Recent research published in American Journal of Public Health This suggests that older people who consume large amounts of ultra-processed foods are at increased risk of developing dementia and other forms of cognitive decline. The findings provide evidence that replacing industrially produced foods with fresh, unprocessed alternatives tends to provide protective benefits for maintaining brain health later in life.
Ultra-processed foods are products produced in industrial settings that contain chemical additives, artificial flavors, and preservatives. These ingredients are designed to make the product taste better and stay on store shelves longer. Examples include sugary sodas, packaged sugary snacks, sugary breakfast cereals, and mass-produced frozen foods. These foods tend to be high in sugar, sodium, and saturated fat, while lacking in important dietary fiber.
In the United States, these highly processed items make up a large portion of many adults’ daily caloric intake. Its convenience and wide availability has led to increased consumption, especially among the elderly. High intakes of these foods have already been linked to physical health conditions such as obesity, diabetes, and heart disease.
In recent years, scientists have focused on the potential effects of highly processed diets on the human brain. There is some evidence to suggest that poor diet quality plays a role in cognitive decline, but past studies have yielded mixed results when it comes to mild cognitive problems. In fact, a previous American longitudinal study found no significant association between ultra-processed diets and general cognitive impairment.
However, previous studies did not measure food intake by body weight. This method is often a more accurate way to understand how much of a person’s diet consists of these items. The authors of a new paper sought to fill this gap in the literature. They wanted to investigate how eating huge amounts of ultra-processed foods was associated with certain health effects, such as full-blown dementia and mild cognitive impairment.
To explore this relationship, researchers analyzed data from the Health and Retirement Study. This is a large, nationally representative longitudinal study of older Americans. The final sample included 5,370 adults aged 50 and older. To ensure they were looking at new cases of cognitive decline, the scientists excluded people who already had a diagnosis of dementia or memory problems at the start of the data collection period.
Participants completed a detailed food frequency questionnaire in 2013, reporting how often they ate various items in the previous year. The researchers then categorized these foods based on their level of industrial processing. They calculated the proportion of each person’s total daily diet that came from ultra-processed foods, and adjusted the measurements by weight in grams, rather than simply counting daily calorie intake.
Scientists have divided ultra-processed products into 13 mutually exclusive subgroups. These categories include whole grains, dairy products, fats and oils, processed meats, snacks and sweets, and sugar-sweetened beverages. Ultimately, sugary drinks and other beverages contributed the most to participants’ total ultra-processed food intake.
To track brain health, participants underwent cognitive assessments every two years from 2014 to 2020. These tests included tasks such as counting backwards, recalling lists of words immediately or delayed, and subtracting a series of numbers. Based on a 27-point scoring system, participants were classified as having normal cognitive function, cognitive impairment without dementia, or complete dementia.
Cognitive impairment without dementia refers to a marked decline in mental abilities, such as memory and thinking, that is not severe enough to completely interfere with daily life. People with this condition are at increased risk of eventually developing full-blown dementia. The researchers used a composite category that combined both of these conditions as part of their statistical analysis.
The researchers followed the participants for an average of nearly nine years. During that time, 266 new cases of dementia, 1,191 cases of non-dementia cognitive impairment, and 1,310 cases of combined category were identified. They then compared the cognitive outcomes of those who ate the most ultra-processed foods to those who ate the least.
Adults in the top fifth of ultra-processed food intake had a 58 percent higher risk of developing dementia than those in the bottom fifth. They also found that the most expensive consumers had a 46% higher risk of developing cognitive impairment without dementia. Researchers observed these increased risks even after adjusting for factors such as age, gender, race, education, wealth, physical activity, and smoking habits.
When analyzing specific types of ultra-processed items, the authors found that processed meat was the only individual category significantly associated with higher risk across all cognitive outcomes. Unprocessed or minimally processed foods, such as fresh fruits, vegetables, and plain grains, showed exactly the opposite pattern. Higher intakes of these natural foods were found to significantly reduce the risk of both dementia and mild cognitive impairment.
Scientists also investigated whether social factors influenced this relationship. Researchers created a social isolation score based on whether participants lived alone, were unmarried, or had little contact with friends, family, or social clubs. The association between poor diet and cognitive impairment tends to be stronger among older people who have experienced social isolation, suggesting that this population may be particularly vulnerable.
Although this study provides extensive evidence linking diet and brain health, it also has some limitations. Dietary questionnaires rely on participants remembering and reporting their eating habits, which can sometimes lead to unintended inaccuracies. Because the study was not explicitly designed to track industrial food processing, the researchers may have underestimated the true amount of ultra-processed foods people consume on a daily basis.
Furthermore, the cognitive results were based on a questionnaire-based psychological test rather than a formal clinical diagnosis by a neurologist. Although these tests are widely used and validated in population studies, they can misclassify a person’s true cognitive status in some cases. This study design also leaves open the possibility that unmeasured lifestyle factors may subtly influence both dietary choices and brain health over time.
It’s also possible that early, undetected brain changes influence eating habits before formal cognitive problems are recognized. People experiencing early memory loss may transition to eating more convenient packaged meals out of necessity. The researchers attempted to explain this by excluding individuals who developed cognitive impairment within the first two years of the study, but reverse causation may still exist.
The biological reasons behind these findings require further investigation. The authors suggest that consuming large amounts of industrial additives and sugar can alter gut bacteria, increase oxidative stress, and promote chronic inflammation in the body. These physical reactions could theoretically disrupt biological pathways that maintain healthy brain tissue and support cognitive function.
Future studies may focus on longer follow-up periods and more accurate food recording methods, such as daily food diaries. Health professionals may be able to use this growing body of evidence to encourage older adults to prioritize fresh foods in their daily lives. Public health policies may also support these individual choices by making minimally processed foods more available and affordable in communities.
The study, “Ultra-processed foods and the risk of cognitive impairment and dementia in older Americans: The 2013-2020 Health and Retirement Study,” was co-authored by Heejin Lee, Claire T. McEvoy, Euridice Martinez Steele, Neha Khandpur, Steven G. Heeringa, Lindsay H. Ryan, Kenneth M. Langa, Julia A. Wolfson, and Cindy W. Leung.
