The advice to cut salt should be taken seriously by people who are "salt-sensitive" – those whose bodies hang on to the salt they consume, which drives up their blood pressure and creates chronic problems. About 20 percent of the population is salt-sensitive, particularly people who are overweight, African-American, or who have high blood pressure. The CDC recommends that these groups keep their daily salt consumption under 1,500 milligrams.
But for the rest of the population, some scientists say the harmful effects of salt are overblown.
"Salt intake is most dangerous for the person with left ventricular weakening, or congestive heart failure, who really need to be on a low sodium diet," said Dr. Chip Lavie, medical director of cardiac prevention at the Ochsner Clinic Foundation and Hospital in New Orleans. "However, for thin people with good heart function who have low levels of blood pressure, it probably is not so important to keep salt low."
For those groups at special risk or for others who simply want to keep their salt low, Dr. Clyde Yancy, chief of cardiology at Northwestern Memorial Hospital in Chicago, said it's exceedingly difficult, given the amount of salt that lurks in unlikely foods like bread, cookies, and ketchup.
"Nearly 60 percent of our sodium consumption is embedded in our foodstuff and is consumed passively," Yancy said. "Ideally, we would consistently have lower sodium options for most if not all food items with clear labeling. How can a message of the provision of choice in a free market society not be palatable?"
Certain food companies have proved willing to compromise on the salt content of their foods, balancing consumer demand for taste with medical and federal concerns about salt. McDonald's, Kraft, and Campbell's are among the companies that have instituted voluntary sodium reductions in some of their products.
Dr. Jay Cohn, director of the Rasmussen Center for Cardiovascular Disease Prevention at the University of Minnesota, said even eliminating the very high salt content of certain foods like soups or tomato juice would make a difference.
"Modest restriction will not harm anyone and probably will have some small benefit on the whole population," Cohn said. "It is nothing like smoking, which helps nobody and has a profound adverse effect on individuals and on the population." Until the great salt debate shakes out, experts say consumers should focus on other ways to reduce blood pressure and improve their heart health: getting regular exercise and eating a diet full of fruits and vegetables.