometry, dental caries, and bowel symptoms in Taiwan. Methods: This cross-sectional study included 822 children aged 2–6 years. A caregiver-reported 107-item food frequency questionnaire estimated UPF energy contribution using an adapted NOVA framework; anthropometric and dental data were available for 777 and 746 children, respectively. Results: UPFs supplied 15.12% of energy. Higher UPF intake was associated with lower fiber, protein, and several micronutrient intakes and higher saturated fat and sodium intakes, without significant anthropometric differences. Caries prevalence was 12.8% in Q1 and 31.2% in Q4 (adjusted prevalence ratio [aPR] = 2.27, 95% confidence interval [CI]: 1.48–3.48). Relative to Q1, Q3 showed higher prevalences of infrequent bowel movements (aPR = 1.48, 95% CI: 1.09–2.00) and hard stools (aPR = 1.23, 95% CI: 1.01–1.49); Q4 associations were not statistically significant. Exploratory food-group analyses associated fruit intake with lower reported frequency of infrequent bowel movements and biscuit/snack intake with higher hard stool frequency. Conclusions: Higher UPF intake was associated with unfavorable nutrient profiles, dental caries, and selected caregiver-reported bowel symptoms, but not anthropometric status. Further longitudinal studies are warranted to clarify the temporal relationships between UPF consumption and these health outcomes during early childhood.