The salt shakeout.

"I don't worry about how much salt I eat because my blood pressure is low," says 27-year old Karen Brown of Washington, D.C.

What a relief. What a mistake.

Myths about salt are almost as common as salt shakers. That's partly because of the astute public relations professionals at the industry's Salt Institute, and partly because some scientists disagree--so what else is new?--about the dangers of salt.

Yet after exhaustively reviewing all of the evidence, every major health authority, from the U.S. Surgeon General to the National Academy of Sciences, has urged Americans to cut back on salt--or sodium, to be precise.

And it's not just your blood pressure that's at stake.

"Hypertension Research Challenges Role of Salt," declared the headline in The New York Times in December of 1991. Does that mean you don't have to worry about sodium?

Call that Myth Number One.

"The recommendations that today's high salt intake be reduced are based not on any one study," says Jeremiah Stamler, a renowned cardiovascular disease expert at Northwestern University Medical School in Chicago. "They're based on hundreds of studies, over many decades, using every method of medical research." (1)

Fretting over salt needn't raise your blood pressure. Just don't fall for the "I don't have to worry about salt" trap. That--and half a dozen other myths-- could get you into trouble.

Myth: If you don't have high blood pressure, you don't have to worry about salt. Sorry. Fifty million Americans have high blood pressure, which means at least 140 over 90. But just because your pressure isn't high doesn't mean it's optimal-- that is, below 120 over 80.

"The risk of dying of heart disease or stroke doesn't start to rise at 140 over 90, but at a systolic pressure of 120 or a diastolic pressure of 80," says Rose Stamler, a researcher at the Northwestern University Medical School and Jeremiah Stamler's wife. "And sodium has an effect on blood pressure across all levels."

Even though the risk is greater for people with the highest blood pressures, she adds, "so many of us are between 120 and 139 systolic and 80 and 89 diastolic that we contribute more than a third of the preventable deaths caused by above-optimal pressure."

Add those "in-between" people to the 50 million or so with "high" pressure, and we're talking about 80 percent of Americans aged 35 or above with blood pressures that increase their risk of both heart disease and stroke. We're talking about an epidemic.

Myth: If your blood pressure is low, it'll stay low.

Even if your pressure is optimal now, if you live in an industrialized country, it's likely to rise as you get older.

In the INTERSALT study that Rose Stamler helped organize, systolic blood pressure rose an average of 15 points between the ages of 25 and 55.

"That's not small stuff," she says. "If lifetime salt intake were lower by about one teaspoon a day--that's 2,300 mg of sodium-blood pressure would still rise with age, but the increase would be six, not 15 points. That would mean a 16 percent drop in coronary heart disease deaths, and 23 percent fewer stroke deaths at age 55."

And if those numbers don't impress you, consider this: "Cutting back on salt may have a small impact on your blood pressure," says Jeffrey Cutler, a hypertension expert at the National Heart, Lung and Blood Institute in Washington. "But that can have a strong impact on whether you'll cross a threshold and your doctor will treat you with medication."

Myth: Most people's blood pressures aren't sensitive to salt.

That's based largely on widely publicized--thank you, Salt Institute---but flawed studies.

"These are really poor studies," says Rose Stamler. "Most were small---a half dozen or a dozen people. Most were short-term, which has nothing to do with a lifetime of exposure. And most were not repeated in the same people to see how their responses vary from time to time."

That's because most of the studies were designed not to estimate the number of people who are salt-sensitive, but to understand how salt might raise blood pressure, says Cutler. "1 think they've been misused."

"You and I may react differently to the same salt intake," says Rose Stamler, "just as when I eat a lot of fat and cholesterol, my serum cholesterol won't go as high as my husband's.

"As with anything in biology, there's a variation in response. But most of us are sensitive to one degree or another."

Myth: High blood pressure is the only danger posed by salt.

You can add these to the list:

* Osteoporosis. It causes 1.5 million fractures a year and affects 20 million Americans, mostly older women. And most people don't know that much of their bone mass has vanished until what's left of a hip or leg breaks.

"Spinal crush fractures and [hip] fractures are already a major scourge of the elderly and an important cause of discomfort, deformity, loss of independence, and mortality," explains osteoporosis expert Ailsa Goulding of the University of Otago Medical School in Dunedin, New Zealand, in the New Zealand Medical Journal.(2) As the population ages, she adds, the ranks of the bone-poor will swell.

