A new JAMA reported study suggests ultraprocessed foods may impact child behavior. Learn how pediatricians can guide families with practical nutrition advice.

Published: May 5, 2026

What your patients eat may shape who they become

A landmark study published in JAMA Network Open is giving pediatric providers new clinical ammunition for conversations about early childhood nutrition — and the findings go well beyond waistlines.

Studies on the link between processed food and behavior have been around for a while and evaluate the effects of food dye, added sugars, unhealthy fats, fast food and more on weight, gut microbiota and eating behavior, to name a few.

The prospective cohort study of 2,077 Canadian children found that higher ultraprocessed food (UPF) intake at age 3 was associated with more behavioral and emotional issues at age 5. Specifically, researchers found increased instances of fearfulness, anxiety, hyperactivity and aggression in children with greater UPF consumption in early childhood. Behavior was assessed using the validated Child Behavior Checklist, a widely used measure for emotional and behavioral well-being. 

“This is the first study that we have seen that is really calling to mind that children’s behavior could be influenced by ultraprocessed food,” said Erin R. Frazier, M.D., a pediatrician with Norton Children’s Medical Group, affiliated with the UofL School of Medicine. “We know that ultraprocessed food is definitely associated with increased weight, obesity, high blood pressure, diabetes and a lot of chronic diseases that we see in adulthood — but now we need to be thinking about behavioral development too.”

Understanding the scope of the problem

At age 3, UPF contributed a mean of 45.5% of total daily energy intake among the children in the study. In the U.S., the picture is similar — according to Dr. Frazier, roughly 70% of what American children eat is ultraprocessed. 

While these dietary habits can be difficult to break, the research team found that for every 10% increase in calories from UPF consumption, children had higher scores on measures of internalizing behaviors such as anxiety and fearfulness, externalizing behaviors such as aggression and hyperactivity, and overall behavioral difficulties. 

The study is also the first to examine UPF consumption and standardized behavioral assessments in children using detailed, prospective data, and one of the largest ever to examine behavior and mental health in early childhood. 

Small changes, meaningful outcomes

UPFs can be difficult to avoid. These include:

• Sugary drinks, including soda and juice
• Fast food
• Convenience food
• Processed meat
• Sugary cereals
• Packaged snacks, such as chips, crackers and cookies

One of the study’s most clinically actionable findings involves substitution rather than elimination. The researchers estimated that substituting just 150 calories — roughly equivalent to a granola bar — of ultraprocessed foods with whole fruits, vegetables or other minimally processed options was associated with better behavioral outcomes. Modeling the substitution of a portion of UPF with minimally processed foods was associated with better behavioral and emotional symptoms.

For providers, this is an important message to integrate into well-child visits: The goal is not perfection, but progress.

What to share with families

Dr. Frazier offers practical, parent-friendly guidance that fits easily into a brief counseling moment:

• Shop the perimeter. The outer aisles of the grocery store — produce, fresh proteins, dairy — tend to contain the least processed options. Inner aisles are where shelf-stable, additive-laden products dominate.
• Read the ingredient list, not just the label. Marketing claims on the front of a package can be misleading. A short ingredient list is generally a better sign than any health claim.
• Make water and milk the default drinks. Frazier is direct with families: Children do not need soda, sports drinks, tea or flavored beverages — even sugar-free varieties, which still contain additives. Study findings showed that sugary, sweetened beverages were primarily linked to adverse behavioral outcomes. 
• Lean on frozen and canned produce when fresh isn’t an option. Cost is a real barrier. Canned or frozen fruits and vegetables without added sugars are a more affordable alternative that is not ultraprocessed.
• Reconsider food as a reward. Cultural norms around snack rotations at youth sports, holiday candy and convenience store stops all add up. Dr. Frazier encourages providers to help families recognize how often food — particularly ultraprocessed food — is used as a behavioral incentive, and to gently challenge that pattern.

A note on study limitations

Providers should counsel families with appropriate nuance. The study finds an association between high UPF intake and higher emotional and behavioral symptoms, but does not establish that a UPF diet caused these outcomes. Socioeconomic factors, parental stress and access to healthy food all interact in complex ways. Study co-investigator Kozeta Miliku, M.D., Ph.D., an assistant professor at the University of Toronto, noted that parents are doing their best, and not all families have access to single-ingredient foods or the tools and time to incorporate them into their diets. 

The clinical takeaway is not alarm — it is opportunity. The preschool years are a sensitive window for brain development and the formation of dietary habits. Early supportive conversations about nutrition in the pediatric office can help families make small, sustainable shifts that may benefit children’s development well beyond the exam room.