Scientists have known for years that unhealthy diets — especially those high in fat and sugar — can lead to it harmful changes in the brain and lead to cognitive impairment.
Many factors that contribute to cognitive decline are beyond a person’s control, such as: genetics and socioeconomic factors. But ongoing research increasingly suggests that a poor diet is a risk factor for memory impairment during normal aging and increases the risk of develop Alzheimer’s disease.
But assessing how some diets can erode brain health as we age, research on the effects of eating minimally processed versus ultra-processed foods has been sparse — that is, until now.
Two recent large-scale studies suggest that eating ultra-processed foods may exacerbate age-related cognitive decline and increase the risk of developing dementia. In contrast, another recent study reported that eating ultra-processed foods was not associated with poorer cognition in people over 60.
Although more research is needed since a neuroscientist who researches how Diet can affect perception Later in life, I find that these early studies add a new level of consideration to how fundamental diet is to brain health.
Lots of ingredients, minimal nutrition
Ultra-processed foods tend to be lower in nutrients and fiber and higher in sugar, fat, and salt than unprocessed or minimally processed foods.
Some Examples of ultra-processed foods These include soda, packaged cookies, chips, frozen foods, flavored nuts, flavored yogurt, distilled alcoholic beverages, and fast foods. Even packaged breads, including those high in nutritious whole grains, are in many cases considered highly processed because of the additives and preservatives they contain.
In other words, the ingredients that make up most of these foods are unlikely to be found in your home kitchen.
But don’t confuse ultra-processed foods with processed foods, which still retain most of their natural properties despite undergoing some form of processing — like canned vegetables, dried pasta, or frozen fruit.
Analyzing Research
In a December 2022 study, researchers compared rates of cognitive decline over about eight years between groups of people who consumed varying amounts of ultra-processed foods.
At the start of the study, over 10,000 participants living in Brazil reported on their dietary habits over the past 12 months. Then, over the following years, the researchers assessed the participants’ cognitive performance using standard tests of memory and executive functioning.
Those who ate a diet higher in ultra-processed foods at the start of the study showed slightly greater cognitive decline compared to those who ate little to no ultra-processed foods. This was a relatively modest difference in the rate of cognitive decline between the experimental groups.
It’s not yet clear if the small difference in cognitive decline associated with higher consumption of ultra-processed foods will have a meaningful effect at the individual level.
The second study, with around 72,000 participants in the UK, measured the link between Consumption of ultra-processed foods and dementia. In the group that ate the highest amounts of ultra-processed foods, about 1 in 120 people were diagnosed with dementia over a 10-year period. For the group that consumed little to no ultra-processed foods, that number was 1 in 170.
Research examining the relationship between health and ultra-processed foods uses the NOVA classificationa categorization system according to the type and extent of industrial food processing.
Some nutritionists have criticized the NOVA classification for there are no clear definitions of food processing what could lead to misclassifications. They also argue that the potential health risks from eating ultra-processed foods could be explained by low levels of fiber and nutrients and high levels of fat, sugar and salt in the diet, rather than the level of processing.
Many ultra-processed foods are high in additives, preservatives, or colorings, while also exhibiting other hallmarks of an unhealthy diet, such as: B. a low fiber and nutrient content. It is therefore unclear whether eating foods that have undergone more processing has an additional negative impact on Health beyond low nutritional quality.
For example, you might eat a fast-food chain burger and fries that are high in fat, sugar, and salt, and ultra-processed. You could make the same meal at home, which could also be high in fat, sugar and salt, but not ultra-processed. More research is needed to determine if one is worse than the other.
Brain Healthy Diet
Even when the processes that lead to dementia are not taking place, the aging brain undergoes biochemical and structural changes associated with deterioration in cognition.
But for adults over 55, a healthier diet could increase the likelihood of maintaining better brain function. In particular, the Mediterranean diet and ketogenic diet are associated with better cognition in older age.
The Mediterranean diet emphasizes the consumption of plant-based foods and healthy fats like olive oil, seeds, and nuts. The ketogenic diet is high in fat and low in carbohydrates, with the primary source of fiber coming from vegetables. Both diets minimize or eliminate the consumption of sugar.
Our research and the work of others show that both diets can undo some of these changes and Improvement in cognitive function – possibly through Reduction of harmful inflammation.
Although inflammation is a normal immune response to injury or infection, chronic inflammation can damage the brain. Studies have shown that excess sugar and fat can contribute to chronic inflammation, and ultra-processed foods might also worsen harmful inflammation.
Another way diet and ultra-processed foods can affect brain health is through the gut-brain axisthis is the communication that takes place between the brain and the gut microbiomeor the community of microorganisms that live in the digestive tract.
The gut microbiome not only aids in digestion, but also influences the immune system by producing hormones and Neurotransmitters critical to brain function.
Studies have shown that the ketogenic and Mediterranean diets change the composition of the microorganisms in the gut in a way that benefits the person. Eating ultra-processed foods has also been linked Changes in type and frequency of gut microorganisms that have more harmful effects.
The insecurities
Deciphering the specific effects of individual foods on the human body is difficult, partly because it is difficult to tightly control people’s diets to study them over long periods of time. Furthermore, randomized controlled trialsthe most reliable type of study for determining causality, are expensive Carry out.
So far, most nutritional studies, including these two, have only shown correlations between eating ultra-processed foods and health. But they can’t rule it out other lifestyle factors such as exercise, education, socioeconomic status, social connections, stress, and many more variables that can affect cognitive function.
This is where laboratory studies with animals are incredibly useful. show rats cognitive decline in old age consistent with humans. It is easy to control rodent diet and activity levels in a laboratory. And rats reach middle to old age within months, shortening study times.
Laboratory-based studies in animals will allow determining whether ultra-processed foods play a key role in the development of cognitive impairment and dementia in humans. As the world population ages and the number of older adults with dementia are increasingthis knowledge cannot come soon enough.
Sara N BurkeAssociate Professor of Neurobiology and Cognitive Aging, University of Florida
This article is republished by The conversation under a Creative Commons license. read this original article.
