With a Grain of Salt

By Peggy J. Noonan

A nutritious diet can help you reach and even surpass recently lowered sodium guidelines.

Doctors call it ''the white-coat effect'': the natural rise in blood pressure that comes with exam-room anxiety. But a simple case of nerves couldn’t explain the numbers that Roger Moeller, a 60-year-old editor and publisher in Bethlehem, Connecticut, was hearing during an annual physical. Since his last visit, his systolic blood pressure—the force exerted on artery walls with each heartbeat—had jumped from 130 to 200, while his diastolic pressure—the force between heartbeats—rose from 90 to 100, placing him at serious risk for cardiovascular disease.

When his doctor advised exercise and a low-sodium diet in addition to blood pressure–managing medication, Moeller ''heeded the warning,'' he says. He began walking more than a mile per day and tried to remove excess sodium from his diet. ''There are packaged foods you would never think have a lot of sodium in them,'' he says. After three months, Moeller’s blood pressure reached 150 systolic/90 diastolic—an improvement, but still above the 120 systolic/80 diastolic that the National Heart, Lung, and Blood Institute recommends. He learned that he needed to remove even more sodium from his diet.

Grains of Truth

Ironically, 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 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.