Eating ultra-processed foods increases risk of cognitive decline

By Benedette Cuffari, M.Sc.Dec 5 2022Reviewed by Aimee Molineux

In a recent JAMA Neurology study, researchers report that consuming ultra-processed foods (UPFs) increases the risk of cognitive decline, particularly among middle-aged adults.

Study: Association Between Consumption of Ultra-processed Foods and Cognitive Decline. Image Credit: Ekaterina Markelova / Shutterstock.com

What factors contribute to dementia?

In 2019, dementia was estimated to affect about 57 million worldwide, with 153 million cases expected by 2050 due to the global rise in life expectancy. Despite being one of the most significant causes of disability in high-income countries, there remains a lack of effective treatments for preventing or delaying the development of dementia symptoms.

Nevertheless, lifestyle habits such as regular physical activity, a healthy diet, and not smoking appear to reduce the likelihood of developing dementia. In particular, the daily consumption of whole grains, vegetables, fruits, nuts, and fish has been linked to increased brain volume and the retention of cognitive function over time.

The health impacts of UPFs

UPFs, which are food products that consist of highly processed food components such as oils, fats, sugars, starch, and protein isolates, offer little to no health benefit for the consumer. In addition to these ingredients, UPFs also often consist of artificial flavorings, colorings, emulsifiers, and other cosmetic additives. Some examples of common UPFs include breakfast cereals, sweet and savory snacks, ice cream, ready-to-eat frozen meals, processed meats, and sugar-sweetened beverages.

Over the past 40 years, the production of UPFs by the global food industry has increased substantially. In fact, recent estimates indicate that UPFs comprise 58% of the calories consumed by U.S. citizens, 57% of those consumed by British citizens, 48% of those consumed by Canadian citizens, and 30% of calories consumed by Brazilian citizens.

Previous studies indicate widespread consumption of UPFs is directly related to an increased risk of cardiovascular diseases, metabolic syndrome, and obesity. However, due to the lack of data correlating the risk of UPF consumption and dementia, the current study aimed to better understand this potential association.

About the study

In the current multicenter, prospective cohort study, individuals between the ages of 35 and 74 were recruited from six different cities throughout Brazil, including Belo Horizonte, Porto Alegre, Rio de Janeiro, Salvador, São Paolo, and Vitoria. Data from the study participants were collected in three waves approximately four years apart, beginning in 2008 and ending in 2019.

At baseline, the study participants provided information on the frequency to which they consumed different food and drink products daily. These food products were classified according to the extent of their industrial processing.

Group 1 food products, for example, included unprocessed or minimally processed foods such as fresh, dry, or frozen fruits and vegetables, grains, meat, and milk. Group 2 food products included processed cooking ingredients such as salt, sugar, and oils.

Group 3 consisted of processed foods such as canned fruits, salted, smoked, or cured meat or fish, as well as certain bread and cheese products. Group 4 consisted of UPFs such as flavors, sweeteners, and emulsifiers.

The study participants also underwent cognitive assessments up to three times every four years. These assessments included memory tests such as immediate and late recall, as well as recognition word list tests. Semantic and phonemic verbal fluency tests were also included to assess the participants’ executive function abilities.

High UPF consumption associated with cognitive decline

A total of 10,775 participants were included in the study, with a mean follow-up period of eight years. At baseline, the mean age of the study participants was about 52 years old, almost 55% of whom were female, 53% were White, and 57% had a college degree. Furthermore, the mean body mass index (BMI) of the study participants at baseline was about 27, with a mean total daily calorie intake of 2,856 kcal.

The daily diet of participants that comprised more than 19.9% UPFs experienced a 28% faster rate of global cognitive decline. More specifically, these individuals experienced a 25% faster rate of executive function decline, with no significant change observed in regard to their memory function.

Notably, study participants who were younger than 60 years were more likely to experience global cognitive decline as compared to those aged 60 years or older who consumed similarly high levels of UPFs in their daily diet.

The researchers hypothesize that this decline in executive function could be due to cerebrovascular lesions caused by the chronic consumption of UPFs. UPF consumption may also increase the circulation of proinflammatory factors that subsequently lead to systemic inflammation that affects the brain.

Taken together, the study findings obtained from a large population cohort emphasize the importance of limiting UPF consumption, particularly in middle-aged adults, to preserve cognitive integrity.