In Brief
- Every 10 per cent rise in ultra-processed foods can worsen focus and slower thinking.
- These effects occur even in people following otherwise healthy diets.
A new study has found that diets high in ultra-processed foods (UPFs) could be quietly undermining brain function, even among people who otherwise follow healthy eating patterns.
The data analysed from more than 2,100 dementia-free Australians, who were middle-aged and older, found that a diet high in heavily processed foods can negatively impact the brain's ability to focus, and increase the risk of developing dementia.
The research, led by Monash University, found that even modest increases in UPF consumption were linked to declines in attention.
Lead author Dr Barbara Cardoso said the effects were both consistent and measurable.
“For every 10 per cent increase in ultra-processed food a person consumed, we saw a distinct and measurable drop in a person’s ability to focus.”
She said a 10 per cent increase in UPFs is roughly equivalent to adding a standard packet of chips to your daily diet.
In clinical terms, this translated into lower scores on standardised tests, with a decrease in focus and slower thinking.
What counts as ultra-processed food?
Ultra-processed foods include widely consumed items such as soft drinks, packaged salty snacks and ready-made meals — products that are far removed from their original wholefood form.
Participants in the study consumed an average of 41 per cent of their daily energy from these foods, closely aligning with Australia’s national average of 42 per cent.
“The more ultra processed foods they consumed, the worse their capacity was to focus or concentrate," Dr Cardoso told SBS News.
“The data suggests that these foods can be detrimental to cognitive health, starting from the young adulthood stage of life."
Healthy diets not a safeguard
One of the study’s most significant findings was that that UPFs had negative effects regardless of overall diet quality.
Even individuals following otherwise healthy dietary patterns, including Mediterranean-style diets, experienced declines in attention when they increased their intake of UPFs.
This suggests that how food is processed may matter just as much as what nutrients it contains.
“The adherence to a Mediterranean-style diet did not counterbalance the negative association we found for ultra-processed foods,” Dr Cardoso said.
She noted that ultra-processing of food often destroys its natural structure, introducing potentially harmful substances like artificial additives or processing chemicals.
‘They end up transforming the food matrix to remove some important components of the food and also adding some other ingredients that we don’t normally have in our pantry like emulsifiers [and] colourants, which seem to have detrimental health effects.”
A warning sign for long-term brain health
While the study did not find a direct link between ultra-processed foods and memory loss, researchers emphasised that attention is a foundational cognitive function.
It underpins critical processes such as learning, decision-making and problem-solving, meaning even subtle declines could have broader implications over time.
Higher consumption of UPFs was also associated with increased dementia risk factors, including conditions like high blood pressure and obesity, which are managed to help protect brain health.
“We know that ultra-processed foods are associated with cardiovascular disease and Type 2 diabetes, which are conditions tightly associated with dementia risk,” Dr Cardoso said.
A growing area of concern
The findings add to a growing body of evidence suggesting that industrial food processing itself, not just poor nutrition, may play a role in cognitive decline.
With ultra-processed foods making up a significant portion of the average Australian diet, researchers say the results highlight the importance of looking beyond traditional definitions of “healthy eating”.
One form of dementia closely linked to lifestyle factors is vascular dementia, caused by damage to blood vessels in the brain.
While there is currently no treatment, researchers at UNSW Sydney have just mapped out new potential genetic targets aimed at developing future therapies.
Dr Matthew Lennon from the University of NSW told SBS News that this research looks at what medications could be repurposed, and what new molecules could be invented to try to target these genes.
He added a large proportion of the risk is linked to lifestyle and genetics, including things like high blood pressure, diabetes, cholesterol and obesity.
The Monash University study draws on data from the Healthy Brain Project and was supported by organisations including the National Health and Medical Research Council, and the Alzheimer’s Association.
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