Ultra-processed foods could be increasing our risk of cognitive problems and strokes, a study has found, adding to the growing body of evidence that what we eat can affect our brain function.
In the U.S., ultra-processed foods account for almost 60 percent of our energy intake, according to research published in The BMJ. This includes a range of packaged snacks, carbonated drinks, instant noodles, ready meals and most products that contain a long list of unrecognizable ingredients, preservatives, emulsifiers, sweeteners and artificial flavorings.
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A growing body of research has linked ultra-processed foods to an increased risk of various diseases, such as heart disease, diabetes, bowel cancer and obesity. Now, new research from Massachusetts General Hospital has found a link between ultra-processed foods and brain health.
"Several independent studies have shown associations between ultra-processed foods and important health outcomes," study author and Harvard neurology professor W. Taylor Kimberly told Newsweek.
"Our study adds to this work by showing that UPFs are associated with two major contributors to impaired brain function—stroke and cognitive impairment," he continued. "Our study also shows that it's important to pay attention to not just what foods we eat but how those foods are processed before we eat them."
The research, published in the journal Neurology, examined data from 30,239 participants 45 or older who were followed over an average period of 11 years. The participants were asked to fill out questionnaires on what they ate and drank, from which the team calculated their average daily intake of ultra-processed food.
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Among these participants, 14,175 were investigated for signs of cognitive decline, while 20,243 were investigated for strokes. No one in either group had a history of cognitive decline or stroke before the start of the study period. By the end of the study, 768 participants had been diagnosed with cognitive impairment, and 1,108 had had a stroke.
After adjusting for age, sex, high blood pressure and other known dementia risk factors, the team found that a 10 percent increase in ultra-processed food intake was associated with a 16 percent higher risk of cognitive impairment. Conversely, eating unprocessed and minimally processed foods was associated with a 12 percent lower risk of cognitive impairment.
After the team adjusted for the same risk factors, stroke risk was 8 percent higher among those with a greater intake of ultra-processed foods, while minimally processed foods were associated with a 9 percent lower risk of stroke.
This effect was particularly pronounced among Black participants. Ultra-processed food consumption was associated with a 15 percent increased risk of stroke for this demographic.
"Our findings show that the degree of food processing plays an important role in overall brain health," Kimberly said. "More research is needed to confirm these results and to better understand which food or processing components contribute most to these effects.... These results are associations, so it will be important to evaluate in a randomized trial how making changes to our diet changes the risk of these health outcomes."
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While this study did not investigate the causal effects behind these associations, Kimberly said that the trillions of microbes that live in our guts, and the molecules they produce, likely play a significant role.
"We've been very interested to understand how the food we eat affects metabolites that are measurable in the bloodstream," he said. "The food we eat is metabolized and transformed by the bacteria in our gut. What's interesting to us is that some of the metabolites linked to stroke and/or cognitive impairment are linked to specific food types and are synthesized by the gut microbiome. It therefore stands to reason that ultra-processed foods may also impact our gut microbiome, which in turn could impact long-term brain health."
When it comes to stroke risk, ultra-processed foods may have both direct and indirect effects.
"Other studies have shown that ultra-processed foods are associated with high blood pressure, diabetes and cardiovascular disease," Kimberly said. "These medical conditions also increase the risk of future stroke. Therefore, we believe that ultra-processed foods impact our stroke risk both directly, through impacting cerebrovascular health, and indirectly, through high blood pressure, diabetes and heart disease."
Kimberly said that while the team's findings were purely observational, they add to a growing body of research that shows reducing consumption of ultra-processed foods is likely to benefit both your brain and overall health.
"Our study provides a reason to be mindful of the food we eat," he said. "Not only should we aim to increase the amount of healthy foods, such as leafy greens, nuts and fish-based protein, but we should also aim to reduce the amount of prepackaged foods and sweet and salty snacks."
However, it's also important to be practical and pragmatic, Kimberly said.
"Ultra-processed foods are convenient. They tend to have a longer shelf life and are designed to appeal to our sense of taste. The good news is that our study showed that even incrementally lower ultra-processed food consumption was associated with a better brain health profile," he said.
You can read the full study in Neurology, the American Academy of Neurology's medical journal.
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