A study carried out by scientists at the Weill Cornell Medicine School in New York City (USA) concludes that too much salt in our diet can cause cognitive deficits. Fortunately, these negative effects can be reversed and the work, published in the journal Nature Neuroscience, shows us how.
The authors suggested that a possible mechanism behind these negative effects involves so-called endothelial cells within brain blood vessels . Endothelial cells are found in blood vessels and are responsible for regulating vascular tone; however, high salt intake has been associated with dysfunction of these cells.
Although it is known that epithelial dysfunction can bring a plethora of chronic diseases, it is not yet clear how salt-induced endothelial dysfunction can affect the brain in the long term. It is not a trivial matter, since the brain depends to a great extent on a stable flow of oxygen to function properly.
Excess salt affects the gut-brain axis
For their experiment, the experts fed a group of mice the equivalent of a high-salt human diet for a period of 12 weeks. After the first few weeks, endothelial dysfunction was observed, as well as a reduction in blood flow to the brain in the mice. Furthermore, behavioral tests revealed cognitive impairment in the rodents. His blood pressure, however, was unchanged.
An important discovery was the increase in the so-called TH17 white blood cells in the intestine. In turn, the high number of TH17 cells led to an increase in the levels of a pro-inflammatory molecule called plasma interleukin-17 (IL-17).
The researchers were also able to identify the molecular pathway through which higher levels of IL-17 in the blood led to negative cognitive and cerebrovascular effects.
Would these effects be replicated in human cells? They treated human endothelial cells with IL-17 and obtained similar results.
“The findings reveal a gut-brain axis whereby diet-related environmental factors lead to an adaptive immune response in the gut, promoting neurovascular dysregulation and cognitive decline, ” the authors explain.
Not everything is lost
The good news is that the negative effects of the high-salt diet appear to be reversible. The mice returned to a normal diet after 12 weeks, and the results were encouraging.
“The deleterious effects of were eliminated by returning the mice to a normal diet, pointing to the reversibility of vascular dysfunction and cognitive decline,” the experts write.
The findings suggest that lifestyle changes, or a new class of drugs, could help offset the negative effects of a high-salt diet.
Reference: Dietary salt promotes neurovascular and cognitive dysfunction through a gut-initiated TH17 response. Nature Neuroscience (2018) DOI: doi: 10.1038 / s41593-017-0059-z
