Salt. It's a simple compound made up of sodium and chloride, yet its value to humans dates back to the beginnings of mankind. Aside from its vital importance to the body, salt has played other fundamental roles in many civilizations: as a currency, as one of our first medicines and as a traditional symbol of social status. For example, the word "salary" is derived from the Roman word for "salt rations." A good Greek slave was said to be "worth his weight in salt," and being seated "above the salt" at the European dinner table signaled your place of honor as a guest.

Salt's culinary roles throughout history have been just as diverse as its social roles. Salt has served as a flavor enhancer, a preservative, a processing agent, a binding agent and a controlling agent in fermentation and leavening. Modern food manufacturing relies on salt for many of those functions, making processed foods generally higher in sodium than fresh or freshly prepared foods.

The sodium/blood-ressure link

Despite its prominent place in our culture, for many years nutrition experts and health authorities have recommended that people watch their salt intake in order to decrease their consumption of sodium. Most of us have heard over the years that research has linked excessive consumption of salt to hypertension, or high blood pressure, and its potentially fatal consequences, such as heart and kidney disease, and stroke.

What's the mechanism involved? The balance of water and sodium in the body must remain relatively stable for optimum metabolic function. The body constantly adjusts according to the current situation by making you thirsty when it needs extra water to dilute the salt. Thirst isn't the only way the body's sodium/fluid balance is regulated; the kidneys help, too. When the body has too much sodium, the kidneys dump it out. When the body needs sodium, the kidneys collect it and return it to the blood.

People develop high blood pressure when, for some reason, the kidneys fail to rid the body of enough sodium. The extra sodium attracts water and causes the blood volume to increase. At the same time, the blood vessels can become waterlogged and contract. Since more blood now has to pass through the narrower vessels, the blood pressure increases.

According to the National Institutes of Health (NIH), located in Bethesda, Maryland, for people with special susceptibility, a strong positive relationship between sodium intake and blood pressure has long been recognized. In other words, when sodium intake rises, so does blood pressure and the risk of hypertension. This susceptibility is found particularly among certain population segments, such as African-Americans, senior citizens and people with a family history of hypertension.

How much is too much?

Where salt is readily available, the vast majority of the world's population chooses to consume about 6 to 11 grams a day, or 2,400 to 4,400 milligrams of sodium. The National Academy of Sciences in Washington DC, recommends that Americans consume a minimum of 500 milligrams of sodium per day, which equals a little less than one-quarter of a teaspoon of salt.

Most Americans consume a lot more sodium (mostly in the form of salt) than is required for proper body functioning. Roughly 75 percent of that sodium comes from food processing and preparation (including home-prepared and restaurant foods). According to the Salt Institute, in Alexandria, Virginia, on average, Americans consume 8.75 grams of salt per day, or about 3,500 milligrams of sodium, with men consuming more than women.

The NIH recommends that people consume 2,400 milligrams or less of sodium per day; the American Heart Association (AHA) suggests no more than 3,000 milligrams each day; the National Academy of Sciences' 1990 Diet and Health Report recommends 2,400 milligrams; and even the Food and Drug Administration's Nutrition Facts Label lists the daily value for sodium at 2,400 milligrams.

The U. S. Department of Agriculture's 1995 Dietary Guidelines for Americans notes that most of us get more sodium than we need and recommends that consumers "choose a diet moderate in sugars, salt and sodium," but does not name a specific amount of sodium.

"There is no consensus on what constitutes a 'safe and adequate' level of dietary sodium," says David McCarron, professor of medicine at the Oregon Health Sciences University in Portland. "Although I wouldn't call it a recommendation, in general I believe an intake of 3,000 to 4,000 milligrams of sodium per day would be considered adequate to meet the body's needs and not be excessive for people with normal blood pressure."

Questioning salt restriction for all

So does this mean everyone has to put down the salt shaker for good? Salt restriction can reduce the blood pressure of some hypertensive persons, but salt in and of itself has never been shown to cause hypertension. Salt restriction can be effective dietary therapy for hypertension in salt-sensitive people, but according to experts, only about 30 to 35 percent of the general population is salt-sensitive. In other words, about one-third of people with normal blood pressure will see their blood pressure rise in response to increased sodium intake.

In contrast, about 50 percent of hypertensive people are believed to be salt-sensitive, probably owing to a genetic condition. But because of a lack of accurate salt-sensitivity predictors, experts have adhered to the better-safe-than-sorry theory and recommended that everyone watch their sodium intake.

