Ultra-processed foods have long been linked to obesity, heart disease, and type 2 diabetes. Now, new research suggests they may also affect how well the brain functions, even among people who otherwise follow a relatively healthy diet.
A study involving more than 2,100 Australian adults found that higher consumption of ultra-processed foods was associated with poorer attention and slower mental processing speed. The findings add to growing evidence that the modern diet may play an important role in long-term brain health.
What The Study Found
Researchers from Monash University, the University of São Paulo, and Deakin University analyzed dietary habits and cognitive performance among middle-aged and older adults who did not have dementia.
They discovered that people who consumed more ultra-processed foods tended to perform worse on tests measuring visual attention and processing speed. Importantly, these associations remained even after accounting for factors such as education level, lifestyle habits, and overall diet quality.
Lead author Dr. Barbara Cardoso noted that the effect appeared with relatively modest increases in ultra-processed food intake. A 10% increase in consumption—roughly equivalent to adding a packet of chips to a daily diet—was associated with consistently lower scores on standardized attention assessments.
Participants in the study obtained an average of 41% of their daily calories from ultra-processed foods, closely matching Australia’s national average of 42%. Similar consumption patterns are seen across many high-income countries, where heavily processed convenience foods make up a large share of daily energy intake.
Why Ultra-Processed Foods May Affect The Brain
Ultra-processed foods include products such as soft drinks, packaged snacks, sweetened breakfast cereals, instant noodles, and ready-made meals.
These products undergo extensive industrial processing and often contain refined sugars, unhealthy fats, artificial flavorings, emulsifiers, preservatives, and color additives.
Unlike fresh or minimally processed foods, they frequently lose much of their natural fiber and food structure during manufacturing.
According to Dr. Cardoso, the combination of additives and processing-related compounds may contribute to chronic inflammation, metabolic dysfunction, and impaired vascular health—factors that are increasingly linked to cognitive decline.
One of the study’s most notable findings was that the relationship between ultra-processed foods and poorer attention persisted regardless of how closely participants followed a Mediterranean-style diet.
Even individuals who regularly consumed fruits, vegetables, legumes, and whole grains showed lower attention scores when their intake of ultra-processed foods was higher.
Links To Dementia Risk Factors
The researchers also found that higher consumption of ultra-processed foods was associated with several well-established dementia risk factors, including obesity and high blood pressure.
These conditions can damage blood vessels throughout the body, including those that supply oxygen and nutrients to the brain. For this reason, they are considered important targets for dementia prevention strategies.
The study did not identify a direct relationship between ultra-processed food consumption and memory performance. However, the authors emphasized that attention and processing speed are fundamental cognitive functions that influence learning, problem-solving, decision-making, and everyday functioning.
Subtle declines in these abilities can appear years before more noticeable memory difficulties develop. As a result, the researchers suggest that changes in attention may serve as an early indicator of broader cognitive decline among people who regularly consume large amounts of ultra-processed foods.
Study Limitations
The authors caution that the findings do not prove cause and effect.
Because the study was observational, it cannot determine whether ultra-processed foods directly caused the observed differences in cognitive performance. Dietary information was also self-reported, which can introduce inaccuracies.
In addition, participants were volunteers enrolled in a brain health project and may have been more health-conscious than the general population, potentially limiting how broadly the findings can be applied.
Nevertheless, the results are consistent with previous studies conducted in Brazil, Europe, and the United States that have linked higher ultra-processed food intake to faster cognitive decline and a greater risk of dementia.
What Happens Next
Researchers say future studies should investigate whether reducing ultra-processed food consumption can help preserve cognitive function as people age.
Long-term clinical trials are needed to determine whether dietary changes can directly improve attention, processing speed, or other aspects of brain health.
The team is also interested in exploring potential biological mechanisms behind the association, including the role of chronic inflammation, vascular health, and changes in the gut microbiome.
A Growing Concern For Brain Health
The study used data from the Healthy Brain Project, a large Australian initiative that tracks cognitive health among adults at increased risk of dementia.
While more research is needed, the findings contribute to a growing body of evidence suggesting that food quality matters not only for physical health but also for cognitive function.
The researchers conclude that limiting ultra-processed foods and choosing more minimally processed alternatives may be a practical strategy for supporting both heart and brain health over the long term.
