It may predispose us not only to obesity and diabetes, but also to cognitive decline and neurodegeneration.
The risk of Alzheimer it appears to be increased by various health conditions, genetic factors, and lifestyle and environmental factors that impact the brain over time. But also from one mechanism in particular, related to fructosea type of sugar particularly important in human nutrition and for many animals, the excess of which however seems to predispose us to the development not only of obesity and diabetes, but also of this form of dementia. That’s because fructose is responsible for a cellular mechanism that researchers call “survival response”, a sort of switch that stimulates the search for food and which in the past helped our ancestors to overcome periods of scarcity.
However, in a time of relative abundance of food, scholars suspect this switch is always on, leading us to consume more foods high in fat, sugar and salt, the intake of which causes excessive production of fructose in the brain. “Fructose produced in the brain it can lead to inflammation and, eventually, Alzheimer’s diseasesays the research team who discovered how the entire food response is set in motion by fructose, either consumed or produced by the body.
In other words, when threatened with starvation, early humans developed a survival response that prompted them to forage for food, optimized in various parts of the brain to block out everything in the way, such as recent memories and attention to time. , in order to favor dynamics of attention, rapid evaluation, impulsivity, exploratory behavior and risk-taking. The metabolism of fructose, and its byproduct, intracellular uric acid, helps dampen these nerve centers, allowing increased focus on food gathering.
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The effects of fructose on the brain
The study of this metabolism, detailed in an article onAmerican Journal of Clinical Nutrition, indicated that fructose reduces blood flow to the brain’s cerebral cortex involved in self-monitoring, as well as in the hippocampus and thalamus, meanwhile increasing blood flow around the visual cortex associated with food reward. All of this stimulates the foraging response.
“We believe that, initially, the fructose-dependent reduction in brain metabolism in these regions was reversible and thought to be beneficial – explained the lead author of the study, Professor Richard Johnson of the School of Medicine of the University of Colorado, in the United States – . Despite this, the chronic and persistent reduction in brain metabolism driven by recurrent fructose metabolism leads to progressive brain atrophy and loss of neurons with all the characteristics to Alzheimer’s disease”.
Johnson and his team therefore suggest that Alzheimer’s is “a harmful adaptation” of an evolutionary path of survival, which implies that what in the past served to guarantee food, water and oxygen essential for life can turn into something profoundly negative if applied for long periods. “A study has found that if you keep lab rats on fructose long enough, they build up tau and beta-amyloid proteins in their brains, which are the same proteins seen in Alzheimer’s disease. Johnson added. High levels of fructose they can also be found in the brains of Alzheimer’s patients”.
While more research into the role of fructose and uric acid metabolism in Alzheimer’s is needed, Johnson also suspects that the tendency of some patients to walk away may be a trace of the ancient response to the search for food. “The available data support our hypotheses, but dietary and pharmacological studies, with particular attention to subjects at risk and those with early Alzheimer’s disease, represent an important opportunity to determine whether the inhibition of fructose metabolism may provide benefits in the prevention, management or treatment of this disease”.