Canadian Study Links Ultra-Processed Foods in Early Childhood to Behavioral Difficulties

A recent Canadian cohort study has identified an association between the consumption of ultra-processed foods (UPFs) in early childhood and the development of behavioral and emotional difficulties, including increased anxiety, fearfulness, aggression, and hyperactivity. The research, published in JAMA Network Open, suggests that even modest dietary shifts away from UPFs towards minimally processed foods (MPFs) may be linked to improved behavioral outcomes in children.

Study Design and Methodology

The study, led by a research team including Kozeta Miliku, an assistant professor at the University of Toronto's Temerty Faculty of Medicine, is reported to be the first to examine UPF consumption and standardized behavioral assessments in children using detailed, prospective data. It represents one of the largest studies on behavior and mental health in early childhood.

Researchers utilized data from the CHILD Cohort Study, analyzing information from 2,077 Canadian children.

• Dietary intake was assessed at age three using a food frequency questionnaire (FFQ) and categorized according to the NOVA system.
• Two years later, at age five, the children's behavioral and emotional outcomes were evaluated through caregiver-reported Child Behavior Checklist (CBCL) T-score scales.

To ensure robust findings, the study accounted for several potential confounding factors. These included maternal education and marital status, prenatal stress, maternal UPF intake during pregnancy, child's sex and ethnicity, gestational age, breastfeeding status, overall calorie intake, childcare exposure, physical activity levels, body mass index, household income, the presence of older siblings, study site, and season.

Key Findings

The research revealed several associations regarding UPF consumption and children's behavior:

At three years of age, ultra-processed foods constituted a median of 46% of the total calorie intake among participants.

• For every 10 percent increase in calories derived from ultra-processed foods at age three, children exhibited small increases (generally less than 1 T-score point) in CBCL scores for internalizing behaviors (such as anxiety and fearfulness), externalizing behaviors (such as aggression and hyperactivity), and overall behavioral difficulties at age five. Higher scores indicate increased reported behavioral challenges.
• Specific categories of ultra-processed foods showed stronger associations, including sugar-sweetened beverages, artificially sweetened drinks, and ready-to-eat/ready-to-heat foods (e.g., French fries, macaroni and cheese). Subgroup analyses indicated that higher intake of artificially sweetened and sugar-sweetened beverages, breads, and ready-to-eat foods was associated with increased internalizing symptoms.

Statistical models indicated that replacing 10 percent of energy from ultra-processed foods with minimally processed foods, such as fruits and vegetables, was associated with modestly lower CBCL scores across internalizing, externalizing, and total behavioral domains.

• The observed associations did not differ significantly between boys and girls.

Implications and Recommendations

Kozeta Miliku highlighted the significance of the findings, stating that they underscore the potential importance of early-life interventions.

"These could include professional advice for caregivers, public health campaigns, nutrition standards for childcare providers, and the reformulation of packaged foods," Miliku stated.

The research team further noted that even modest dietary shifts may support healthier behavioral and emotional development.

The study's findings align with public health strategies promoting whole-food dietary patterns, consistent with guidance such as Health Canada’s Canada’s Food Guide. Researchers suggest that strengthening early-life nutrition efforts — including family guidance, childcare nutrition standards, and limiting the marketing of highly processed foods to children — may support healthy development. The study aims to provide evidence to help families make informed dietary choices, while acknowledging that ultra-processed foods are widely available, affordable, and convenient.

Further studies with more precise dietary assessments are recommended to clarify the long-term behavioral and mental health impacts of ultra-processed food consumption.

Funding for this study was provided by the Canadian Institutes of Health Research and a Temerty Faculty of Medicine pathway grant.