New Study Shows Salt Affects Not Only the Heart

Amy Taylor March 11, 2015

Most people consume more than the daily recommended amount of sodium on a daily basis. Part of the reason why is that salt is hidden in most food products, from cereals to biscuits, canned goods, processed meats, pasta sauces, condiments and so on. And the undesirable health effects, such as increased risk of heart disease, of too much salt are not new. But according to a new study, too much salt does not only promote increase in blood pressure, but can adversely affect target organs as well, including the blood vessels, heart, kidneys and brain.

The review paper was co-authored by two faculty members in the University of Delaware College of Health Sciences and two physicians at Christiana Care Health System.

"Blood pressure responses to alterations in dietary sodium vary widely, which has led to the concept of ’salt-sensitive’ blood pressure," says William Farquhar of Christiana Care. "There are no standardized guidelines for classifying individuals as having salt-sensitive blood pressure, but if blood pressure increases during a period of high dietary sodium or decreases during a low-sodium period, the person is considered salt sensitive. If there’s no change in blood pressure with sodium restriction, an individual is considered salt resistant."

Health Risks

Researchers say potential effects on the arteries include reduced function of the endothelium, which is the inner lining of blood vessels. Endothelial cells mediate a number of processes, including coagulation, platelet adhesion and immune function. Elevated dietary sodium can also increase arterial stiffness.

Farquhar and Edwards have done previous work in this area, with one study showing that excess salt intake in humans impairs endothelium-dependent dilation and another demonstrating that dietary sodium loading impairs microvascular function. In both cases, the effects are independent of changes in blood pressure.

"High dietary sodium can also lead to left ventricular hypertrophy, or enlargement of the muscle tissue that makes up the wall of the heart’s main pumping chamber," Edwards says. "As the walls of the chamber grow thicker, they become less compliant and eventually are unable to pump as forcefully as a healthy heart."

Their review also provides evidence that high sodium is associated with reduced renal function, a decline observed with only a minimal increase in blood pressure.

Reducing the salt habit

Taking the salt shaker off the table is a good way to start, but it’s probably not enough, says Weintraub, whose work focuses on cardiology outcomes.

"Approximately 70 percent of the sodium in our diets comes from processed foods, including items that we don’t typically think of as salty such as breads and cereals," he says. "Also, restaurant food typically contains more salt than dishes prepared at home, so eating out less can help reduce salt intake, especially if herbs and spices—instead of salt—are used to add flavour to home-cooked meals."

"Reducing sodium will take a coordinated effort involving organizations like the AHA, food producers and processors, restaurants, and public policy aimed at education," Weintraub says.

Their study was published in the Current Opinion in Nephrology and Hypertension.

Source of this article: Dietary Sodium and HealthMore Than Just Blood Pressure