Is eating fast food, cookies, and chips unhealthy for your brain? Sara N. Burke, a neurobiologist at the University of Florida, talks about the studies linking highly processed meals to cognitive decline.

Since many years ago, scientists have been aware that poor diets, especially those high in fat and sugar, can harm the brain and impair cognitive function. A person has little control over many factors that affect cognitive decline, such as genetics and socioeconomic factors. However, more and more evidence is pointing to a poor diet as a risk factor for memory loss as people age normally and as a contributor to the development of Alzheimer’s disease.

However, until recently, there hasn’t been much research comparing the impacts of eating minimally processed versus highly processed meals when assessing how some diets may deteriorate brain function as we age.

Ultra-processed food consumption may aggravate age-related cognitive decline and raise the risk of dementia, according to two recent large-scale studies. Another recent study, however, found no link between eating foods that have undergone extreme processing and cognitive decline in adults over the age of 60.

Compared to unprocessed or minimally processed foods, ultra-processed foods typically have lower nutritional and fiber contents and greater levels of sugar, fat, and salt. Soda, packaged cookies, chips, frozen dinners, flavored almonds, flavored yogurt, distilled alcoholic beverages, and fast food are a few examples of ultra-processed foods.

Because of the additives and preservatives they include, even packaged breads, particularly those rich in nutritive whole grains, qualify as ultra-processed in many situations.

The components that go into most of these delicacies are probably not in your own kitchen.

Contrast ultra-processed foods with processed foods, which have undergone some type of processing but still maintain the majority of their natural qualities, such as canned vegetables, dried pasta, or frozen fruit.

Researchers assessed the incidence of cognitive impairment over a period of eight years across groups of persons who consumed various amounts of ultra-processed foods in a study published in December 2022.

More than 10,000 Brazilian participants who were living at the time of the study provided information on their eating routines over the previous 12 months. The subjects’ cognitive abilities were then assessed over the next years using common memory and executive function tests.

At the beginning of the trial, those who consumed more ultra-processed meals had a modest increase in cognitive deterioration compared to those who consumed little to no ultra-processed foods.

The difference in the rate of cognitive deterioration between the experimental groups was rather small. It is yet unclear whether the slight difference in cognitive deterioration linked to increased consumption of ultra-processed meals would have an important impact on a particular person.

The second study examined the relationship between eating highly processed foods and dementia and included roughly 72,000 participants in the United Kingdom. Over a ten-year period, 1 in 120 members of the group that consumed the most ultra-processed meals had dementia diagnoses. This number was 1 out of 170 for the group that ate little to no ultra-processed foods.

The NOVA classification, a system of categorizing based on the type and intensity of industrial food processing, is used in research to examine the association between health and ultra-processed foods. The NOVA classification has drawn criticism from several nutritionists for its unclear definitions of food processing, which could result in categorization errors. Additionally, they contend that rather than the degree of processing, the possible health concerns associated with consuming ultra-processed foods may be explained by the diet’s high quantities of fat, sugar, and salt and low levels of fiber and minerals.

In addition to having a lot of chemicals, preservatives, or coloring agents, ultra-processed foods frequently lack fiber and other essential nutrients, sharing other characteristics of an unhealthy diet. It is uncertain if consuming food that has undergone greater processing has an adverse effect on health beyond a poor quality diet.

The aging brain goes through biochemical and structural changes that are linked to worsening cognition even when the factors that cause dementia are not present. However, a healthier diet may boost the likelihood of preserving superior brain function in people over the age of 55. The Mediterranean diet and the ketogenic diet, in particular, are linked to greater cognition in old age.

The gut-brain axis, which is the community of bacteria that dwell in the digestive tract, is another way that diet and ultra-processed foods may affect brain health. The gut microbiome helps digestion, has an impact on the immune system and generates neurotransmitters and hormones essential for brain health.

According to studies, the ketogenic and Mediterranean diets alter the gut’s microbial population in ways that are advantageous to the individual. Ultra-processed foods are also linked to changes in the variety and number of gut microbes that have more detrimental consequences.