Excess Salt Harms the Brain


BY STEVE BORN

The research was published nearly a year ago, but its message remains unchanged and vitally important to know: High salt diets can have seriously negative effects on a number of areas of brain function, leading to an increased risk of cerebrovascular diseases and dementia.

This particular study was conducted by researchers from Weill Cornell Medicine in New York, who used two groups of mice for this study. One group had a diet that was comprised of 4% salt, and the other group’s food content consisted of 8% salt (comparable to a high-salt diet for humans.)

After an 8-week period, the researchers used MRI imaging to photograph and analyze the anatomy and physiology of the mice’s brains. The negative results they found were astounding:

  • A 28% decrease drop in blood flow in the cortex, the part of the brain associated with thinking and processing information from the five senses
  • A 25% blood flow drop in the hippocampus, the area of the brain responsible for processing emotional responses and long term memory

The mice on the higher-salt diet were shown to have a dramatic decrease in the production of nitric oxide, resulting in impaired blood flow in the brain. This translated to the mice developing dementia, as they performed poorer than the other mice on tests such as object recognition and navigating through a maze.

Interestingly, this decline occurred in the high-salt diet mice regardless of blood pressure. Lead researcher, Dr. Costantino Iadecola, states: “We discovered that mice fed a high-salt diet developed dementia even when blood pressure did not rise. This was surprising since, in humans, the deleterious effects of salt on cognition were attributed to hypertension.”

What Dr. Iadecola and colleagues discovered was the high-salt diet increased levels of a protein known as interleukin 17 (IL-17), whose job is to regulate immune and inflammatory responses. However, when levels of IL-17 are too high, that can decrease the production of nitric oxide, which affects brain functions. It should be noted that by discontinuing the high-salt diets and administering IL-17-lowering drugs, Dr. Iadecola was able to reverse this negative process in the mice.

Based on this study, it’s clear that excess salt leads to levels of IL-17 that are too high, which can disrupt and even destroy many functions of the brain. Just as alarmingly, if not more so, elevated IL-17 levels are also associated with many other inflammatory diseases such as asthma, Crohn’s disease, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and more.

According to the Centers for Disease Control and Prevention (CDC), 90% of children and 89% of adults in the US—irrespective of age, race, gender or having high blood pressure—consume more than the recommended limit of 2,300 mg a day for sodium.

A massive amount of research shows that excess sodium (salt) is not beneficial for exercise performance and, even more importantly, is harmful for health. To perform at your best athletically, and to help stave off the detrimental health effects of too much sodium, the answer is abundantly clear: Cut back on your salt intake!