Study Links Ultra-Processed Foods to Brain Changes Similar to Silent Strokes

A new study from McMaster University, published in JAMA Network Open in October 2026, found that people who eat large amounts of ultra-processed foods show brain changes similar to those caused by silent strokes, a type of brain injury that occurs without obvious symptoms but raises the long-term risk of vascular dementia.

Researchers analyzed brain MRI scans from 8,700 adults with a median age of 58. Participants who consumed the most ultra-processed foods had a higher prevalence of white matter lesions, small areas of damage in the brain's white matter that are associated with impaired blood flow. These lesions are a known marker for increased dementia risk.

Ultra-processed foods include items like packaged snacks, fast food, sugary drinks, and ready-to-eat meals that contain artificial additives, preservatives, and flavor enhancers. They are typically high in calories and low in fiber, vitamins, and other nutrients.

The researchers believe the link between ultra-processed foods and brain damage may be driven by several mechanisms. These foods promote chronic inflammation, which can damage blood vessels in the brain. They may also disrupt the gut microbiome, triggering systemic inflammation that affects neurological health. Additionally, their low nutritional density may deprive the brain of compounds needed for healthy function.

The McMaster team plans to follow 2,000 participants in a future study to determine whether reducing ultra-processed food intake leads to measurable improvements in brain health.

The findings add to a growing body of research connecting diet to cognitive outcomes. A separate study published in the American Journal of Public Health in June 2026 found that older adults with the highest ultra-processed food intake faced a 58 percent higher risk of developing dementia over a nine-year period.