A Canadian study has identified a concerning association between diets rich in ultra-processed foods and signs of brain damage among adults who appeared healthy. The findings also linked heavier consumption with an increased risk of stroke and future memory problems.

Researchers used magnetic resonance imaging scans to examine the brains of about 9,000 participants. They found small areas of damage more often among people who consumed large amounts of ultra-processed foods, including soft drinks, packaged snacks and sugary breakfast cereals.

Participants with the highest intake of ultra-processed foods were 40% more likely to display these brain changes. According to Medical Xpress, the damage can remain undetected because it does not produce obvious symptoms.

The changes can, however, serve as early warning signs years before a stroke or memory problems emerge. Russel J. de Souza, the study’s first author and an associate scientist at the Population Health Research Institute of McMaster University and Hamilton Health Sciences, called the findings unexpected.

“Usually, this kind of damage is associated with conditions we hear about and treat at a much older age,” de Souza told Medical Xpress. He noted that the research focused on “middle-aged Canadians who had no heart problems and reported no other health concerns.”

The study was published in JAMA Network Open and included participants between the ages of 35 and 69. In addition to brain changes, researchers examined body fat and dietary patterns.

Participants who ate the most ultra-processed foods had more body fat and visceral fat. Visceral fat is stored deep in the abdomen and is linked to health concerns including heart disease.

The association between ultra-processed food consumption and brain damage was stronger among female participants. Women in the highest consumption group had nearly twice the likelihood of showing signs of brain damage compared with women in the lowest group.

“Our findings suggest that the link between diet and brain health may be detectable before people experience noticeable problems with memory or thinking,” said Sonia Anand, the study’s senior author and a senior scientist at the Population Health Research Institute.

Ultra-processed foods are generally appealing to consumers, but they often lack important nutrients such as fiber, vitamins and minerals, according to the CDC. They can also contain high amounts of sodium, saturated fats and added sugars.

CDC data published in August 2025 showed that ultra-processed foods accounted for an average of 55% of total daily calories among Americans ages one year and older. The data covered the period between August 2021 and August 2023.

Anand said convenience and widespread availability could contribute to heavy consumption. She warned that “diets high in these foods may be linked to brain changes that may lead to memory loss and stroke” in the future.

Among participants in the Canadian study, ultra-processed foods represented an average of about 25% of daily food intake. Researchers also observed that consumption of nutrient dense foods declined as intake of ultra-processed products increased.

Whole foods such as fruits, vegetables and grains accounted for 41% of daily food intake among participants who ate the most ultra-processed food. The figure rose to 68% among those who consumed the least.

Although the findings revealed a connection between ultra-processed food consumption and indicators of brain changes, they did not establish direct causation. Participants were evaluated only once and were not tracked in the future, preventing researchers from determining whether the foods caused the observed damage.

“We need longer-term studies that track people over time with repeated MRI scans to find out whether reducing ultra-processed food intake can slow or prevent these brain changes,” de Souza said. He added that additional research is in the works.