Most people rightly think of too little calcium as a cause of osteoporosis, but too much sodium is another culprit. The reason is simple: The more sodium you excrete, the more calcium you lose. No one knows if the sodium pulls calcium out of your bones or compels your kidneys to excrete it.(3)

"On average, urinary calcium increases by about [23 mg] for every teaspoon of salt consumed," explains Goulding. "An uncompensated calcium loss of 23 mg per day is large enough to dissolve one percent of the skeleton annually--that is, ten percent in a decade!"

That's okay if you consume enough calcium to compensate for the loss, but most people don't. Reducing sodium intakes to about 1,600 mg a day would lower the calcium we excrete by about a third, notes Goulding. Excess sodium is as important a calcium-waster as excess protein.

And it's not just older folks who should be concerned. The best strategy for avoiding osteoporosis is to build up your bone mass before the age of 35. Says Goulding: "If you wish to grow a strong skeleton when you are young and conserve bone mass as you get older, it is sensible to spare the salt."

Stomach cancer. Worldwide, it's still one of the most common malignancies. But in the U.S., death rates from stomach cancer have plunged by more than 75 percent since the 1930s.

The risk is still excessive among African-Americans, Latino-Americans, Native-Americans, and immigrants from high-risk areas like Asia. Yet no one can afford to ignore stomach cancer, because when it strikes, it's a killer.

Of the 25,000 Americans who are diagnosed each year, only 13 percent survive another five years. This is one cancer you want to avoid... and avoiding excess salt may help.

Not that it's the only cause. "In the case of stomach cancer, three factors appear to be dominant: infection [with a bacterium called Helicobacter pylori], excessive salt intake, and a diet low in fresh fruits and vegetables," explains Pelayo Correa in The New England Journal of Medicine.(4) Correa is a stomach cancer expert at the Louisiana State University Medical Center in New Orleans.

Excess salt irritates the stomach lining, causing cells to reproduce more often. That alone could increase the risk of cancer. And in animal experiments, salt also makes cancer-causing chemicals more potent. That would explain why researchers have found a greater salt intake among Japanese, Chinese, Italians, and Americans who have stomach cancer.(5)

I might also help explain why U.S. rates have fallen so swiftly since the 1930s. Before then, we used salt instead of refrigerators to preserve many foods (though we also ate fewer fresh fruits and vegetables).

But we're still not home free. In a recent study in Buffalo, New York, stomach cancer patients were more likely to have consumed roughly 3,000 mg or more of sodium a day.(6) That's what the average American woman eats. The average man eats 4,000 mg.

The easiest way to cut the salt is to throw out your shaker.

That helps. But only 15 percent of the sodium the average American consumes comes from the shaker. Another ten percent occurs naturally in foods. By far, the most comes from processed foods.

And it's not even salty-tasting foods like potato chips and french fries that do the most damage. At McDonald's, a large order of fries has less sodium than a serving of any sandwich, biscuit, danish, hotcakes, cookies, salad dressing, or apple pie.

Want to really avoid salt? Watch out for most brands of frozen dinners or pizza, processed meat (like hot dogs or bacon), processed (American-style) cheese, canned or dried soup, salad dressing, canned meats, beans, or vegetables, tomato sauce, restaurant and fast food, and...whew!

At least some companies are now helping. A decade ago, manufacturers said people wouldn't eat frozen dinners and canned soups if the sodium were much below 1,000 mg. Then along came Healthy Choice, and suddenly it became possible to slice that number by at least a half.

As for that shaker, why not fill it with herbs or use a squeeze of fresh lemon juice instead?

The only way to treat high blood pressure is with drugs.

The National Heart, Lung and Blood Institute urges physicians to "vigorously encourage their [high blood pressure] patients to adopt...lifestyle modifications."(7)

That means not just cutting sodium, but losing weight (especially around the waist); limiting alcohol to no more than two drinks a day; doing regular aerobic exercise; and getting adequate amounts-- that is, the Recommended Dietary Allowance (RDA)---of potassium, calcium, and magnesium (though the evidence is not conclusive that the minerals will help).

1 British Medical journal 302:811-824, 1991.

2 New Zealand Medical Journal 103: 120, 1990.

3 Journal of Nutrition 123: 1615, 1993.

4 New England Journal of Medicine 325:1170, 1991.

5 Journal of the National Cancer Institute Monographs 12: 75, 1992.

6 Nutrition and Cancer 13: 19, 1990.

7 Archives of Internal Medicine 153: 154, 1993.

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