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Consuming highly processed foods may harm the aging brain, increasing the risk of cognitive decline and stroke, according to new research. The study, which followed a large cohort of adults for over 10 years, suggests that eating more ultraprocessed foods (UPFs) raises these risks, while a diet rich in unprocessed or minimally processed foods may offer protective benefits.
Key Findings and Insights
“The first key takeaway is that the type of food we eat matters for brain health, but it’s equally important to think about how it’s made and handled,” said Dr. W. Taylor Kimberly, MD, PhD, from Massachusetts General Hospital, Boston. “The second is that it’s not just all bad news. While increased consumption of ultra-processed foods is linked to a higher risk of cognitive impairment and stroke, unprocessed foods appear to be protective.”
Published online on May 22 in Neurology, the study underscores the potential impact of food processing on brain health. UPFs, which include items like soft drinks, chips, and sweetened cereals, are low in protein and fiber but high in added sugars, fats, and salts. Conversely, unprocessed or minimally processed foods, such as fresh meats and vegetables, were found to be beneficial.
Study Design and Results
The researchers used data from the long-running REGARDS study, a large U.S. cohort of Black and White adults aged 45 years and older. They categorized food processing levels using the NOVA food classification system, from unprocessed (NOVA1) to highly processed (NOVA4), and assessed dietary patterns through food frequency questionnaires.
In the cognitive impairment cohort, 768 out of 14,175 adults developed cognitive impairment. A 10% increase in UPF intake was linked to a 16% higher risk of cognitive impairment, while higher intake of unprocessed foods was associated with a 12% lower risk.
In the stroke cohort, 1,108 out of 20,243 adults experienced a stroke. Greater UPF consumption was associated with an 8% increased stroke risk, while unprocessed foods were linked to a 9% lower risk. The impact of UPFs on stroke risk was notably greater among Black adults.
Implications for Dietary Guidelines
The study’s findings were independent of adherence to traditional healthy dietary patterns, such as the Mediterranean and DASH diets. This suggests that food processing levels may play a significant role in brain health outcomes beyond general dietary guidelines.
The accompanying editorial by Peipei Gao, MS, and Zhendong Mei, PhD, from Harvard, highlights the robust nature of the results and their implications for public health. They point out that the detrimental effects of UPFs may be due to poor nutrient profiles and the presence of additives that disrupt gut health and promote inflammation.
Future Directions
Dr. Kimberly emphasized that the study’s observational nature means it cannot definitively prove that substituting UPFs with unprocessed foods will improve brain health, a question that requires clinical trials. The editorialists called for further large-scale studies and mechanistic research to identify specific harmful components and processes in UPFs.
The study received funding from the National Institute of Neurological Disorders and Stroke, the National Institute on Aging, the National Institutes of Health, and the Department of Health and Human Services. The authors and editorialists reported no relevant disclosures.
As evidence mounts on the risks associated with UPFs, this research may inform future dietary guidelines and public health policies aimed at preserving brain health.
