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Yes, No . . . or Low?

For years we've been told to cut our salt intake to reduce the risk of hypertension and other ailments. And we did. But now, some experts say, many of us don't benefit from and, in fact, can be harmed by a low-sodium diet.

June 22, 1998|THOMAS H. MAUGH II | TIMES MEDICAL WRITER

From the dim beginnings of the human race, people have craved salt.

Early hominids sought out salt licks to satisfy their needs. The first agriculturists put it in their bread. As cities and towns began to develop, men established the first trading routes in order to put salt on their tables.

In some countries, salt was traded ounce for ounce for gold. The Chinese made coins out of salt, and the Romans paid their soldiers a salarium, or payment in salt, that is the precursor of the modern salary.

Today, however, salt is viewed a bit differently--at least by health authorities. Although humans still crave it avidly and food processors use it routinely to enhance flavor, most major medical groups urge us to remove it from our tables and our kitchens.

Salt, they say, is a leading cause of high blood pressure, and this hypertension, in turn, is a major cause of heart attacks, strokes and death. To combat its foul effects, they say, virtually everyone should put the saltcellar down. Bland is beautiful.

But hold on, a vocal minority of researchers insist. While it is clear that salt is linked to hypertension in some individuals, they say, the vast majority of people are either unaffected by it or can control hypertension by simply eating a healthier diet. And in some cases, low salt consumption might even be dangerous.

Asking everyone to cut back on salt to reduce the risk for a few, they argue, is like using a blunderbuss to kill a fly.

"The issue is not blood pressure," says Dr. Michael H. Alderman of the Albert Einstein College of Medicine in New York City, president of the American Society of Hypertension. "The issue is life, heart attacks and strokes. There is no evidence that [lowering salt intake] will extend life or make it better in any way. Absent that evidence, we are not justified in asking 250 million Americans to change their diet."

"For 20 years, we have not told people what they need to hear, which is that the best way to control blood pressure is to control weight, drink alcohol only in moderation and exercise," says Dr. David A. McCarron of Oregon Health Sciences University. "If I had to make a list [of health factors], sodium chloride [reduction] would not make the top 10."

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Others, of course, disagree. "We have the massive accumulation of 50 years of data on the relationship between salt intake and blood pressure, and the havoc that higher average blood pressure wreaks in the United States," says Dr. Jeffrey Cutler of the National Heart, Lung and Blood Institute. "I don't think we can say with a great degree of certainty what the optimally low sodium intake should be, but we can say that the vast majority of people eat far too much salt."

"This is an issue where the scientific community is really, honestly divided," adds Rodman D. Starke, senior vice president for scientific affairs at the American Heart Assn.

High blood pressure in an adult is defined as greater than or equal to 140/90, where 140 millimeters of mercury (mm Hg) is the systolic pressure (when the heart is beating) and 90 mm Hg is the diastolic pressure (the pressure between beats). One in every four adult Americans, about 50 million, has high blood pressure, but an estimated 35% of those don't know it.

According to the heart association, high blood pressure kills about 38,000 Americans each year and contributes to the deaths of more than 180,000. But of all those 50 million with high blood pressure, only 21% receive adequate therapy. Another 27% receive inadequate therapy, while 52% receive no therapy at all.

There is no question that a link exists between salt and hypertension, says Dr. Myron H. Weinberger of the Indiana University School of Medicine. His studies, like those of others, have shown that about 60% of hypertensives are sensitive to salt--that is, their blood pressure rises when they consume more salt and it falls when they consume less. The study showed that 73% of African American hypertensives are salt-sensitive as are about half of white hypertensives.

In the population with normal blood pressure, about 25% are sensitive to salt, and most of those are older than 60. In both of these groups, says Dr. Suzanne Oparil of the University of Alabama at Birmingham School of Medicine, "the problem is we don't know who these people are."

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The average American consumes about 12 grams--about two teaspoons--of salt every day, about twice the amount recommended by such authorities as the National Institutes of Health and the heart association.

Only about a quarter of that 12 grams originates in the salt shaker at home. The rest comes from processed foods--everything from soup to nuts. It is the presence of salt in so much purchased food that makes it difficult to drastically reduce consumption.

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