Canada: A new study published in JAMA Network Open found that higher consumption of ultra-processed foods at age 3 was associated with increased behavioral and emotional symptoms by age 5. The findings suggest that early exposure to ultra-processed foods may adversely affect behavioral development, consistent with prior evidence linking these foods to adverse health and mental health outcomes.Ultra-processed foods account for nearly half of the daily energy intake among preschool-aged children in Canada. However, their potential impact on children’s behavioral and emotional development has not been widely explored. To investigate this association, researchers led by Meaghan E. Kavanagh from the Department of Nutritional Sciences at the Temerty Faculty of Medicine, University of Toronto, conducted a cohort study examining the relationship between early childhood intake of ultra-processed foods and later behavioral outcomes.The researchers analyzed data from 2,077 children enrolled in the CHILD Cohort Study, a prospective Canadian pregnancy cohort. Dietary intake at age three was assessed using a 112-item food-frequency questionnaire, and foods were classified according to the NOVA food classification system by degree of processing.Behavioral outcomes were assessed at age five using the validated Child Behavior Checklist, which measures internalizing symptoms (e.g., anxiety and withdrawal), externalizing symptoms (e.g., aggression and rule-breaking), and overall behavioral difficulties. Key findings were as follows:The study included 2,077 children, of whom 52.6% were boys.Most participants were White (66.2%), while 23.1% were multiracial and 10.7% belonged to other ethnic groups.At age three, ultra-processed foods accounted for an average of 45.5% of the children’s total daily energy intake.By age five, the mean Child Behavior Checklist scores were 44.6 for internalizing symptoms, 39.6 for externalizing symptoms, and 41.2 for total behavioral difficulties.After adjusting for maternal diet, birth factors, infant feeding practices, and socioeconomic characteristics, higher intake of ultra-processed foods was associated with poorer behavioral outcomes.Each 10% increase in energy intake from ultra-processed foods was linked to higher scores for internalizing symptoms, externalizing behaviors, and overall behavioral difficulties.Replacing 10% of energy intake from ultra-processed foods with minimally processed foods was associated with lower scores for internalizing symptoms, externalizing behaviors, and total behavioral difficulties.Overall, the findings suggest that higher consumption of ultra-processed foods during early childhood may contribute to adverse behavioral and emotional symptoms by preschool age. The researchers noted that encouraging minimally processed foods in children’s diets could support healthier behavioral development and may have long-term benefits for mental health.Reference:Kavanagh ME, Chen ZH, Tamana SK, et al. Ultraprocessed Food Consumption and Behavioral Outcomes in Canadian Children. JAMA Netw Open. 2026;9(3):e260434. doi:10.1001/jamanetworkopen.2026.0434