However, some recent studies have called into question the efficacy and even the safety of universal sodium restriction. Intersalt, the largest and most comprehensive study on the subject so far, was conducted in 1988. The study looked at the connection between sodium intake and hypertension, and included more than 10,000 subjects from 32 countries around the world. Although the interpretation of the study's results is controversial, some experts believe that the data show that sodium intake has little to do with hypertension in Western countries. Others believe it supports moderate sodium restriction.

This year, University of Toronto researchers analyzed numerous studies in a Journal of the American Medical Association article to evaluate whether restriction of dietary sodium lowers blood pressure in hypertensive and normotensive (people with normal blood pressure) individuals. The conclusion? Restricting sodium did have an effect on the people with hypertension, especially older ones, but in effect was insignificant in people with normal blood pressure.

Other studies, including a New England Journal of Medicine article in 1991, have tied sodium restriction to a number of undesirable outcomes, including raising blood pressure in a certain proportion of patients and contributing to sleep disturbances and even heart attacks in men with pre-existing hypertension. Keep in mind, however, that those studies have not proven that too little sodium causes the problems, just that there is an association.

Despite continuing research on sodium and blood pressure, the controversy over sodium reduction continues. Nevertheless, most major health authorities continue to recommend moderate sodium reduction. For example, the National Heart, Lung and Blood Institute (NHLBI), located in Bethesda, Maryland, which advocates sodium reduction for hypertensives, as well as the general public, suggests that people limit salt intake to 6 grams per day — about 1 teaspoon, which is equal to 2,400 milligrams of sodium.

"The preponderance of data supports modest sodium reduction down to 2,400 milligrams [daily]. This is not a level low enough to cause adverse health effects, and in fact, we believe that this small reduction over a long period of time will yield important public health benefits," says Ed Roccella, coordinator of NHLBI's National High Blood Pressure Education Program.

According to some experts, it's very likely that the direction of future research won't focus just on sodium, but rather on the balance of sodium and other electrolytes, such as potassium, calcium and magnesium, as well as on other lifestyle factors. McCarron explains that in the absence of a concrete consensus on the issue, the best approach may be to maintain the proverbial "moderation in all things" approach.

"Instead of concentrating all efforts on dietary sodium reduction, people who are interested in reducing their blood pressure or risk of hypertension should practice lifestyle and dietary changes which are known to work: losing excess weight and watching alcohol intake. Eating a nutritious diet that contains a moderate amount of sodium would also be prudent," adds McCarron.

Satisfying customers — without salt

Although restaurateurs around the country say they have not seen an increase in requests for sodium-free menu items, they remain prepared to satisfy diners who must restrict their salt intake.

Raymond Badach, the owner of Restaurant 28 in Montclair, New Jersey, estimates that sodium requests comprise only about 2 percent of the establishment's special requests. Despite the relative rarity of such requests, it's important to realize that some health problems — such as kidney problems — still require strict sodium monitoring, and customers who suffer from them will always be concerned about the sodium content of their meals.

For many chefs, simply altering an existing recipe in order to lower sodium is the most practical way to satisfy customers' requests without going to the trouble of creating a separate "low sodium" menu. The never-ending challenge when creating lower-sodium recipes is to still provide a satisfying, flavorful meal.

At Restaurant 28, chef Bruce Johnson relies on a few highly flavorful oils and sauces to spice up many of his signature dishes, as well as his sodium-reduced creations. "I like to create intense, true flavors using just a few good-quality ingredients. Reducing balsamic vinegar or red wine to syrups and combining vegetable-juice reductions with fresh herb oils are a couple of my favorite ways to deliver a big flavor impact without a lot of salt," says Johnson.

Altering the actual cooking method is another way to reduce sodium, according to Kerry Heffernan, executive chef at The Polo in Manhattan's Westbury Hotel. "Very often, when a customer wants a lower-sodium version of a roasted menu item, I simply slice and grill the meat or vegetables," says Heffernan. "Grilled food has a nice flavor of its own, and using a rub, flavored oil or fresh herbs gives the flavor an extra boost."

While there is no need to remove all the salt shakers from dining-room tables or from the kitchen, operators who provide low-sodium menu choices, such as the ones mentioned here, show a desire to satisfy their guests' needs — a gesture that will surely impress all diners.

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