The consumption of ultra-processed foods has long been associated with metabolic diseases such as obesity, metabolic syndrome, and type II diabetes. More recent studies have shed light on the connection between ultra-processed foods and cognitive decline, providing an enhanced understanding of the effects that highly processed foods have on overall health and longevity, both in a physical and psychological manner. The proposed mechanism of action for this correlation involves the brain gut microbiome system, in which complex communication pathways among gut bacteria, the gut lining, the vagus nerve, the brain, and systemic circulation affect neuroinflammation and neurodegeneration both of which are highly associated with cognitive decline.
“Ultra-processed foods differ from minimally or regularly processed foods by the addition of substances such as flavors, colors, sweeteners, and emulsifiers, as well as a large percentage of sugars and fats.”
Ultra processed foods are formulations of mostly artificial and unnatural food substances that have gone through rigorous processing and typically include large percentages of sugars, oils, fats, starch, flavorings, emulsifiers, and other cosmetic additives. Importantly, ultra-processed foods differ from minimally or regularly processed foods by the addition of chemicals such as artificial flavors, colors, sweeteners, and emulsifiers, as well as a large percentage of sugars and fats, which normally wouldn’t be found in home-cooked food. These additives are often used to increase shelf life or enhance texture, consistency, or palatability of the food, yet many of them have been found to have negative effects on overall health. Another one of the dangers of ultra-processed foods is that they often constitute a mixture of sugar, fat, and refined starch that can promote and create food addiction and hence overconsumption. Converging evidence from large-scale studies, has found a direct correlation between the consumption of ultra-processed foods and low-grade systemic inflammation. Other studies found an association with metabolic syndrome, type II diabetes, obesity, as well as brain disorders such as depression and neurodegenerative diseases like Parkinson’s and Alzheimer’s disease.
In fact, the association of low-quality, highly processed diets and neurodegeneration has been a hot topic of recent research, which has suggested a direct link between the two. A very recent study published in the journal JAMA investigated 10,775 individuals over an average span of 8 years and found a direct association between higher consumption of ultra-processed foods and a higher rate of cognitive decline, both regarding global and executive functioning. Another study published last year looked at the association between the consumption of ultra-processed foods and cognitive performance in older adults. The researchers found decreased performance in a cognitive exam testing for language and executive function in individuals with higher ultra-processed food consumption. Another recent study published in the journal Oxford Academic examined the same association of ultra-processed food intake and cognitive decline, this time in older patients with type II diabetes, and found that increased consumption of such a diet was associated with a higher rate of cognitive decline, in both global and executive aspects. All these findings from well-controlled, large-scale studies suggest that a high consumption of ultra-processed foods may create cognitive decline in older age, though large-scale, high-quality studies of causation have yet to be carried out.
Targeting the underlying pathways of these associations between ultra-processed food intake and cognitive decline, several studies have investigated the effects of consumption of highly processed foods on the brain gut microbiome system and found variations in both composition and diversity of important gut microbiota, correlating with increased risk of metabolic and brain disease.
The intake of ultra-processed food is generally associated with a reduced intake of plant derived healthy food components such as fiber, vitamins, polyphenols, and minerals, combined with an increased intake of sugar and saturated fat which have been associated with a reduced diversity of the gut microbiome and a reduced prevalence of short chain fatty acid producing microbial species. Such a systemic dysregulation of the immune system may negatively affect multiple organs and tissues, including adipose tissue, the vascular system, the liver and the brain, the latter being a risk factor for vulnerable individuals to develop early cognitive decline.
On the other hand, a Mediterranean style diet has been associated with gut microbiome changes that suggest decreased risk for cognitive decline. Several studies looked at changes in the gut microbiome as a result of adherence to a Mediterranean-style diet and found increases in the bacteria that are associated with decreases in systemic inflammation, enhanced brain health, and decreased risk for cognitive decline. Looking at nine different cohort studies with a total of 34,168 participants found that the highest Mediterranean diet score, summarized from all studies, had an inverse association with the development of cognitive decline. This, and converging evidence from large-scale studies suggest that high adherence to a Mediterranean-style diet may decrease the risk for conditions of cognitive decline. Given the extensive literature about the relationship of the gut microbiome changes (in particular reduction of butyrate producing species) and their effects on systemic inflammation and brain health, it is likely that the gut microbiome plays an important role in the association of ultra-processed food intake and increased risk for cognitive decline.
“Minimizing one’s consumption of processed foods, and especially ultra-processed foods will be the first step toward improved metabolic health and decreased risk for neurodegeneration.” (This should not be news to anyone...sadly, it is.)
In conclusion, the intake of ultra-processed food is highly associated with greater risk and development of cognitive decline. To decrease the risk for development of dementia and other neurodegenerative conditions, it is hence best to cultivate a healthy gut microbiome by following a largely plant based diet high in fiber, nutrients, vitamins, and polyphenols. Such a diet is constituted by high intake of vegetables, fruit (especially berries), whole grains, extra virgin olive oil, fresh nuts, and other (preferably organic) whole foods. Minimizing one’s consumption of processed foods, and especially ultra-processed foods will be the first step toward improved metabolic health and decreased risk for neurodegeneration.
I must say, aside from the buffet of studies available to support these findings, common sense should weigh in with even the most apathetic of humans. If you can not pronounce it or even more simply, if the ingredient list contains more inputs than the food itself...we might want to question the quality and potential health risks and benefits.
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