Sodium plays a vital role in our health. Although no one knows for certain, scientists estimate the body requires 250 to 500 milligrams (mg) each day for basic physiologic functions. "We need salt to transport nutrients, transmit nerve impulses, and contract muscles, including your heart," says Anna Di Rienzo, Ph.D., associate professor of human genetics at the University of Chicago. But when sodium levels are too high, the kidneys release more water, increasing blood volume. With more blood flowing through the body, pressure increases. Over time, a sustained pressure increase causes the heart to work harder to pump blood and threatens the stability of blood vessels, which raises the risk of heart disease and stroke.
This physiological chain of events prompted the experts behind the 2005 revised Dietary Guidelines for Americans to reduce the recommendations for sodium intake from 2,400mg per day to an upper limit of 2,300mg for adults. "These recommendations are immensely important for everyone, but especially for those predisposed to develop hypertension [high blood pressure], especially African Americans, obese people, and those with a family history of hypertension, stroke, or heart disease," says Julius Linn, M.D., member of the Cooking Light advisory board and executive director of medical publications at the University of Alabama at Birmingham. Yet the recommended figure is nearly half what the average American consumes daily, according to the Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey.
How Your Daily Sodium Intake Measures Up
Daily sodium needed for basic physiological functions:
scant 1/8 tsp = 250mg sodium
Daily sodium limit for seniors:
1/2 tsp salt = 1,200mg sodium
Daily sodium limit for adults:
scant 1 tsp salt = 2,300mg sodium
Daily sodium the average American consumes:
heaping 1 1/2 tsp = 4,000mg sodium
Salt vs. Sodium
Though we tend to swap "salt" and "sodium" as if the two words were interchangeable, there is a difference. Table salt is actually sodium chloride, explains Ilene Smith, R.D., M.S., associate director of Ketchum's Food and Nutrition Group. It's 40 percent sodium and 60 percent chloride.
Very little of the sodium we consume arrives in our diets via saltshakers. The majority-75 percent-comes from processed foods, where it enhances flavor, stabilizes, or preserves, Smith says. There are the usual high-sodium sources: bacon, ham, sausage and other cured meats; frozen or boxed entrées; frozen and canned vegetables; fast foods; and sauces and salad dressings. But sodium also hides in unexpected places. For example, cottage cheese can contain almost 1,000mg per cup. Read labels to find good choices.