A recent study published in the American Journal of Public Health highlights a significant correlation between ultraprocessed food consumption and an increased risk of dementia. Researchers from the Harvard T.H. Chan School of Public Health examined data from 5,370 adults aged 50 and older participating in the Health and Retirement Study conducted by the University of Michigan. The participants, averaging 64 years old and comprising 55 percent women, had their diets assessed and classified by the degree of industrial processing, followed by tracking their health over approximately nine years from 2012 to 2020.
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Findings indicated that individuals consuming the highest amounts of ultraprocessed foods had a 58 percent greater risk of developing dementia and a 46 percent heightened risk of cognitive impairment not reaching dementia diagnosis. Conversely, those with the most minimalist diets consisting of whole grains, fruits, and vegetables saw a 41 percent reduction in dementia risk and a 24 percent reduction in cognitive impairment risk.
Among the various categories of ultraprocessed foods, processed meats, including bacon and deli meats, showed the strongest association with these adverse outcomes. However, the study did not establish causation; it only demonstrated a relationship between increased ultraprocessed food consumption and higher dementia diagnoses.
Researchers proposed indirect mechanisms, noting that ultraprocessed foods are frequently linked to obesity, cardiovascular disease, and type 2 diabetes—conditions known to be associated with dementia. Another speculation relates to additives in processed foods potentially altering gut bacteria, leading to chronic inflammation that could affect brain health. The specific reasons why processed meats stand out require further investigation.
Cindy Leung, the lead researcher, emphasized the possibility that there may not be a safe level of ultraprocessed food consumption. This statement reflects her interpretation of the data, rather than a specified threshold identified in the study. The authors of the study underline that while the association is clear, self-reported dietary data introduces variability, and heavy consumers of ultraprocessed foods may also differ in other health-related factors.
Overall, while the 58 percent increase in dementia risk linked to ultraprocessed foods is notable, the findings also stress the importance of diet quality, suggesting that foods added to a meal can be as impactful on health as those removed from it.
Study reference: Leung C, et al. Ultraprocessed food consumption and risk of cognitive impairment and dementia. American Journal of Public Health, June 2026.