A new study from Harvard's T.H. Chan School of Public Health has revealed a concerning link between ultraprocessed foods and brain health. People who consume more than two pounds of such foods daily—including hot dogs, cookies, and smoked meats—face a 58% increased risk of developing dementia and a 46% heightened risk for cognitive impairment.
Dementia Crisis in America
Dementia remains a major public health issue in the United States, with projections indicating it will worsen. Over 7.2 million Americans currently live with Alzheimer's disease, the most common form of dementia. The Alzheimer's Association warns this number could approach 13 million by 2050. The condition severely impacts memory, personality, and behavior, affecting both patients and their families.
Ultraprocessed Foods Dominate American Diets
According to the National Institute of Health, ultraprocessed foods now constitute about 70% of the average American diet—a dramatic increase over the past 50 years. Food manufacturers have engineered these products to be hyperpalatable, combining salts, fats, and sugars to enhance flavor, color, and shelf life. Researchers from Kansas University note that these combinations are designed to be irresistible to consumers.
The new findings build on years of research linking ultraprocessed foods to various health harms, including negative impacts on the brain, heart, and immune system. Notably, even moderate consumption poses risks. Cindy Leung, an associate professor of public health nutrition, told The Wall Street Journal, “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.”
Study Details and Findings
Researchers analyzed health data from over 5,300 older adults over nearly a decade, drawn from the University of Michigan's Health and Retirement Study, which includes approximately 20,000 Americans and is supported by the National Institute on Aging. Participants reported their food intake, smoking, alcohol use, activity levels, and other factors affecting brain and overall health.
The analysis revealed that processed meats—such as bacon and sliced ham—were associated with the highest risk of dementia and cognitive impairment. However, the study's self-reported data means researchers cannot definitively prove causation. Nonetheless, ultraprocessed foods are linked to known dementia risk factors, including obesity, gut microbiome changes, and cardiovascular disease.
Barbara Cardoso, a senior lecturer at Monash University in Australia, explained to CNN that ultraprocessed foods have been associated with negative changes in the endocrine system and gut microbiota, potentially leading to adverse neurological outcomes. She also noted their connection to cardiovascular risk factors like diabetes, hypertension, obesity, and high LDL cholesterol.
Previous Research and Expert Advice
Cardoso authored a study showing that even one serving of ultraprocessed foods daily may raise dementia risk. Another study from Virginia Tech University in May 2025 found that consuming at least one serving of ultraprocessed meat daily led to a 17% increase in cognitive issues, while a serving of sugary soda correlated with a 6% increase.
Fortunately, dietary changes can reduce risk. The Harvard study found that individuals who ate the most minimally processed foods—such as fruits and vegetables—had a 41% lower dementia risk compared to others. Brenda Davy, a professor of human nutrition at Virginia Tech, emphasized, “There are things that you can change. It’s moderation and being reasonable and balanced in your dietary choices.”
