Low-Salt Diets May Harm Heart, Study Says

Research appears to reverse long-standing guidelines

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By
HealthDay Reporter

SATURDAY, April 30, 2005 (HealthDayNews) -- New research would appear to upend long-standing advice to limit daily salt intake if you want to protect your heart.

In fact, the new study suggests, the less salt you eat, the greater your risk of dying from heart disease.

The controversial findings, to be presented Saturday afternoon at an American Heart Association meeting in Washington, D.C., challenge U.S. Food and Drug Administration and American Heart Association recommendations that people consume no more than 2,400 milligrams of sodium (about 1 teaspoon of table salt) a day.

"We believe these data do not support" the current guidelines, said lead researcher Hillel W. Cohen, an assistant professor of epidemiology and population health at Albert Einstein College of Medicine in New York City. "We are urging those who make these guidelines to go back to their data and look at additional data prior to making universal recommendations."

In their study, Cohen's team collected data on 7,278 men and women who participated in the Second National Health and Nutrition Examination Survey. During a follow-up of more than 13 years, the researchers looked for the number of deaths from heart disease and the number of deaths from any other cause.

According to Cohen, they found that the intake of less than 2,400 mg of salt a day was associated with a 50 percent higher risk of heart disease.

And they found that as the intake of salt went down, mortality went up: For each 1,000-mg reduction in salt intake, the risk for cardiovascular mortality rose by 1 percent.

"We found that those who had an intake of salt that was less than the 2,400-mg recommendation had higher mortality," Cohen said. "That was true for all-cause mortality and cardiovascular disease mortality."

Cohen believes that the amount of salt that's right for one person may not be right for another. "It is likely that there are differences between individuals with regard to sodium intake," he said. "And it's clear that the data do not support the current recommendations."

According to Cohen, some people cannot tolerate high levels of salt, while others can. "From a biological standpoint, if one's kidneys are working reasonably well, sodium within the usual range of intakes shouldn't be a problem," he said.

Not surprisingly, the findings were challenged by at least one expert, who called them unreliable.

The study results probably reflect effective use of drugs to compensate for the harms of high salt intake, said Dr. David L. Katz, an associate clinical professor of public health and director of the Prevention Research Center at Yale University School of Medicine.

"We have more and stronger antihypertensive medications than ever before," Katz said. "So yes, you can have your salt and normal blood pressure, too -- if you don't mind better living through pharmacotherapy."

As for the link between higher health risks and lower salt intake, Katz said he believed the real connection is the other way around. "Reducing salt intake is tough to do in a country where even breakfast cereal is salt laden," he said. "So I suspect the sickest people are those that work hardest to cut their salt intake."

"It should come as no surprise to learn that the sickest people have the highest mortality rate," he said.

Conventional wisdom is not about jumping to conclusions but is based on the slow accumulation of information over time, Katz said.

"It should not change every time a new research finding gets reported," he added. "The pursuit of scientific truth is not a straight line; there are many missteps, detours and dead ends along the way. But when first reported, it's the papers that ultimately prove to be wrong that sound most exciting."

And his personal advice? "I'm still watching my salt intake," he said, "and recommend you do the same."

More information

The American Heart Association can tell you more about salt in your diet.

SOURCES: Hillel W. Cohen, assistant professor, epidemiology and population health, Albert Einstein College of Medicine, New York City; David L. Katz, M.D., M.P.H., associate clinical professor, public health, and director, Prevention Research Center, Yale University School of Medicine, New Haven, Conn.; April 30, 2005, presentation, American Heart Association, annual conference on cardiovascular disease, epidemiology and prevention, Washington, D.C.

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