(CNN) — We all eat them: ultra-processed foods like frozen pizza and precooked pizza make our lives easier. Plus, they’re delicious: who doesn’t like hot dogshot dogs, hamburgers, French fries, sodas, cookies, cakes, candy, donuts, and ice cream, just to name a few?
However, if more than 20% of your daily calorie intake comes from ultra-processed foods, your risk of cognitive decline may be increased, according to a new study.
The part of the brain involved in executive functioning ––the ability to process information and make decisions–– is especially affected, according to the study published Monday in the academic journal JAMA Neurology.
The men and women in the study who ate the most ultra-processed foods had a 25% faster rate of decline in executive function and a 28% faster rate of overall cognitive decline compared with those who ate the fewest. overly processed foods.
“Although this is an association study, not designed to prove cause and effect, there are a number of elements that support the idea that some acceleration of cognitive decline can be attributed to ultra-processed foods,” says Dr. David Katz , a specialist in preventive and lifestyle medicine and nutrition, who was not involved in the study.
“The sample size is large and the follow-up extensive. Although the evidence is lacking, it is strong enough to conclude that ultra-processed foods are probably bad for the brain.”
However, there was an interesting twist. If the quality of the overall diet was high, meaning the person also ate plenty of unprocessed fruits and vegetables, whole grains and healthy sources of protein, the association between ultra-processed foods and cognitive decline disappeared, Katz said.
“Ultra-processed foods drag diet quality down, and therefore their concentration in the diet is an indicator of poor diet quality in most cases,” Katz said. “Atypical as it may seem, some of the participants apparently managed to manage it. And when diet quality was high, the observed association between ultra-processed foods and brain function disappeared.”
Many ultra-processed foods
The study followed more than 10,000 Brazilians for 10 years. Slightly more than half of the study participants were female, white or college educated, while the median age was 51.
Cognitive tests, including immediate and delayed word recall, word recognition, and verbal fluency, were administered at the beginning and end of the study, and participants were asked about their diet.
“In Brazil, ultra-processed foods represent between 25% and 30% of total caloric intake. We have McDonald’s, Burger King, and we eat a lot of chocolate and white bread. It’s not very different, unfortunately, from many other Western countries” , co-author Dr. Claudia Suemoto, an associate professor in the division of geriatrics at the University of São Paulo School of Medicine, told CNN when the study abstract was published in August.
“58% of the calories consumed by US citizens, 56.8% of the calories consumed by British citizens and 48% of the calories consumed by Canadians come from ultra-processed foods,” Suemoto said.
According to the study, ultra-processed foods are defined as “industrial formulations of food substances (oils, fats, sugars, starch, and isolated proteins) that contain little or no whole foods and often include flavorings, colors, emulsifiers, and other cosmetic additives.”
Study participants who consumed more ultra-processed foods were “more likely to be younger, female, white, more educated and income, and more likely to have never smoked, and less likely to be regular alcohol consumers,” according to the study. study.
It’s not just the brain
“Ultra-processed foods in general are bad for all of our parts,” says Katz, president and founder of the nonprofit organization True Health Initiativea global coalition of experts dedicated to evidence-based lifestyle medicine.
Ultra-processed foods are often high in sugar, salt and fat, all of which promote inflammation throughout the body, which is “perhaps the biggest threat to healthy aging of the body and brain,” says Dr. Rudy Tanzi , professor of neurology at Harvard Medical School and director of the genetics and aging research unit at Massachusetts General Hospital in Boston. He did not participate in the study.
“Meanwhile, because they are convenient as fast food, they also replace the consumption of foods rich in plant fiber, which is important for maintaining the health and balance of the trillions of bacteria in the gut microbiome,” Tanzi added, “which is particularly important for brain health and to reduce the risk of age-related brain diseases, such as Alzheimer’s disease.
How can you prevent this from happening to you? If you include ultra-processed foods in your diet, try to counteract them by also eating high-quality foods, such as fruits, vegetables, and whole grains.
“The conclusion suggested here is that ultra-processed foods are indeed an important ‘ingredient’, but the exposure that public health efforts should focus on is the overall quality of the diet,” Katz says.
A simple way to ensure the quality of the diet is to cook and prepare food from scratch, according to Suemoto.
“We say we don’t have time, but it really doesn’t take that long,” Suemoto said.
“And it’s worth it, because you’ll be protecting your heart and brain from dementia and Alzheimer’s. That’s the message to take home: stop buying super-processed stuff.”