I just finished the book "The Salt Fix" by Dr. James DiNicolantonio. It's a fairly technical book, so I don't recommend it for pleasure reading. If you want to hear the author in an interview, here's a link.
Since 1980 the US government has been telling us to limit our intake of sodium. But there is little to no research that shows a correlation between sodium intake and blood pressure, let alone heart disease. In fact, when the body does not get enough salt, the blood volume goes down which puts the body in a stressful dehydration mode. The heart rate goes up, vessels constrict and salt-retaining hormones and insulin are released. In many cases, the blood pressure increases!
The three countries with the lowest rate of death due to coronary heart disease are Japan, France, and South Korea. They all eat a very high salt diet-- think cheese, seaweed and kimchi.
Your body can handle a lot of salt. And usually our built-in "salt-meters" will prevent us from eating salt cubes. It's the sugar ones we need to watch out for.
The current recommendation is 2,300 mg of sodium limitation (less than 1 teaspoon). A better amount is 3,000 to 6,000 mg/ day (about 1-1/3 to 2-2/3 teaspoons). If you sweat a lot, drink coffee or take certain medications that "waste" salt, you'll need to take even more to maintain a good balance of salt in the body.
Here's the best way I've found to increase my salt intake. I sprinkle some grains of salt in my hand, pop them in my mouth and then chase it down with some water. I always feel a little burst of energy afterwards.
Don't fear the salt shaker. Sprinkle away!