Sodium

The Latest Shake
A salt shaker is usually nearby whenever food is served, and next to sugar, we add more salt to our food than any other condiment. Salt, which usually refers to table salt, is a chemical compound called sodium chloride. Both sodium and chloride are essential for life. Our health, however, can be maintained with as little as one-tenth of a teaspoon of salt per day. By contrast, an American's average daily intake is 10 to 35 times that amount.

Where does all that salt in our diet come from? It turns out that about 10 percent is naturally present in food, 15 percent is added during cooking and at the table, while a whopping 75 percent comes from processed foods.

We must also factor in the scientific evidence that too much dietary sodium is associated with the risk of high blood pressure. Although the connection between salt and high blood pressure may not be an issue for everyone, there are good reasons to moderate our intake of salt and the sodium it contains.

Why Is There So Much Sodium in Processed Food?
Food manufacturers find salt attractive for several reasons. Besides its role as a flavor enhancer, salt can retard the growth of a variety of microorganisms. In fact, in the days before refrigeration, salting was the only practical way to keep meats and fish from spoiling.

Salt also plays a role in food texture. Processed meats such as bologna, frankfurters, and luncheon meats contain high levels of salt because it helps form and maintain the gel-like consistency. Salt is also abundant in tomato-based products, such as spaghetti and pizza sauce or tomato juice, and it is used widely in cheese and prepared soups.

The Link with High Blood Pressure
Hypertension, or high blood pressure, currently affects about 60 million people in the United States. It is called the silent killer because there are no warning signs until problems such as heart disease, stroke, or kidney disease have already developed. The only real way to detect hypertension is to have your blood pressure checked.

The connection between salt and hypertension was suggested after several population studies compared salt intake with blood pressure. Scientists found that hypertension was rare in societies with a low-salt diet, while in societies with a high-salt diet, hypertension was more common. This finding, along with those from several animal studies, led to a public health policy to lower salt in our diet.

There is some logic to this association. The body rids itself of excess sodium via the urine, but there is an upper limit to how much salt a given amount of urine can contain. The body responds to a high salt intake by increasing our thirst, the added water being needed to dilute the sodium to get it out of the body. (That, by the way, is why drinking ocean salt water actually makes us more thirsty.) It may be that the increased blood volume brought about by a high-salt intake contributes to the higher blood pressure.

To Salt or Not?
Unfortunately, science has not yet come up with a way to predict who gets hypertension. The other complicating factor is that not everyone who has hypertension is what's called a "salt-sensitive hypertensive," meaning that their blood pressure goes up or down with their intake of dietary sodium. At present it's known that there is a strong genetic component and that African-Americans are more likely to develop high blood pressure than European-Americans. Therefore, the key is to routinely check your blood pressure, particularly if you are black or obese, have a high alcohol consumption, or tend to be inactive.

If you are at high risk, or are uncertain about your blood pressure, keep your intake of sodium to a minimum. Avoid reaching for the salt before you taste your food. Saltiness is one of our basic tastes, and salt can help bring out the flavor in food. The key, however, is to enjoy the natural flavor of food, not that which sits in the salt shaker.

The recommended upper limit of sodium for adults and children more than 4 years of age is 2,400 milligrams per day.

More on: Nutritional Resources for Families

Excerpted from:

From The Nutrition Doctor's A-to-Z Food Counter. Copyright © Ed Blonz, 1999. Used by arrangement with NAL Signet, a member of Penguin Group (USA) Inc.

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