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Ultra-processed food linked to cognitive decline – Brazilian study

Consuming ultra-processed foods for more than 20% of your calorie intake every day could set you on the road to cognitive decline, a study has proved, affecting your ability to make decisions, process information and possibly hastening diseases like Alzheimer’s.

We all know eating ultra-processed foods that make our lives easier, like prepackaged soups, sauces, frozen pizza, instant meals, and so on, isn’t good for our health. Nor is gobbling up all the pleasure foods that we love so much: hot dogs, sausages, burgers, cooked chips, cold drinks, biscuits, cakes and ice cream, to name just a few.

Studies have found they can raise our risk of obesity, heart and circulation problems, diabetes and cancer. They may even shorten our lives.

Now, a recent, still to be peer reviewed, study, has revealed eating more ultra-processed foods may contribute to overall cognitive decline, including the areas of the brain involved in executive functioning – the ability to process information and make decisions, reports CNN.

In fact, men and women who ate the most ultra-processed foods had a 28% faster rate of global cognitive decline and a 25% faster rate of executive function decline compared with people who ate the least amount of overly processed food, the research found.

The study, presented recently at the 2022 Alzheimer’s Association International Conference in San Diego (31 July-4 August), followed more than 10,000 Brazilians for up to 10 years. Just over half of the study participants were women, white or college educated, while the average age was 51.

Cognitive testing, which included immediate and delayed word recall, word recognition and verbal fluency, was performed at the beginning and end of the study, and participants were asked about their diet.

“In Brazil, ultra-processed foods make up 25% to 30% of total calorie 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,” said co-author Dr Claudia Suemoto, an assistant professor in the division of geriatrics at the University of São Paulo Medical School.

“Fifty-eight percent of the calories consumed by United States citizens, 56.8% of the calories consumed by British citizens, and 48% of the calories consumed by Canadians come from ultra-processed foods,” she said.

Ultra-processed foods are defined as “industrial formulations of food substances (oils, fats, sugars, starch and protein isolates) that contain little or no whole foods and typically include flavourings, colourings, emulsifiers and other cosmetic additives”, according to the study.

“People who consumed more than 20% of daily calories from processed foods had a 28% faster decline in global cognition and a 25% faster decline in executive functioning compared to people who ate less than 20%,” said study co-author Natalia Gonçalves, a researcher in the department of pathology at the University of São Paulo Medical School.

For a person who eats 2,000 calories a day, 20% would equal 400 or more calories – for comparison, a small order of French fries and regular cheeseburger from McDonald’s contains a total of 530 calories.

Those in the study who ate the most ultra-processed foods were “likelier to be younger, women, white, with higher education and income, and more likely to have never smoked, and less likely to be current alcohol consumers”, the study found.

“People need to know they should cook more and prepare their own food from scratch. I know. We say we don’t have time but it really doesn’t take that much time,” Suemoto said.

“And it’s worth it because you’re going to protect your heart and guard your brain from dementia or Alzheimer’s disease,” she added. “That’s the take-home message: Stop buying things that are super-processed.”

To investigate, Goncalves and colleagues evaluated longitudinal data on 10,775 adults (mean age, 50.6 years; 56% women; 55% white) who participated in the ELSA-Brasil study. They were evaluated in three waves (2008–2010, 2012–2014, and 2017–2019).

Information on diet was obtained via food frequency questionnaires and included information regarding consumption of unprocessed foods, minimally processed foods, and UPFs (ultra-processsed foods).

Participants were grouped according to UPF consumption quartiles (lowest to highest). Cognitive performance was evaluated using a standardised battery of tests.

Significant decline

Using linear mixed effects models that were adjusted for sociodemographic, lifestyle and clinical variables, the investigators assessed the association of dietary UPFs as a percentage of total daily calories with cognitive performance over time.

During a median follow-up of eight years, UPF intake in quartiles two to four (vs quartile one) was associated with a significant decline in global cognition (P = .003) and executive function (P = .015).

“Participants who reported consumption of more than 20% of daily calories from ultra-processed foods had a 28% faster rate of global cognitive decline and a 25% faster decrease of the executive function compared to those who reported eating less than 20% of daily calories from ultra-processed foods,” Goncalves told Medscape.

“Considering a person who eats a total of 2 000 kcal a day, 20% of daily calories from ultra-processed foods are about two 1.5 bars of KitKat, or five slices of bread, or about a third of a packet of chips.”

Goncalves said the reasons UPFs may harm the brain remain a “very relevant but not yet well-studied topic”.

Hypotheses include secondary effects from cerebrovascular lesions or chronic inflammation processes. More studies are needed to investigate the possible mechanisms that might explain the harm of UPFs to the brain, she said.

Troubling but not surprising

Commenting on the study, Percy Griffin, PhD, director of scientific engagement for the Alzheimer’s Association, said there was “growing evidence that what we eat can have an impact our brains as we age”.

He said many previous studies have suggested it was best for the brain to eat a heart-healthy, balanced diet low in processed foods and high in whole, nutritional foods, such as vegetables and fruits.

“These new data suggest eating a large amount of ultra-processed food can significantly accelerate cognitive decline,” said Griffin, who was not involved with the research.

He noted that an increase in the availability and consumption of fast foods, processed foods, and UPFs is due to a number of socioeconomic factors, including low access to healthy foods, less time to prepare foods from scratch, and an inability to afford whole foods.

“Ultra-processed foods make up more than half of American diets. It’s troubling but not surprising to see new data suggesting these foods can significantly accelerate cognitive decline,” he said.

“The good news is we can reduce risk of cognitive decline as we age, like eating a balanced diet, exercising regularly, getting good sleep, staying cognitively engaged, protecting from head injury, not smoking, and managing heart health.”

Past research has suggested that the greatest benefit is from engaging in combinations of these lifestyle changes and that they are beneficial at any age, he noted.

“While in need of further study and replication, the new results are quite compelling and emphasise the critical role for proper nutrition in preserving and promoting brain health and reducing risk for brain diseases as we get older,” said Rudy Tanzi, professor of neurology at Harvard Medical School and director of the genetics and ageing research unit at Massachusetts General Hospital in Boston, who was not involved in the study.

Tanzi said the key problem with ultra-processed foods is that “they are usually very high in sugar, salt and fat, all of which promote systemic inflammation, perhaps the most major threat to healthy ageing in the body and brain.

“Meanwhile, since they are convenient as a quick meal, they also replace eating food that is high in plant fibre, which is important for maintaining the health and balance of the trillions of bacteria in your gut microbiome,” he added, “and which is particularly important for brain health and reducing risk of age-related brain diseases like Alzheimer’s disease.”

Alzheimer’s Association International Conference (AAIC) 2022: Abstract 63301. Presented 1 August 2022.

 

CNN article – Cognitive decline linked to ultraprocessed food, study finds (Open access)

 

Medscape article – More Evidence Ultraprocessed Foods Detrimental for the Brain (Open access)

 

See more from MedicalBrief archives:

 

Processed meat may be associated with increased dementia risk — UK analysis

 

Biggest dietary problem is nutritious food ignored, not junk food consumed

 

Heavily processed foods linked to earlier death risk

 

Fat or thin, everyone fibs, eats three extra cheeseburgers daily – UK study

 

‘You can't outrun a bad diet’ – BMJ experts

 

 

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