Love to munch on those salted chips? You may want to lay off them as new study claims that salt does more than just affect your blood pressure.
A review paper co-authored by two faculty members in the University of Delaware College of Health Sciences and two physicians at Christiana Care Health System provides evidence that even in the absence of an increase in blood pressure, excess dietary sodium can adversely affect target organs, including the blood vessels, heart, kidneys and brain.
One of the authors William Farquhar said that blood pressure responses to alterations in dietary sodium vary widely, which has led to the concept of 'salt-sensitive' blood pressure. There were no standardised 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.
However, the research cited in the paper points to evidence of adverse effects on multiple target organs and tissues, even for people who are salt resistant.
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.
Researchers had previously found 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, added the scientists. Regarding the kidneys, evidence suggests that high sodium is associated with reduced renal function, a decline observed with only a minimal increase in blood pressure.
Finally, sodium may also affect the sympathetic nervous system, which activates what is often termed the fight-or-flight response.
Author William Weintraub said that approximately 70% 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. 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 flavor to home-cooked meals.
The paper is published in the Journal of the American College of Cardiology.