Reducing salt intake to the level currently recommended for the general population would prevent tens of thousands of heart attacks and strokes annually, Gunn said.
What is too much salt or too little is a matter of debate, said Samantha Heller, a senior clinical nutritionist at NYU Langone Medical Center in New York City.
"However, the salt argument is really all about balance. The reality is few people have any idea how much salt they consume in a day," Heller said.
"This study highlights the fact that too much or too little salt can affect the physiological functions of the body and increase the risk of death," she added.
About 80 percent of Americans' dietary salt comes from processed foods, including bread, cold cuts and pizza as well as restaurant foods and prepared frozen foods, Heller said.
"I like the idea of taking control of how much salt is in the foods we eat by preparing most of our food at home, rather than leaving the salt content up to food companies or restaurants," Heller said.
The studies Graudal and colleagues reviewed included nearly 275,000 people.
They found a correlation between salt intake and health outcomes. Deaths increased when daily consumption was less than 2,645 mg or above 4,945 mg. So both excessively high and low consumption of salt were associated with reduced survival.
But the researchers found little or no variation in death when people kept their salt intake within that daily range.
The study authors said their findings provide a response to a U.S. Institute of Medicine report issued in 2013 that concluded there is scant evidence on what is too much or too little salt.