Eating more ultraprocessed foods is linked to a higher risk of cognitive decline and stroke, even if a person is trying to adhere to a Mediterranean diet, the DASH diet or the MIND diet, a new study found.
All three diets are plant-based, focused on consuming more fruits and vegetables, whole grains, beans and seeds while limiting sugar, red meat and ultraprocessed foods.
“If you increased your ultraprocessed food intake by 10 per cent in the study, it increased your risk of cognitive impairment by 16 per cent,” said cardiologist Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver. He was not involved in the study.
“You can always extrapolate and say, ‘Well, if someone increases their ultraprocessed food consumption by 100 per cent, then they have 160 per cent chance of cognitive impairment,’” he said. “Of course, this study can only show an association, not a direct cause and effect.”
On the flip side, eating more unprocessed or minimally processed foods was linked with a 12 per cent lower risk of cognitive impairment, according to the study published Wednesday in the journal Neurology.
Unprocessed foods include fresh fruits and vegetables, eggs and milk. Minimally processed foods include culinary ingredients such as salt, herbs and oils and foods such as canned goods and frozen vegetables that combine culinary ingredients with unprocessed foods.
Ultraprocessed foods include prepackaged soups, sauces, frozen pizza, ready-to-eat meals and pleasure foods such as hot dogs, sausages, French fries, sodas, store-bought cookies, cakes, candies, doughnuts, ice cream and many more.
Such foods are typically high in calories, added sugar and salt and low in fibre, all of which can contribute to cardiometabolic health problems, weight gain, obesity, Type 2 diabetes and high blood pressure, experts say.
An increased risk of stroke
The study analyzed data on 30,000 people participating in the REGARD, or REasons for Geographic and Racial Differences in Stroke study, made up of 50 per cent Whites and 50 per cent Blacks in a nationally diverse group of people who have been followed for up to 20 years.
The risk of stroke was 8 per cent higher for people who added the most ultraprocessed foods to their diet as compared with those who ate minimally processed foods, said study author and neurologist Dr. W. Taylor Kimberly, chief of the division of neurocritical care at Massachusetts General Hospital in Boston.
That risk rose to 15 per cent for Black participants, likely due to the impact of ultraprocessed foods on high blood pressure in that population, Kimberly said. However, if a person ate more unprocessed or minimally processed foods, the risk of stroke dropped by 9 per cent, the study found.
What is it about ultraprocessed foods that may allow them to sabotage efforts to follow a healthy diet? It could be their poor nutrient composition and tendency to spike blood sugars, which can lead to Type 2 diabetes, obesity, elevated blood pressure and high cholesterol, said Peipei Gao and Zhendong Mei in an editorial published with the study.
Mei is a research fellow in medicine at Brigham and Women’s Hospital in Boston, while Gao is a graduate student in nutrition visiting Harvard T.H. Chan School of Public Health, also in Boston. Neither was involved in the study.
Type 2 diabetes, obesity, elevated blood pressure and high cholesterol are all key risk factors for vascular disease in the heart and brain, they wrote.
The impact on blood vessels that leads to stroke and cognitive decline may also be due “to the presence of additives including emulsifiers, colourants, sweeteners, and nitrates/nitrites, which have been associated with disruptions in the gut microbial ecosystem and inflammation,” they added.
Growing dangers of ultraprocessed foods
Studies on the dangers of eating ultraprocessed foods are piling up. According to a February review of 45 meta-analyses on almost 10 million people, eating 10 per cent more ultraprocessed foods raised the risk of developing or dying from dozens of adverse health conditions.
That 10 per cent increase was considered “baseline,” and adding even more ultraprocessed foods might increase the risk, experts say.
There was strong evidence that a higher intake of ultraprocessed foods was associated with about a 50 per cent higher risk of cardiovascular disease-related death and common mental disorders, according to the review.
Researchers also found highly suggestive evidence that eating more ultraprocessed foods raised the risk of obesity by 55 per cent, sleep disorders by 41 per cent, development of Type 2 diabetes by 40 per cent and the risk of depression by 20 per cent.
“We really need to put a sign in the ultraprocessed food section, or on the packaging like they do on cigarettes, saying, ‘Warning, this food may be detrimental to your health,’” Freeman said.
“What we think of as ‘convenient food’ really needs to change from a package of chips to an apple or carrot that is also shelf-stable and can travel in your purse or backpack,” he said. “And we need to make that kind of stuff more readily available, especially to our kids and in food deserts where often all the available food is ultraprocessed.”