Salt affects organs

http://www.eurekalert.org/pub_releases/2015-03/uod-sao031015.php

Public Release: 10-Mar-2015
University of Delaware

You may think you're one of the lucky ones who can eat all the salty snacks and convenience foods you want and still register low numbers on the blood pressure cuff. But, new research suggests you may not be so lucky after all.

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.

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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.

They review their work and the growing body of evidence to support a deleterious effect of dietary salt on vascular function independent of blood pressure in a recent invited paper in Current Opinion in Nephrology and Hypertension.

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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.

"Chronically elevated dietary sodium may 'sensitize' sympathetic neurons in the brain, causing a greater response to a variety of stimuli, including skeletal muscle contraction," Farquhar says. "Again, even if blood pressure isn't increased, chronically increased sympathetic outflow may have harmful effects on target organs."

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