A team led by researchers at the University of Toronto has found an association between ultra-processed foods in early childhood, and behavioral and emotional development.
Specifically, the team found that higher ultra-processed food consumption is linked to behavioral and emotional difficulties including anxiety, fearfulness, aggression or hyperactivity.
The preschool years are critical for child development, and it’s also when children begin to establish dietary habits.”
Kozeta Miliku, principal investigator on the study and assistant professor of nutritional sciences, U of T’s Temerty Faculty of Medicine
“Our findings underscore the need for early-life interventions such as professional advice for parents and caregivers, as well as public health campaigns, nutrition standards for child-care providers and reformulation of some packaged foods,” Miliku said.
This study, published in JAMA Network Open, is the first to examine ultra-processed food consumption and standardized behavioral assessments in kids using detailed, prospective data. It is also one of the largest ever to look at behavior and mental health in early childhood.
Ultra-processed foods are industrial formulations made largely from refined ingredients and additives not typically used in home cooking. In Canada, they make up nearly half of preschoolers’ calorie intake.
The researchers drew information from the CHILD Cohort Study, a longitudinal, population-based study that recruited pregnant women between 2009 and 2012 and followed their children from before birth through to adolescence at four sites across Canada.
The researchers looked at dietary data from over 2,000 children aged three. Two years later, when the children were five, the team assessed the preschoolers’ scores with the validated Child Behavior Checklist, a widely used measure for emotional and behavioral wellbeing in children.
The research team – which included first authors Meaghan Kavanagh (a postdoctoral fellow) and Zheng Hao Chen (a PhD student in Miliku’s lab) – found that for every 10 per cent increase in calories from ultra-processed foods, children had higher scores on measures of internalizing behaviors (such as anxiety and fearfulness), externalizing behaviours (such as aggression and hyperactivity), and overall behavioural difficulties.
Higher scores indicate more reported behavioral challenges.
Certain categories of ultra-processed foods showed stronger associations, particularly sugar-sweetened beverages and artificially sweetened drinks. Ready-to-eat and ready-to-heat foods like French fries or macaroni and cheese were linked to higher scores.
In statistical models simulating dietary change, replacing 10 per cent of energy from ultra-processed foods with minimally processed foods, such as fruits, vegetables and other whole foods, was associated with lower behavioral scores.
Miliku, who is also a researcher at U of T’s Joannah & Brian Lawson Centre for Child Nutrition, said the findings indicate that making even a few changes can make a difference toward supporting healthier development.
“Our findings suggest that even modest shifts toward minimally processed foods, like whole fruits and vegetables, in early childhood may support healthier behavioral and emotional development,” she said.
Miliku’s interest in the topic was sparked by everyday observations as a parent.
“As a parent of a toddler, I started noting how often convenience foods appear in children’s diets, sometimes even in places we consider healthy environments,” she said.
A growing body of evidence links ultra-processed foods to increased risks for obesity and cardiometabolic diseases in adults and children. Previous research has also suggested associations between these foods and adverse behavior and mental health outcomes in adolescents and adults.
“Parents are doing their best and not all families have access to single-ingredient foods, or the tools and time needed to incorporate them into their families’ diets,” said Miliku.
“Ultra-processed foods are widely available, affordable and convenient,” she added. “It is important to consider how we can gradually increase whole and minimally processed options when possible.”
Miliku said that even modest changes, such as adding a piece of fruit or swapping a sugary drink for water, may support children’s emotional and behavioral development over time.
“The goal is to provide evidence that can help families make informed choices,” she said.
This study was funded by the Canadian Institutes of Health Research and a Temerty Faculty of Medicine pathway grant.
Source:
Journal reference:
Kavanagh, M. E., et al. (2026). Ultraprocessed Food Consumption and Behavioral Outcomes in Canadian Children. JAMA Network Open. DOI: 10.1001/jamanetworkopen.2026.0434. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2845768