Eating ultraprocessed foods tied to a 58% higher risk of developing dementia

People who eat over two pounds of ultraprocessed foods like hot dogs and cookies a day are at a 58 percent increased risk of developing dementia and a 46 percent heightened risk for cognitive impairment, an alarming new study from researchers at Harvard’s T.H. Chan School of Public Health shows.

Dementia has long been a major problem in the U.S. — one that is projected to worsen in coming years. The chronic condition affects people’s memory, personality and behavior, devastating both patients and their loved ones.

There are more than 7.2 million Americans living with Alzheimer’s disease, which is the most common form of dementia. That number could be close to 13 million by 2050, the Alzheimer’s Association says.

The findings could help explain how America got here, and inform future steps experts recommend to reverse course.

Around 70 percent of the American diet has become ultraprocessed over the last half century, according to the National Institute of Health, as companies edited their products’ flavor, color and shelf life. The products were designed to be more "hyperpalatble" to consumers, featuring tempting combinations of salts, fats and sugars, Kansas University researchers say.

Since then, years of research has uncovered the harms of these foods, including similarly negative impacts on brain health, the heart, the immune system and other systems in the body.

It’s not just the major eaters that are at risk, too.

Even moderate levels of consumption were a problem for the brain, the new study found. That’s around a pound or less.

“Just to say, ‘well, I don’t eat all my calories from ultraprocessed foods, I’m safe.’ It really shows there may not be a safe level,” Cindy Leung, an associate professor of public health nutrition, told The Wall Street Journal.

The researchers analyzed the health of more than 5,300 older adults over the course of close to a decade. The participants were from the University of Michigan’s Health and Retirement Study, which includes health data gathered from approximately 20,000 Americans and is supported by the National Institute on Aging.

Participants were asked questions about their food intake, as well as smoking, alcohol use, activity level and other factors that affect brain and overall health.

Comparing the data revealed that people who ate processed meats had the highest risk of dementia and cognitive impairment, such as bacon and sliced ham.

But because the study’s data is self-reported, the researchers say they can’t actually prove ultraprocessed foods are the cause of dementia and cognitive decline.

Still, ultraprocessed foods are also tied to risk factors for dementia, such as obesity, gut changes and cardiovascular disease.

“[Ultraprocessed foods] have been associated with negative changes in the endocrine system and the gut microbiota, and these could lead to negative neurological outcomes,” Barbara Cardoso, a senior lecturer of nutrition dietetics and food at Australia’s Monash University, told CNN in April.

“Further, [they] have been linked to known cardiovascular risk factors for dementia, such as diabetes, hypertension, obesity and high LDL cholesterol, and as such could indirectly impact cognitive health,” she said.

Cardoso was the author of a study showing eating even one serving of ultraprocessed foods a day may raise the risk of dementia.

Her research followed a May 2025 study from Virginia Tech University that found people who ate at least one serving of ultraprocessed meat each day had a 17 percent increase in cognitive issues. Those who drank a serving of sugar-heavy soda had a six percent increase in cognitive impairment.

Fortunately, experts say people can reduce their risk by forgoing ultraprocessed foods.

People who ate the most minimally processed foods, like fruits and vegetables, had a 41 percent lower risk of dementia compared to others, the Harvard study found.

“There are things that you can change,” Brenda Davy, a professor of human nutrition, foods, and exercise at the school, said in a statement. “It’s moderation and being reasonable and balanced in your dietary choices.”