In a recent study in JAMA Neurology, researchers report that consumption of ultra-processed foods (UPF) increases the risk of cognitive impairment, especially among middle-aged adults.
Study: Association between the consumption of ultra-processed foods and cognitive decline. Image credit: Ekaterina Markelova / Shutterstock.com
What factors contribute to dementia?
In 2019, dementia is estimated to affect an estimated 57 million worldwide, with 153 million cases expected by 2050 due to global increases in life expectancy. Despite being one of the most important causes of disability in high-income countries, there is still a lack of effective treatments to prevent or delay the development of dementia symptoms.
However, lifestyle habits such as regular physical activity, a healthy diet and not smoking appear to reduce the likelihood of developing dementia. In particular, daily consumption of whole grains, vegetables, fruits, nuts, and fish has been linked to increased brain volume and retention of cognitive function over time.
The health impacts of UPFs
UPFs, which are food products consisting of highly processed food components such as oils, fats, sugars, starches and protein isolates, offer little or no health benefit to the consumer. In addition to these ingredients, UPFs also often consist of artificial flavors, colors, emulsifiers, and other cosmetic additives. Examples of common UPFs include breakfast cereals, sweet and savory snacks, ice cream, frozen ready-to-eat meals, processed meats, and sugary drinks.
Over the past 40 years, the production of UPF by the global food industry has increased substantially. In fact, recent estimates indicate that UPF accounts for 58% of the calories consumed by US citizens, 57% of the calories consumed by British citizens, 48% of the calories consumed by Canadian citizens, and 30% of the calories consumed by by Brazilian citizens.
Previous studies indicate that widespread UPF consumption is directly linked to an increased risk of cardiovascular disease, 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 possible association.
About the study
In the current multicenter prospective cohort study, individuals aged 35–74 years were recruited from six different cities across Brazil, including Belo Horizonte, Porto Alegre, Rio de Janeiro, Salvador, São Paolo, and Vitoria. Data from study participants was collected in three waves roughly four years apart, beginning in 2008 and ending in 2019.
At first, study participants provided information about how often they consumed different foods and beverages on a daily basis. These food products were classified according to the extent of their industrial transformation.
Group 1 food products, for example, included unprocessed or minimally processed foods such as fresh, dried or frozen fruits and vegetables, cereals, 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 fruit, salted, smoked or cured meats or fish, as well as certain bread and cheese products. Group 4 consisted of UPFs such as flavors, sweeteners, and emulsifiers.
Study participants also underwent cognitive assessments up to three times every four years. These assessments included memory tests such as immediate and delayed recall, as well as word recognition word list tests. Semantic and phonemic verbal fluency tests were also included to assess participants’ executive function skills.
High UPF consumption associated with cognitive decline
A total of 10,775 participants were included in the study, with an average follow-up period of eight years. At baseline, the average age of study participants was about 52, nearly 55% of whom were female, 53% were white, and 57% had a college degree. In addition, the average body mass index (BMI) of the study participants at baseline was about 27, with an average total daily calorie intake of 2,856 kcal.
Participants whose daily diet comprised more than 19.9% of UPF experienced 28% faster overall cognitive decline. More specifically, these individuals experienced a 25% faster decline in executive function, with no significant change observed in their memory function.
In particular, study participants who were younger than 60 were more likely to experience global cognitive decline compared to those 60 and older who consumed similarly high levels of UPF in their daily diet.
The researchers hypothesize that this decrease in executive function could be due to cerebrovascular injury caused by chronic UPF consumption. UPF consumption may also increase the circulation of pro-inflammatory factors that subsequently lead to systemic inflammation affecting the brain.
Taken together, the study results obtained from a large population cohort emphasize the importance of limiting UPF consumption, especially in middle-aged adults, to preserve cognitive integrity.
Journal reference:
- Goncalves, NG, Ferreira, NV, Khandpur, N., et al. (2022). Association between the consumption of ultra-processed foods and cognitive decline. JAMA Neurology. doi:10.1001/jamaneurol.2022.4397.