Nutritionists and doctors have long told us that too much salt is bad for us. It causes the body to retain excess fluid, raising blood pressure and increasing our risk of stroke, heart failure, stomach cancer, and other ailments.

According to a study from New York’s Weill Cornell Medicine, published Wednesday in the journal Nature, high salt consumption may have another toxic effect on us: causing changes in the brain that contribute to dementia. (You may be surprised to learn how many people die from dementia in every state.)

The study’s lead author, Dr. Giuseppe Faraco of Weill Cornell’s Feil Family Brain and Mind Research Institute, said that the new research “provides further evidence of a link between dietary habits and cognitive function.”

Last year, Dr. Faraco and his colleagues found that a molecule called interleukin-17 (IL-17) was released in the small intestine in response to an overdose of sodium. IL-17 enters the bloodstream where it narrows the blood vessels, restricting blood flow and starving the brain of nitric oxide — vital to brain health.

The restricted blood flow, however, wasn’t enough to affect brain function in a major way, so the team continued its research. This year, they discovered that decreased access to nitric oxide also affects the stability of tau proteins, part of the “scaffolding,” or cytoskeleton, that helps distribute nutrients across neurons to keep them functioning healthily. 

A high-salt diet, the study revealed, causes the tau proteins to detach from the cytoskeleton and accumulate in the brain, causing cognitive problems.

The study demonstrates that there is more than one way to keep the brain healthy, according to the Feil Family Institute’s director, Dr. Costantino Iadecola, a professor of neurology at Weill Cornell Medicine. “We’ve got to keep salt in check,” he said. “It can alter the blood vessels of the brain and do so in a vicious way.”

He stresses that the salt that’s really bad for us isn’t what we add at the table — it’s what’s hidden in processed foods and restaurant dishes. Consider these healthy eating habits that will change your life.

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