Healthy adults who eat high amounts of ultra-processed food, like packaged snack foods, sugary breakfast cereals, soft drinks, instant noodles and ready-to-eat frozen meals, are more likely to have signs of damage to the brain that may increase the chances of clinical stroke and future memory problems.

Researchers used magnetic resonance imaging (MRI) to scan the brains of nearly 9,000 people and detected tiny areas of damage more frequently in participants who ate the most ultra-processed food compared with those who ate the least. Participants with the highest intake were 40% more likely to show these changes, which produce no obvious symptoms but are considered early warning signs that can appear years before a stroke or memory problems begin.

“I would not have expected this finding, frankly. We studied middle-aged Canadians who had no heart problems and reported no other health concerns,” said Russell J. de Souza, first author of the study and an associate scientist at the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences, and an associate professor in Health Research Methods, Evidence, and Impact and the Heersink School of Global Health and Social Medicine at McMaster University.

“Usually, this kind of damage is associated with conditions we hear about and treat at a much older age.” Published in JAMA Network Open, the PHRI-led study enrolled Canadians between the ages of 35 and 69 with no history of heart disease from communities across Canada.

Participants who ate the most ultra-processed food also carried more body fat and more deep belly fat than those who ate the least. This type of abdominal fat is linked to inflammation and blood vessel damage that can also reach the brain. The association between ultra-processed food and brain damage appeared stronger among women. Those in the highest consumption group were nearly twice as likely to show signs of brain damage compared with those 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, senior author of the study and senior scientist at PHRI. “This adds to the growing evidence that what Canadians eat in their 30s, 40s, 50s and 60s shapes their brain health later in life.”