Breastfeeding, consumption of ultraprocessed foods, and dental caries at 4 years of age: A birth cohort study.

BACKGROUND: Cohort studies have demonstrated an association between prolonged and/or frequent breastfeeding and early childhood caries (ECC). AIM: To investigate the association between prolonged breastfeeding and ECC at 48 months, while considering the interaction between prolonged breastfeeding and ultraprocessed foods (UPF). DESIGN: Data from a birth cohort study conducted in southern Brazil were used (n = 3645). Poisson regression was used to evaluate the influence of breastfeeding and UPF consumption on the prevalence and experience of caries. To measure the interaction on the additive scale between breastfeeding and UPF consumption on the prevalence and experience of ECC, the relative excess risk due to interaction (RERI) was calculated. RESULTS: Prolonged breastfeeding was associated with higher prevalence (PR = 1.82; CI:1.59-2.08) and experience (RR = 2.47; CI:1.97-3.10) of ECC. Greater prevalence (PR = 1.16; CI: 1.04-1.30) and experience of ECC (RR = 1.22; CI: 1.00-1.48) were found in children who had high consumption of UPFs. Negative RERIs were observed for the prevalence and experience of ECC (-0.25 and -0.001). CONCLUSION: High UPF consumption and prolonged breastfeeding were associated with ECC. No interaction, however, was observed, showing that the two exposures have independent effects. To prevent ECC, policies and programs are needed to support breastfeeding until the age of 2 years and to limit the consumption of UPF.