A team led by researchers at the University of Toronto has found a link between ultra-processed foods and behavioral and emotional development in early childhood.
Specifically, the research team found that high intakes of ultra-processed foods are associated with behavioral and emotional difficulties such as anxiety, fear, aggression, and hyperactivity.
Preschool is a critical period for a child’s development and is also the time when children begin to establish eating habits. ”
Kozeta Milik, principal investigator of the study and assistant professor of nutritional sciences, Faculty of Medicine, Temerty University
“Our findings highlight the need for early intervention, including professional advice for parents and carers, public health campaigns, nutritional standards for childcare workers, and reformulation of some processed foods,” Milik said.
This study JAMA network openwere the first researchers to use detailed prospective data to examine ultra-processed food consumption and standardized behavioral assessments in children. It is also the largest study ever to examine early childhood behavior and mental health.
Ultra-processed foods are industrial formulations made from refined ingredients and additives that are primarily not used in home cooking. In Canada, they make up nearly half of preschoolers’ caloric intake.
Researchers drew information from the CHILD Cohort Study, a population-based longitudinal study that recruited pregnant women between 2009 and 2012 and followed them from prenatal to adolescence until their children were born at four sites across Canada.
Researchers looked at dietary data for more than 2,000 3-year-old children. Two years later, when the children were 5 years old, the team assessed the preschoolers’ scores using the validated Child Behavior Checklist, which is widely used to assess children’s emotional and behavioral health.
The research team, which included lead authors Megan Kavanagh, a postdoctoral researcher, and Zhen Hao Chen, a doctoral student in Milik’s lab, found that for every 10 percent increase in calories from ultra-processed foods, children had higher measures of internalizing behaviors (such as anxiety and fear), externalizing behaviors (such as aggression and hyperactivity), and overall behavioral difficulties.
Higher scores indicate more reported behavioral challenges.
Certain categories of ultra-processed foods showed stronger associations, particularly sugar-sweetened and artificially sweetened beverages. Ready-to-eat or quick-heat foods, such as French fries and macaroni and cheese, were associated with higher scores.
In a statistical model simulating dietary changes, replacing 10 percent of the energy from ultra-processed foods with minimally processed foods, such as fruits, vegetables, and other whole foods, was associated with lower behavioral scores.
Milik, who is also a researcher at the University of Texas Joanna and Brian Lawson Center for Child Nutrition, said the study results show that making just a few changes can support healthier development.
“Our findings suggest that even modest transitions to minimally processed foods, such as whole fruits and vegetables, during early childhood may support healthier behavioral and emotional development,” she said.
Milik became interested in this topic after observing it on a daily basis as a parent.
“As a parent of a young child, I started noticing the frequent appearance of ready-to-eat foods in my child’s diet, sometimes even in what would be considered a healthy environment,” she says.
A growing body of evidence links ultra-processed foods to an increased risk of obesity and cardiometabolic disease in adults and children. Previous research has also linked these foods to harmful behaviors and mental health outcomes in adolescents and adults.
“Despite the best efforts of parents, not all families have access to single-ingredient foods or are given the tools or time needed to incorporate single-ingredient foods into their family’s diet,” Milik said.
“Ultra-processed foods are widely available, affordable and convenient,” she added. “If possible, it’s important to consider ways to gradually increase holistic and minimally treated options.”
Milik said even small changes like adding fruit or replacing sugary drinks with water can support children’s emotional and behavioral development over time.
“The goal is to provide evidence to help families make informed choices,” she said.
This research was funded by the Canadian Institutes of Health Research and the Temerty Faculty of Medicine Pathway Grant.
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Reference magazines:
Kavanagh, Maine, others. (2026). Ultra-processed food consumption and behavioral outcomes among Canadian children. JAMA network open. DOI: 10.1001/jamanetworkopen.2026.0434. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2845768
