Results from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), which included participants aged 35 and older, showed that higher intake of UPFs was significantly associated with a faster rate of decline in both executive and global cognitive function.
“Based on these findings, doctors might counsel patients to prefer cooking at home [and] choosing fresher ingredients instead of buying ready-made meals and snacks,” said coinvestigator Natalia Gonçalves, PhD, University of São Paulo, Brazil.
Presented at the Alzheimer’s Association International Conference, the findings align with those from a recent study in Neurology. That study linked a diet high in UPFs to an increased risk for dementia.
Increasing worldwide consumption
UPFs are highly manipulated, are packed with added ingredients, including sugar, fat, and salt, and are low in protein and fiber. Examples of UPFs include soft drinks, chips, chocolate, candy, ice cream, sweetened breakfast cereals, packaged soups, chicken nuggets, hot dogs, fries, and many more.
Over the past 30 years, there has been a steady increase in consumption of UPFs worldwide. They are thought to induce systemic inflammation and oxidative stress and have been linked to a variety of ailments, such as overweight/obesity, cardiovascular disease, and cancer.
UPFs may also be a risk factor for cognitive decline, although data are scarce as to their effects on the brain.
To investigate, Dr. Gonçalves 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.
Participants were grouped according to UPF consumption quartiles (lowest to highest). Cognitive performance was evaluated by use of a standardized 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 8 years, UPF intake in quartiles 2 to 4 (vs. quartile 1) 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 ultraprocessed 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 ultraprocessed foods,” Dr. Gonçalves reported.
“Considering a person who eats a total of 2,000 kcal per day, 20% of daily calories from ultraprocessed foods are about two 1.5-ounce bars of KitKat, or five slices of bread, or about a third of an 8.5-ounce package of chips,” she explained.
Dr. Gonçalves noted that 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.