https://immieats.com/the-sodium-myth-debunked-why-salt-is-not-the-enemy/

just one excerpt 

"Dr. Andrew Huberman is a professor of neurobiology at Stanford University School of Medicine. According to Dr. Huberman, sodium is one of the key elements that promote healthy physical and especially brain function. 

 A healthy concentration of sodium in our body makes our nervous system more efficient and able to fire more rapidly. This gives us an edge in terms of physical activity and sports that need quick reflexes and movements. An interesting study about consumption of natural sea-salt in salt-sensitivity cases found that eating sea salt actually offers some protection against hypertension and kidney damage.

For example, eating less sodium forces the body into a sort of sodium-saving mode. This is when your body doesn’t get enough sodium from the regular diet and so the kidneys start to save as much sodium as they can for regular bodily function. 

This is done by releasing hormones such as renin and aldosterone, both of which cause the body to retain sodium and lose potassium. This, in turn, increases blood pressure. "