For years, doctors have warned that potato chips, cookies, and sodas may expand your waistline, cause heart disease, and shave years off your life. Now, a new study has added to evidence that they may also harm cognition and thinking abilities.
Study Details
In the paper, researchers in Australia analyzed the diets of 2,200 middle-aged adults to find out how what they ate affected their cognitive function. Diets were checked for consumption of ultra-processed foods. There is no universal definition of ultra-processed foods, but they are widely thought to be those with more than five ingredients or foods that contain at least one ingredient not found in a typical kitchen.
Overall, they found that those who ate more ultra-processed foods had a worse ability to focus and poorer cognitive health. For every 10 percent increase in ultra-processed foods in a participant's diet—equivalent to one 'standard' packet of potato chips a day—the researchers said they had lower attention spans and a higher score of dementia risk factors. That shift was recorded regardless of what else the participants ate and whether they followed an otherwise healthy diet.
Expert Insights
Dr. Barbara Cardoso, a nutritional biochemist at Monash University who led the research, said: 'To put our findings in perspective, a 10 percent increase in ultra-processed foods is roughly equivalent to adding a standard packet of chips to your daily diet. For every 10 percent increase in ultra-processed food a person consumed, we saw a distinct and measurable drop in a person's ability to focus. In clinical terms, this translated to consistently lower scores on standardized cognitive tests measuring visual attention and processing speed.'
Potential Mechanisms
The study did not elaborate on why the foods harm brain health, but the researchers said processing may remove vital nutrients and add dangerous chemicals that can damage the brain. The researchers noted that the foods may contain acrylamide, a compound that forms in starchy foods during high-temperature cooking such as frying or roasting, that can damage neurons or blood vessels. Previous research has also shown ultra-processed foods may contain phthalates or bisphenols, chemicals that can enter the food during processing, which can also be potentially harmful.
In the paper, they warned the chemicals could cause cerebrovascular lesions—or tiny areas of damaged brain tissue caused by an insufficient blood supply due to damage to a blood vessel. The scientists said that these small areas of damage may harm brain function, potentially leading to problems with focus and attention span—and raising the risk of suffering from dementia. Ultra-processed foods are also linked to a higher risk of being obese or having high blood pressure or diabetes, which can also raise the risk of dementia—which currently affects 7 million Americans.
Limitations and Context
The study was observational and could not prove that ultra-processed foods were causing dementia. Today, about 53 percent of all calories consumed by adults in the US come from ultra-processed foods. Among children, nearly 62 percent of calories consumed come from these foods. In the study, published in Alzheimer's and Dementia, participants got about 41 percent of their calories from processed food, which was about average for Australia.
The most common sources were dairy-based desserts and drinks, soft drinks, fruit juices, and other sugar-sweetened beverages. Others included packaged salty snacks and potato products, processed meat, and ready meals. Participants were interviewed between 2016 and 2023 about their diet and then asked to complete cognitive tests. Most were female, and they were 56 years old on average, but ranged in age from 40 to 70 years old. All lived in Australia. Researchers only interviewed the participants once and then used an analysis to establish the impact of eating more ultra-processed foods over time.
Cardoso added: 'Food ultra-processing often destroys the natural structure of food and introduces potentially harmful substances like artificial additives or processing chemicals. These additives suggest the link between diet and cognitive function extends beyond just missing out on foods known as healthy, pointing to mechanisms linked to the degree of food processing itself.'
The researchers did not find a link between ultra-processed food consumption and memory loss. They said this may be because areas of the brain linked to attention span and focus are more vulnerable to environmental stressors.
Broader Implications
Ultra-processed foods became ubiquitous in the US in the 1980s, around the same time that rates of obesity and chronic diseases started to rise. But they are a very broad category of foods that is poorly defined. There is no official definition in the US. While many studies have warned about their health risks, some experts have pushed back on warnings over them, saying that just because something is ultra-processed does not necessarily mean that it is bad for you. While some foods may be considered ultra-processed because of their ingredient count, some actually have lower levels of fats and salts—which may help lower the risk of heart conditions—and higher protein levels, which have been linked to better overall health.
Health and Human Services Secretary Robert F. Kennedy Jr. has urged Americans to eat fewer ultra-processed foods, and in a new food pyramid released by the FDA in January, health officials urged Americans to 'significantly limit' their consumption of the foods to boost their health.
