Study finds high-salt diet deters blood flow

A high-salt diet may spell trouble for the brain — and for mental performance — even if it doesn’t push blood pressure into dangerous territory, new research has found.

A new study has shown that in mice fed a very high-salt diet, blood flow to the brain declined, the integrity of blood vessels in the brain suffered, and performance on tests of cognitive function plummeted.

But researchers found that those effects were not, as has long been widely believed, a natural consequence of high blood pressure. Instead, they appeared to be the result of signals sent from the gut to the brain by the immune system.

The study, conducted by researchers at Weill Cornell Medicine in New York, was published yesterday in the journal Nature Neuroscience.

The research sheds light on a subject of keen interest to scientists exploring the links between what we eat and how well we think, and the mediating role that the immune system plays in that communication. It suggests that even before a chronic high-salt diet nudges blood pressure up and compromises the health of tiny blood vessels in the brain, the oversalted gut is independently sending messages that lay the groundwork for corrosion throughout that vital network.

In the small intestines of mice, the authors of the new research found that a very high-salt diet prompted an immune response that boosted circulating levels of an inflammatory substance called interleukin-17. These high levels of IL-17 set off a cascade of chemical responses inside the delicate inner linings of the brain’s blood vessels.