Abstract

Introduction: Ultra-processed foods (UPFs) are increasingly present in children's diets; however, little is known about how early feeding practices influence UPF consumption in childhood. We aimed to evaluate the association between infant feeding during the first 4 months of life (breastfeeding vs. infant formula) and UPF consumption in toddlers. Methods: This prospective study included 186 exclusively breastfed and 284 exclusively formula-fed infants recruited in Santiago, Chile. At the age of 2 years, dietary intake was assessed through 24-hour recall. The caloric contribution of UPF was estimated using the Nova food classification. Associations were evaluated using fractional probit regression models adjusted for potential confounders, including child, maternal, and household characteristics. Results: UPFs contributed 44.6% of the caloric intake of toddlers. The caloric proportion of UPFs in formula-fed children was 51.0% compared with 35.5% in breastfed children. After adjustment, formula-fed children had a 15.4 percentage point higher mean UPF intake (95% CI: 12.0-19.6; p < 0.001), mainly due to the higher intake of UPF dairy products. Around half of the breastfed children continued to receive breast milk at 2 years, accounting for 15% of the total energy intake of this group. Compared with breastfed children, formula-fed children consumed more infant or follow-up formula (11.0% vs. 6.8%, p = 0.002) and milk-based drinks (23.1% vs. 15.3%, p < 0.001) at 2 years. Conclusions: Exclusive breastfeeding in early infancy was associated with lower UPF consumption in toddlerhood. These findings support breastfeeding promotion as a strategy to reduce early exposure to UPFs and foster healthier eating habits during childhood.