Ultra-Processed Food Intake Is Associated with High Consumption of Added Sugar and Sodium in U.S. Infants.

Background/Objectives: Ultra-processed food (UPF) consumption has been connected to adverse outcomes in children and adults, but research in infants is limited. This study assesses the relationship between UPF, dietary intake, and infant growth during complementary feeding. Methods: We analyzed infant UPF intake from 3-day diet records at ages 5, 9, and 12 months (n = 114). Two coders independently classified foods from diet records using the Nova classification system. Linear mixed-effects models were used to model dietary intake and growth outcomes. A Bonferroni-corrected p-value of 0.006 (9 tests) was used for multiple testing. Results: UPF intake significantly increased from 9 to 12 months (9 (7, 13)vs. 20 kcal/kg/d (17, 23), p < 0.0001), accounting for 30% of total energy at 9 months and 38% at 12 months. UPFs were associated with both added sugar at 9 (β = 0.27 [0.19, 0.36], p < 0.0001) and 12 months (β = 0.25 [0.2, 0.3], p < 0.0001), and sodium at 9 (β = 16.08 [10.87, 21.29], p < 0.0001) and 12 months (β = 12.39 [8.15, 16.64], p < 0.0001). Intake of minimally processed foods (Nova 1) was associated with lower added sugar intake (β = -0.22 [-0.27, -0.18], p < 0.0001). Conclusions: In this cohort of U.S. infants, UPFs had lower nutrient density and higher energy density, with foods such as savory snacks and bars frequently contributing to dietary sodium and added sugar. These findings may suggest that limiting UPFs, especially toddler-specific products, and emphasizing minimally processed foods during complementary feeding could improve adherence to dietary guidance.