A new study suggests that eating more ultra-processed foods can make it harder to stay focused, even for people who eat a healthy diet, and may contribute to factors associated with dementia.
Researchers from Monash University, University of São Paulo and Deakin University analyzed dietary and cognitive data from more than 2,100 middle-aged and older Australian adults without dementia. Their discovery is Alzheimer’s disease and dementia: diagnosis, evaluation, and disease monitoringJournal of the Alzheimer’s Association.
Ultra-processed foods and attention span
The study found that even small increases in ultra-processed food consumption were associated with measurable decreases in attention and mental processing speed.
Lead author Dr Barbara Cardoso, from Monash University’s School of Nutrition, Dietetics and Food Studies and the Heart Institute of Victoria, said the results add to growing evidence linking highly processed foods to poor brain health.
“To put our findings into perspective, a 10 percent increase in UPF is roughly equivalent to adding a standard bag of chips to your daily diet,” Dr. Cardoso said.
“We found that for every 10% increase in the amount of ultra-processed food a person consumed, there was a clear and measurable decrease in their ability to concentrate.
“In clinical terms, this led to consistently lower scores on standardized cognitive tests that measure visual attention and processing speed.”
Participants in the study consumed around 41 per cent of their daily calories from ultra-processed foods, which is roughly in line with Australia’s national average of 42 per cent.
Why food processing is important
Ultra-processed foods (UPFs) include products such as soft drinks, salty packaged snacks, and ready-made meals. Unlike fresh or minimally processed foods, these products undergo extensive industrial processing.
One of the study’s most notable findings was that the negative effects on attention appeared regardless of a person’s overall diet quality. A similar relationship was found between increased intake of ultra-processed foods and decreased concentration in participants who generally followed a healthy Mediterranean-style diet.
According to the researchers, this suggests that the level of processing itself may play an important role.
“Ultra-processing of food often destroys the natural structure of the food and introduces potentially harmful substances such as artificial additives and processing chemicals,” Dr. Cardoso said.
“These additives suggest that the relationship between diet and cognitive function goes beyond simply not consuming foods known to be healthy, and point to mechanisms related to the degree of food processing itself.”
Association with risk factors for dementia
Researchers also found that increased intake of ultra-processed foods was associated with increases in known dementia risk factors. These include conditions such as obesity and high blood pressure, both of which can be managed to support long-term brain health.
Although the study did not identify a direct link between ultra-processed foods and memory loss, the researchers noted that attention is a fundamental cognitive function. It plays an important role in learning, problem solving, and many other mental tasks.
Because attention is fundamental to so many aspects of thinking, a decline in concentration may be an important early warning sign of broader cognitive changes.
Research team and funding
The study was led by Dr. Barbara Cardoso. Co-authors include Dr Lisa Bransby, Hannah Cummins, Professor Yen Yin Lim and Xin-Yi Yuan from Monash University. Dr. Euridis Martínez Steele of the University of São Paulo; Dr Barbara Breiner and Dr Priscilla Machado from Deakin University.
The study used data from the Healthy Brain Project, which is supported by the National Health and Medical Research Council (NHMRC), the Alzheimer’s Society, the Australian Dementia Research Foundation, the Bethlehem Griffith Research Foundation, the Ylgilver Alzheimer’s Disease Research Program, the National Heart Foundation of Australia, and the Alzheimer’s Disease Charleston Conference. Dr. Euridice Martinez Steele received funding from FAPESP (2023/16144-3), Dr. Priscila Machado from the NHMRC Emerging Leadership Fellowship (APP2034008), and Professor Yen Ying Lim from the NHMRC Career Development Fellowship (GNT1162645) and Emerging Leadership Grant (GNT2009550).
