Ultra-processed foods linked to memory and thinking problems: study

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It has long been a given that people who eat more ultra-processed foods — think soft drinks, chips and cookies — have a greater risk of physical side effects associated with that diet. Now a study has found that such foods are also associated with an elevated risk of memory and thinking problems.

The new paper published in Neurology, the medical journal of the American Academy of Neurology, stops short of claiming proof that eating ultra-processed foods causes memory and thinking problems and stroke. But it does show an association.

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For the study, researchers looked at more than 30,000 people age 45 or older. They were followed an average of 11 years. Participants filled out questionnaires about what they ate and drank. Researchers determined how much ultra-processed food people ate by calculating the grams per day and comparing it to the grams per day of other foods to create a percentage of their daily diet.

Ultra-processed foods are high in added sugar, fat and salt, and low in protein and fibre. They include soft drinks, salty and sugary snacks, ice cream, hamburgers, canned baked beans, ketchup, mayonnaise, packaged breads and flavoured cereals.

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

Of the total participants, researchers looked at 14,175 for cognitive decline and 20,243 for stroke. Neither group had a history of cognitive impairment or stroke. By the end of the study, 768 people were diagnosed with cognitive impairment and 1,108 people had a stroke.

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For those in the cognitive group, people who developed memory and thinking problems consumed 25.8 per cent of their diet in ultra-processed foods, compared to 24.6 per cent for those who did not develop cognitive problems.

After adjusting for age, sex, high blood pressure and other factors that could affect risk of dementia, researchers found that a 10 per cent increase in the amount of ultra-processed foods eaten was associated with a 16 per cent higher risk of cognitive impairment. They also found that eating more unprocessed or minimally processed foods was linked with a 12 per cent lower risk of cognitive impairment.

For those in the stroke group, people who had a stroke during the study consumed 25.4 per cent of their diet in ultra-processed foods, compared to 25.1 per cent for those who did not have a stroke.

After adjustments, researchers found greater intake of ultra-processed foods was linked to an 8 per cent increase in risk of stroke, while greater intake of unprocessed or minimally processed foods was linked to a 9 per cent decreased risk of stroke. The effect of ultra-processed food consumption on stroke risk was even greater among Black participants, with a 15 per cent relative increase in risk of stroke.

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“Our findings show that the degree of food processing plays an important role in overall brain health,” said study author W. Taylor Kimberly, MD, PhD, of Massachusetts General Hospital in Boston. “More research is needed to confirm these results and to better understand which food or processing components contribute most to these effects.”

A limitation of the study was that only participants who self-identified as Black or white were included in the study, so results may not be generalizable to people from other populations.

“While a healthy diet is important in maintaining brain health among older adults, the most important dietary choices for your brain remain unclear,” said Kimberly. “We found that increased consumption of ultra-processed foods was associated with a higher risk of both stroke and cognitive impairment, and the association between ultra-processed foods and stroke was greater among Black participants.”

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