Many factors that contribute to cognitive decline are beyond a person’s control, such as genetics Y socioeconomic factors. But ongoing research increasingly indicates that a Poor diet is a risk factor. memory problems during normal aging and increases the risk of develop Alzheimer’s disease.
But when evaluating how some diets can erode brain health as we age, research on the effects of consuming minimally processed versus ultra-processed foods has been scant—until now, that is.
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 consumption of ultra-processed foods was not associated with worse cognition in people older than 60 years.
Although more research is needed, as neuroscientist who investigates how Diet can influence cognition. Later in life, I find that these early studies add a new layer to considering how critical nutrition 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 compared to unprocessed or minimally processed foods.
Some examples of ultra-processed foods include soft drinks, prepackaged cookies, chips, frozen meals, flavored nuts, flavored yogurt, distilled spirits, and fast foods. Even packaged breads, including those rich in nutritious whole grains, qualify as ultra-processed in many cases due to the additives and preservatives they contain.
Another way to look at it: You probably won’t find the ingredients that make up most of these foods in your kitchen at home.
But don’t confuse ultra-processed foods with processed foods, which still retain most of their natural characteristics, even though they’ve undergone some form of processing, such as canned vegetables, dried pasta, or frozen fruit.
Analyzing the research
In a December 2022 study, researchers compared the rate of cognitive decline over about eight years between groups of people who ate different amounts of ultra-processed foods.
At the start of the study, more than 10,000 participants living in Brazil reported their eating habits for the previous 12 months. Then, over the next few years, the researchers assessed the participants’ cognitive performance with standard tests of memory and executive function.
Those who ate a diet that contained more ultra-processed foods at the start of the study showed slightly greater cognitive decline compared to those who ate little or no ultra-processed foods. This was a relatively modest difference in the rate of cognitive decline between the experimental groups.
It is not yet clear whether the small difference in cognitive decline associated with higher consumption of ultra-processed foods will have a significant effect at the level of an individual person.
The second study, with nearly 72,000 participants in the UK, measured the association between eating ultra-processed foods and dementia. For 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 ate little or no ultra-processed foods, this number was 1 in 170.
Research examining the relationship between health and ultra-processed foods uses the NOVA classificationwhich is a categorization system based on the type and extent of industrial food processing.
Some nutritionists have criticized the NOVA classification for not having clear definitions of food processing, which could lead to misclassification. They also argue that the potential health risks of consuming ultra-processed foods could be explained by low levels of fiber and nutrients and high levels of dietary fat, sugar and salt rather than the amount of processing.
Many ultra-processed foods are high in additives, preservatives, or coloring, but also have other hallmarks of an unhealthy diet, such as being low in fiber and nutrients. Therefore, it is not clear whether eating foods that have undergone further processing has an additional negative impact on health beyond the poor quality of the diet.
For example, you could eat a hamburger and fries from a fast food chain, which would be high in fat, sugar, and salt, as well as being ultra-processed. You could make that same meal at home, which might also be high in fat, sugar, and salt, but it wouldn’t be ultra-processed. More research is needed to determine if one is worse than the other.
healthy diets for the brain
Even when the processes that lead to dementia do not occur, the aging brain undergoes biochemical and structural changes that are associated with worsening cognition.
But for adults 55 and older, a healthier diet might increase the likelihood of maintaining better brain function. In particular, Mediterranean diet Y ketogenic diet are associated with better cognition in later life.
The Mediterranean diet emphasizes the consumption of plant-based foods and healthy fats, such as olive oil, seeds, and nuts. The ketogenic diet is high in fat and low in carbohydrates, with vegetables being the main source of fiber. Both diets minimize or eliminate sugar intake.
Although inflammation is a normal immune response to injury or infection, chronic inflammation can be detrimental to the brain. Studies have shown that excess sugar and fat may contribute to chronic inflammation, and ultra-processed foods could also exacerbate harmful inflammation.
Another way that diet and ultra-processed foods can influence brain health is through the gut-brain axisWhat is the communication that occurs between the brain and the gut microbiomeor the community of microorganisms that live in the digestive tract.
The gut microbiome not only helps with digestion, but also influences the immune system, while producing hormones and neurotransmitters that are critical for brain function.
Studies have shown that the ketogenic Y mediterranean diets change the composition of microorganisms in the intestine in a way that benefits the person. Consumption of ultra-processed foods is also associated with alterations in the type and abundance of intestinal microorganisms that have more harmful effects.
It’s hard to tease out the specific effects of individual foods on the human body, in part because it’s problematic to keep tight tabs on people’s diets to study them over long periods of time. It’s more, randomized controlled trialsthe most reliable type of study to establish causality, They are expensive to carry out.
So far, most nutritional studies, including these two, have only shown correlations between consumption of ultra-processed foods and health. But they can’t rule out other lifestyle factors such as exercise, education, socioeconomic status, social connections, stress, and many more variables that can influence cognitive function.
This is where laboratory animal studies are incredibly useful. rat show Cognitive decline in old age that parallels that of humans. It is easy to control the diets and activity levels of rodents in a laboratory. And rats go from middle age to old age in a matter of months, shortening study times.
Laboratory studies on animals will make it possible to determine if ultra-processed foods are playing a key role in the development of cognitive decline and dementia in people. As the world population ages and the number of older adults with dementia increasesthis knowledge cannot come soon enough.
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