Effect of breastfeeding on dietary patterns in early childhood: the CoAlHaS study

Purpose This study assessed the association between breastfeeding practices during the first year of life and later diet quality at ages 4 and 6 years, focusing on unprocessed/minimally processed foods (MPFs) and ultra-processed foods (UPFs). Methods We analyzed data from 574 children participating in the CoAlHaS study, a prospective birth cohort conducted in Santander, Spain. Breastfeeding status was recorded at 6 months (exclusive, mixed or infant formula), and at 12 months (continued breastfeeding or infant formula). Dietary intake at ages 4 and 6 years was assessed using the Food Propensity Questionnaire from the ENALIA study, developed for the Spanish population of children and adolescents. Foods were classified according to the NOVA system. Logistic regression estimated odds ratios (OR) for high MPFs and UPFs intake (highest vs. lower tertiles), adjusting for sociodemographic, anthropometric, lifestyle variables, and total energy intake. Results Exclusive breastfeeding at 6 months was associated with higher odds of high MPFs intake at age 4 (OR 2.2; 95% CI 1.14–4.34), but this was not significant at age 6 after adjustment. Conversely, exclusive breastfeeding consistently protected against high UPFs intake, remaining significant at age 6 (OR 0.46; 95% CI 0.23–0.91) in fully adjusted models. Continued breastfeeding at 12 months showed a slightly weaker protective association at age 6 (OR 0.55; 95% CI 0.31–0.97). Conclusion Exclusive breastfeeding for 6 months may contribute to healthier dietary patterns in early childhood, particularly by reducing ultra-processed food consumption, with protective effects persisting until school age.