Bold claim: Early ultra-processed foods may shape how kids behave and feel later on. And this is where the discussion gets truly important. A team from the University of Toronto has found a link between consuming ultra-processed foods in early childhood and later behavioral and emotional development issues, with the connection showing up in several areas of behavior.
In the study, researchers observed that higher intake of ultra-processed foods during the preschool years is associated with greater difficulties in behavior and emotion, including anxiety, fearfulness, aggression, and hyperactivity. Kozeta Miliku, the study’s lead investigator and an assistant professor of nutritional sciences at the University of Toronto’s Temerty Faculty of Medicine, emphasizes that early childhood is a critical window for both growth and the formation of dietary habits. She notes that these findings point to the potential value of early-life interventions—such as professional guidance for parents and caregivers, public health campaigns, clearer nutrition standards for child-care providers, and reformulation of certain packaged foods—to support healthier development.
The study, published in JAMA Network Open, is notable for being among the first to connect ultra-processed food consumption with standardized behavioral assessments in children using detailed, prospective data. It also stands as one of the largest investigations into behavior and mental health in early childhood to date.
Ultra-processed foods are industrial formulations built largely from refined ingredients and additives that are not typically used in home cooking. In Canada, these foods account for roughly half of preschoolers’ daily caloric intake, underscoring how pervasive they are in young children’s diets.
Data for the research came from the CHILD Cohort Study, a long-term, population-based project that enrolled pregnant women between 2009 and 2012 and followed their children from before birth through adolescence across four Canadian sites. Dietary information was collected for over 2,000 children aged three. When these children reached age five, researchers assessed their behavioral and emotional health using the validated Child Behavior Checklist, a widely used instrument for measuring child wellbeing.
The team—led by Miliku with first authors Meaghan Kavanagh (a postdoctoral fellow) and Zheng Hao Chen (a PhD student in Miliku’s lab)—found that for every 10 percent increase in calories derived from ultra-processed foods, children scored higher on measures of internalizing behaviors (like anxiety and fearfulness), externalizing behaviors (such as aggression and hyperactivity), and overall behavioral problems. Higher scores indicate more behavioral challenges reported by caregivers or evaluators.
Certain ultra-processed food categories showed stronger associations. In particular, sugar-sweetened beverages and artificially sweetened drinks stood out, along with ready-to-eat or ready-to-heat items like French fries and macaroni and cheese, which correlated with higher behavioral problem scores.
In models simulating dietary changes, replacing 10 percent of energy from ultra-processed foods with minimally processed options—such as fruits, vegetables, and other whole foods—was linked to lower behavioral problem scores.
Miliku, who also conducts research at the Joannah & Brian Lawson Centre for Child Nutrition at U of T, stresses that the findings suggest even modest dietary shifts toward less-processed foods can positively influence development. “Our results imply that small changes—like incorporating more whole fruits and vegetables in early childhood—may support healthier behavioral and emotional outcomes,” she said.
Her motivation partly came from everyday observations as a parent. She recalls noticing how convenient foods appear frequently in children’s diets, even in settings we might consider healthy.
Beyond this study, a growing body of evidence ties ultra-processed foods to higher risks of obesity and cardiometabolic conditions in both adults and children. Prior research has also suggested links between these foods and adverse behavioral and mental health outcomes in older youths and adults.
Miliku acknowledges that not all families have easy access to single-ingredient foods or the time and resources to prepare them. She notes that ultra-processed foods are widely available, affordable, and convenient, which makes it all the more important to explore gradual ways to increase the proportion of whole or minimally processed foods in children’s diets.
Even small steps—such as offering a piece of fruit or swapping a sugary drink for water—may contribute to better emotional and behavioral development over time. The overarching aim is to provide evidence that helps families make informed, healthier choices.
The study was funded by the Canadian Institutes of Health Research and a Temerty Faculty of Medicine pathway grant. Public release notes indicate the material reflects the authors’ views and that the information has been edited for clarity and length.
Would you consider small, achievable changes in your household to favor minimally processed foods, and what barriers do you foresee in making those changes? Share your thoughts below.
