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Child Psychiatrist /Adult Psychiatrist

Ultraprocessed Foods an Independent Risk Factor for Poor Brain Health

Consuming highly processed foods may be harmful to the aging brain, independent of other risk factors for adverse neurologic outcomes and adherence to recommended dietary patterns, new research suggests.


Poor Brain Health

Observations from a large cohort of adults followed for more than 10 years suggested that eating more ultraprocessed foods (UPFs) may increase the risk for cognitive decline and stroke, while eating more unprocessed or minimally processed foods may lower the risk.


"The first key takeaway is that the type of food that we eat matters for brain health, but it's equally important to think about how it's made and handled when thinking about brain health," study investigator W. Taylor Kimberly, MD, PhD, with Massachusetts General Hospital in Boston, told Medscape Medical News.


"The second is that it's not just all a bad news story because while increased consumption of ultra-processed foods is associated with a higher risk of cognitive impairment and stroke, unprocessed foods appear to be protective," Kimberly added.


The study was published online on May 22 in Neurology.


Food Processing Matters


UPFs are highly manipulated, low in protein and fiber, and packed with added ingredients, including sugar, fat, and salt. Examples of UPFs are soft drinks, chips, chocolate, candy, ice cream, sweetened breakfast cereals, packaged soups, chicken nuggets, hotdogs, and fries.


Unprocessed or minimally processed foods include meats such as simple cuts of beef, pork and chicken, and vegetables and fruits.


Research has shown associations between high UPF consumption and increased risk for metabolic and neurologic disorders.


As reported previously by Medscape Medical News, in the ELSA-Brasil, higher intake of UPFs was significantly associated with a faster rate of decline in executive and global cognitive function.


Yet, it's unclear whether the extent of food processing contributes to the risk of adverse neurologic outcomes independent of dietary patterns.


Kimberly and colleagues examined the association of food processing levels with the risk for cognitive impairment and stroke in the long-running REGARDS study, a large prospective US cohort of Black and White adults aged 45 years and older.


Food processing levels were defined by the NOVA food classification system, which ranges from unprocessed or minimally processed foods (NOVA1) to UPFs (NOVA4). Dietary patterns were characterized based on food frequency questionnaires.


In the cognitive impairment cohort, 768 of 14,175 adults without evidence of impairment at baseline who underwent follow-up testing developed cognitive impairment.


Diet an Opportunity to Protect Brain Health


In multivariable Cox proportional hazards models adjusting for age, sex, high blood pressure, and other factors, a 10% increase in relative intake of UPFs was associated with a 16% higher risk for cognitive impairment (hazard ratio [HR], 1.16). Conversely, a higher intake of unprocessed or minimally processed foods correlated with a 12% lower risk for cognitive impairment (HR, 0.88).


In the stroke cohort, 1108 of 20,243 adults without a history of stroke had a stroke during the follow-up.


In multivariable Cox models, greater intake of UPFs was associated with an 8% increased risk for stroke (HR, 1.08), while greater intake of unprocessed or minimally processed foods correlated with a 9% lower risk for stroke (HR, 0.91).


The effect of UPFs on stroke risk was greater among Black than among White adults (UPF-by-race interaction HR, 1.15).


The associations between UPFs and both cognitive impairment and stroke were independent of adherence to the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, and the Mediterranean-DASH Intervention for Neurodegenerative Delay diet.


These results "highlight the possibility that we have the capacity to maintain our brain health and prevent poor brain health outcomes by focusing on unprocessed foods in the long term," Kimberly said.


He cautioned that this was "an observational study and not an interventional study, so we can't say with certainty that substituting ultra-processed foods with unprocessed foods will definitively improve brain health," Kimberly said. "That's a clinical trial question that has not been done but our results certainly are provocative."


Consider UPFs in National Guidelines?


The coauthors of an accompanying editorial said the "robust" results from Kimberly and colleagues highlight the "significant role of food processing levels and their relationship with adverse neurologic outcomes, independent of conventional dietary patterns."


Peipei Gao, MS, with Harvard T.H. Chan School of Public Health, and Zhendong Mei, PhD, with Harvard Medical School, both in Boston, noted that the mechanisms underlying the impact of UPFs on adverse neurologic outcomes "can be attributed not only to their nutritional profiles," including poor nutrient composition and high glycemic load, "but also to the presence of additives including emulsifiers, colorants, sweeteners, and nitrates/nitrites, which have been associated with disruptions in the gut microbial ecosystem and inflammation."


"Understanding how food processing levels are associated with human health offers a fresh take on the saying 'you are what you eat,'" wrote Gao and Mei.


This new study, they noted, adds to the evidence by highlighting the link between UPFs and brain health, independent of traditional dietary patterns and "raises questions about whether considerations of UPFs should be included in dietary guidelines, as well as national and global public health policies for improving brain health."


The editorialists called for large prospective population studies and randomized controlled trials to better understand the link between UPF consumption and brain health. "In addition, mechanistic studies are warranted to identify specific foods, detrimental processes, and additives that play a role in UPFs and their association with neurologic disorders," the editorialists concluded.


Note: This article originally appeared on Medscape

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