People with half-way decent kidneys can benefit from all electrolytes, which includes salt and potassium.
The amount needed of sodium to reduce death rates is 3,000 - 7,000 mg/day. Above and below, the rate of death increases.
However, you need plenty of potassium, too. Your kidneys determine how much of each your body needs and excretes the rest of both.
Note: Anyone on blood pressure medicines or special diets needs to watch any large changes to potassium or sodium. The drugs can prevent removal of potassium, for instance, leading to a bad situation.
That was the problem for my Mom. Her doc wanted her @ 1500 mg of sodium / day (really hard to do!) We made changes gradually and backed off when her potassium levels started getting a bit high.