Researchers have found that adults who eat larger amounts of a certain food group are more likely to express signs of brain damage that could increase the risk of stroke.
Experts at the Population Health Research Institute of McMaster University and Hamilton Health Sciences found that healthy participants in their study who had an increased intake of ultra-processed food were more likely to show signs of damage to the brain associated with higher stroke risk.
Ultra-processed foods are things that have ingredients not typically found at home, such as chemical-based preservatives and sweeteners. They include items such as sodas; prepackaged snacks, including chips, cookies, crackers and candy; boxed macaroni and cheese; frozen and ready-to-eat meals; lunch meats; jerky; and hot dogs.
The study was published in the journal JAMA Network Open on October 15.
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Ultra-Processed Food May Change Stroke Risk
The researchers reviewed brain magnetic resonance imaging (MRI) scans of 9,000 Canadians who were between 35 and 69 years old and had no history of heart disease.
In the study, ultra-processed food consumption represented a quarter of the participants' daily food intake on average. For those who ate the most of the food group, that proportion was 45 percent, while for those who ate the least, that number was 16 percent.
They noticed that those who had a higher consumption of ultra-processed food were 40 percent more likely to have small areas of damage in their brain, as shown on their MRI scans.
"These MRI findings are considered early warning signs," lead author Russell de Souza, who is also an associate professor at McMaster University, told Newsweek.
"People may feel completely well, but individuals with more white matter hyperintensities and silent brain infarcts are known to be at higher risk of future stroke and cognitive decline," he said. "That's why these findings are important, even in the absence of symptoms."
How Ultra-Processed Food Affects Other Risk Factors
Researchers also identified that Canadians who ate the most ultra-processed food had higher levels of body fat and more deep belly fat than those who ate the smallest amounts of the food group. Deep abdominal fat has been linked with inflammation and blood vessel damage, which can have implications on the brain, the researchers said.
The association was also found to be stronger among women, as women with the highest ultra-processed food consumption were twice as likely to show signs of this brain damage compared with those who ate the lowest proportion of the food group.
The experts also found that those with a higher consumption of ultra-processed food had a reduced consumption of whole foods, such as fruits, vegetables and other minimally processed food, while those who ate less ultra-processed food had a higher consumption of whole foods.
They said this could suggest that ultra-processed food was replacing whole food, and not that those participants were eating more of that food group on top of their usual diet.
It is not yet clear what could be behind the association. De Souza said, "We don't yet know the exact mechanism," but one possibility is that "diets higher in ultra-processed foods contribute to risk factors such as excess body fat, high blood pressure, diabetes, and other cardiometabolic conditions that can affect blood vessels throughout the body, including those that supply the brain."
"Other research teams are actively investigating whether aspects of food processing and formulation themselves may play a role," he said. "The key message is that we observed an association, but we cannot determine from this study exactly why it exists."
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What Do the Findings Mean?
"Our study suggests that diets higher in ultra-processed foods may affect the brain, not just waistlines, digestive, or heart health," de Souza said.
He added that while more research is needed, "these findings add to growing evidence supporting dietary patterns that emphasize whole, minimally processed foods and limit ultra-processed foods where possible."
He also said it's important to remember that these findings were "seen in a relatively healthy population of middle-aged adults—the average age was 58. What makes the study notable is that we observed differences in brain MRI markers before measurable differences in memory, attention, and thinking, became apparent."
Reference
De Souza, R.J., Schulze, K.M., Desai, D., et al. (2026). Ultraprocessed Food Intake and Adiposity, Vascular Brain Injury, and Cognition in Middle-Aged Adults. JAMA Network Open, 9. doi:10.1001/jamanetworkopen.2026.39118
Contact Newsweek editors on this story: Kara Dolman and Shakeema Edwards.