New research from CHILD has found that children who consume higher amounts of ultraprocessed foods at three years of age tend to exhibit more behavioural and emotional difficulties by age five.
These findings, published in JAMA Network Open, highlight the importance of early-life nutrition as a potentially modifiable factor in child behavioural development and strengthening early-life nutrition policies and practices to support healthy behavioural development.
Ultraprocessed foods are industrially formulated products made largely from refined ingredients and additives not typically used in home cooking. They are often convenient, ready-to-eat, shelf-stable and heavily marketed. Common examples include sugary drinks, packaged snacks, instant noodles, ready-to-heat meals, cold cereals, and processed meats.
The researchers analyzed data from 2077 CHILD participants, for whom dietary information had been collected at age 3 and behavioral outcome data at age 5.
“At the five-year visit, behavior and emotional outcomes were assessed using the Child Behavior Checklist questionnaire, completed by a caregiver,” comments author Dr. Meaghan Kavanagh, a Banting Postdoctoral Research Fellow in the Department of Nutritional Sciences at the University of Toronto and Department of Nutrition at the Harvard T.H. Chan School of Public Health.
“The tool includes questions about inward-focused behavior like anxiety, fearfulness, and depression, about outward-directed behaviour like aggression and hyperactivity, as well as question about sleep-related and other challenges.”
The researchers found that each 10% increment in calories from ultraprocessed foods to a child’s overall diet (equivalent to roughly 150 calories) was associated with higher scores across all behavioural domains — internalizing, externalizing and total difficulties. Higher scores indicate more reported behavioural challenges.
They also found that certain categories of ultraprocessed foods showed stronger associations, particularly sugar-sweetened beverages and artificially sweetened drinks.
The team statistically modeled the effects of substituting 10% of energy from ultraprocessed foods for the equivalent energy from minimally processed foods (e.g. fruits, vegetables and other whole foods) and found that such a dietary change may result in improved behavioural and emotional outcomes.
Consistent with previous research, CHILD has also linked higher ultraprocessed food consumption to adverse cardiometabolic outcomes in children. However, this is the first study to examine ultraprocessed food intake and child behavioural outcomes.
What’s the connection between diet and behavioural development? While this is not entirely understood, some links have been identified.
“Ultraprocessed foods are generally low in fiber and micronutrient density, while high in saturated fat, sugars, sodium, and additives ” notes co-author Zheng Hao Chen, PhD student in the Miliku Lab at the University of Toronto.
“Diets high in these components have been linked to inflammatory processes, alterations in gut–brain signaling and changes in stress responsivity — all of which may influence neurodevelopment.”
It also appears that energy from ultraprocessed foods often replaces nutrient-dense foods, contributing to deficiencies in nutrients that have been associated with depression-related outcomes in children and adolescents. Additionally, ultraprocessed foods may influence the gut microbiome—the community of organisms that live in our digestive tract and contribute to our overall health—as well as immune and inflammatory responses, all of which potentially impact brain function.
“While the exact mechanisms require further investigation, the associations we observed are important, particularly given that ultraprocessed foods account for nearly half of the daily calorie intake of Canadian preschoolers,” observes senior author Dr. Kozeta Miliku, a professor of Nutritional Sciences at the University of Toronto and Clinical Science Officer for CHILD.
“Early childhood is a critical developmental window, when dietary patterns and behavioural trajectories are being established. Even modest shifts toward minimally processed foods may have meaningful implications at the population level.
“So, these findings highlight a promising area we can target to help improve mental health in childhood and beyond—by such means as professional healthcare guidance for families, public health campaigns and improved childcare nutrition standards and broader food policy initiatives.”