If everyone consumed half a teaspoon less salt per day, there would be between 54,000 and 99,000 fewer heart attacks each year and between 44,000 and 92,000 fewer deaths, according to the study, which was conducted by scientists at University of California San Francisco, Stanford University Medical Center and Columbia University Medical Center.
The report comes as health authorities at federal, state and municipal levels are considering policies that would have the effect of pressuring food companies to reduce salt in processed foods, which are considered to be the source of much of the salt Americans eat.
Last week, New York City announced an initiative to urge food manufacturers and restaurant chains to reduce salt in their products nationwide by 25 percent over the next five years. California, according to an author of the study, Kirsten Bibbins-Domingo, an associate professor of medicine and epidemiology at University of California, San Francisco, is considering setting salt limits on food the state purchase for schools, prisons and other public institutions.
A panel appointed by the Institute of Medicine, the widely respected independent research arm of the National Academies of Science, is close to issuing a report that will make recommendations about reducing salt intake, including actions government and manufacturers can take.
Dr. Bibbins-Domingo also said the Food and Drug Administration was considering whether to change the designation of salt from a food additive that is generally considered safe to a category that would require companies to give consumers more information alerting them to high levels of salt in food. An F.D.A. spokesman was unable to say Wednesday whether such discussions were taking place. “We are actively looking at how to improve the nutrition content of the American content,” he said.
“For 40 years in this country we’ve been trying to get individuals to reduce the amount of sodium we consume and it hasn’t worked,” said Cheryl A. M. Anderson, an assistant professor of epidemiology and international health at Johns Hopkins University and a member of the Institute of Medicine panel.
“We need to collectively come together and approach the problem with a combination of efforts, including changing the food supply,” said Dr. Anderson, who also is a co-author of an editorial about the study in The New England Journal of Medicine. “This type of evidence really helps us support that movement toward not just relying on the individual to do something that is really difficult, limit salt.”
The study involved a computerized model that analyzed previous studies to estimate the benefits of salt reduction on lowering blood pressure and the lowered blood pressure’s effect on decreasing heart disease, stroke and heart attacks.
The researchers found that everyone would benefit from less salt, but people at higher risk for heart problems — blacks, people with hypertension and people over 65 — would benefit most.
Not every expert in the field of salt science was persuaded.
Michael Alderman, a professor of medicine and epidemiology at the Albert Einstein College of Medicine, said the research was “based on the assumption that there would be no other effects of reduced sodium, but that’s not so.” He said that salt reduction could lead to insulin resistance and imbalances of hormones in the adrenal and kidney systems, and that clinical trials comparing these effects with the benefits of lowering blood pressure needed to be conducted.
Dr. Norman K. Hollenberg, a professor of medicine at Harvard Medical School, questioned the assertion that the benefit of salt-reduction policies would be as great as antismoking policies.
“If we’re going to change something, smoking would be No. 1,” Dr. Hollenberg said. “Salt intake would come somewhere well below it.”
Dr. Bibbins-Domingo said that for many people the decrease in blood pressure would be modest, which is why, she said, “many physicians have thrown up their hands and said, ‘I’m not going to advise my patients to reduce salt because it’s too hard for patients and the benefits for any individual are small.’
“But small incremental changes in salt, such as lowering salt in tomato sauce or breads and cereals by a small amount, would achieve small changes in blood pressure that would have a measurable effect across the whole population,” she said. “That’s the reason why this intervention works better than just targeting smokers.”