Americans like to eat out.  It's been estimated they go out for a meal or take out food from a restaurant at least five times a week. But there is growing concern about the quality of the food they consume.  One health group is warning that some restaurants put dangerously high amounts of salt in the food they serve.  

Doctors routinely warn patients to put the salt shaker down.  It turns out there is way too much salt already in the food prepared in many restaurants.

Michael Jacobson is with the Center for Science in the Public Interest, a food safety and nutrition organization in Washington, D.C.

"Salt is probably the single deadliest ingredient in our food supply," he said. "Causing tens of thousands of unnecessary deaths a year.  And restaurants are a big part of the problem."

Jacobson says adults with high blood pressure, or who are middle aged or older, should consume no more than 1500 milligrams of sodium [salt] a day.  Children should consume no more than 1200 milligrams a day.  

Jacobson's organization looked at the contents of at least 100 meals from 17 American restaurant chains and found that as much as four days' worth of salt was in some dishes.

"This is the average amount of salt that Americans consume per year (holding up a jar).  It's eight pounds [3.6 kilograms] and the experts say cut it down at least halfway, and ideally almost two thirds of the way down," Jacobson said.

A certain amount of salt in food is okay.  According to the Mayo Clinic, salt maintains the right level of fluids in your body, helps transmit nerve impulses and contract and relax muscles.  

But too much salt leads to fluid retention, higher blood pressure, and cardiovascular and kidney diseases.

Dr. Lawrence Appel of the Johns Hopkins School of Public Health says the elderly
and those sensitive to sodium are vulnerable when the waiter brings the food.

"They consume a massive amount of salt without knowing it," he said. "They end up short of breath and come to the [hospital] emergency room with flagrant heart failure."

Dawn Sweeney represents the National Restaurant Association in the United States. She says her members are cutting back on salt content. "You look across the menu in those restaurants and there are many choices that are low in sodium," she states.

The Center for Science in the Public Interest and the American Medical Association have called for government limits on the amount of salt in commercially prepared food.  

For now, those who make and serve that food are not required to reveal what goes into the recipe.