All your nerves work by using sodium. Nerves pass an electrical current through your body (as I'm sure you know) - they do this by sodium channels. Sodium moving in and out of the nerve cells is what causes the electrical current to move down the nerves. Without sodium in your diet, your nerves would not work - hence some of the stories above.

But you don't need loads of it and a lot of food has sodium in anyway. I only ever put it on chips... but I'm not the most nerve-healthy person in the world so might not be best to comment on that!