A recent study has found that eating large amounts of ultra-processed foods may speed up memory loss and decline in thinking skills as people age. These foods, which include things like soft drinks, packaged snacks, frozen meals, and fast food, are often high in sugars, unhealthy fats, and additives—and low in nutrients the brain needs to stay healthy.
Ultra-processed foods are made mostly from substances extracted from whole foods. These ingredients include added sugars, refined starches, oils, and artificial additives such as colors, flavors, and preservatives.
While convenient and tasty, these foods lack the fiber, vitamins, and healthy fats found in fresh, whole foods. Common examples include hot dogs, chips, instant noodles, sweetened breakfast cereals, and sugary desserts.
Earlier studies have already linked these foods to a higher risk of obesity, heart disease, cancer, and early death. Now, scientists are turning their attention to how they may affect the brain.
In this new study, researchers followed 10,775 adults in Brazil for up to 10 years. The participants were part of a large health study looking at long-term changes in physical and mental health. The researchers found that those who ate the most ultra-processed food showed signs of cognitive decline much faster than those who ate the least.
Specifically, people who got more than 20% of their daily calories from these foods had a 28% faster decline in general thinking ability and a 25% faster decline in executive function, which includes skills like planning, decision-making, and self-control.
To put that into perspective, if someone eats a 2,000-calorie diet—a common daily recommendation—getting just 400 of those calories from ultra-processed foods could be enough to increase their risk. That’s roughly the number of calories in a soft drink, a bag of chips, and a small fast-food burger.
Researchers stress that this study shows a connection, not direct proof that ultra-processed foods cause brain decline. However, the results support earlier evidence suggesting that poor diet can affect brain health over time.
One concern is that ultra-processed foods are now a huge part of many people’s diets. In the U.S., for example, nearly 60% of all calories people eat come from these kinds of foods. They also provide almost 90% of the added sugars in the average American diet.
The brain, like the rest of the body, needs proper fuel to function well. A diet high in added sugars, unhealthy fats, and chemical additives may lead to long-term inflammation, poor blood flow, and damage to brain cells. This can, over time, affect memory and thinking abilities.
Dr. David Katz and his team, who conducted the study, say their findings are a warning sign. Although more research is needed to understand exactly how these foods may harm the brain, making healthier food choices—like eating more vegetables, fruits, whole grains, nuts, and lean proteins—may help protect brain health as we age.
The study was published in JAMA Neurology, a leading medical journal focused on brain health.
If you care about dementia, please read studies that eating apples and tea could keep dementia at bay, and Olive oil: a daily dose for better brain health.
For more health information, please see recent studies what you eat together may affect your dementia risk, and time-restricted eating: a simple way to fight aging and cancer.
Copyright © 2025 Knowridge Science Report. All rights reserved.
