Link between salt and hypertension clarified

A new US review shows that salt raises blood pressure, but through the action of adrenaline, rather than blood volume expansion as originally believed.

Through a review of numerous studies, the researchers demonstrated that the mechanism of hypertensionresulting from the excessive consumption and retention of sodium chloride (salt) stimulates the sympathetic nervous system in the brain, increasing adrenaline production (1). The increased levels of adrenalin circulating throughout the body cause the arteries to constrict, which results in resistance to blood flow and a decrease in circulatory volume.

The overactivation of the sympathetic nervous system – part of the autonomic nervous system that helps maintain the body’s homeostasis – has been recognized clinically as a characteristic of hypertension that accompanies renal failure, which is the most typical reason for elevated blood pressure from excessive salt retention. <acronym title=">Diuretics, which remove excess salt, are widely used to treat this type of hypertension. However, this study provides convincing evidence that the sympathetic nervous system should be the focus of further investigations into treatments for hypertension.

The researchers commented that these results correct an erroneous concept that has prevailed for many years, despite the scientific evidence that has mounted against it. The implication of the findings is that the optimal treatment for hypertension, for cases associated with renal failure, should not only include diuretics but also the use of drugs that block the central sympathetic nervous system.

1. Gavras I. and Gavras H. “Volume-expanded” hypertension: the effect of fluid overload and the role of the sympathetic nervous system in salt-dependent hypertension. J Hypertens. Published online February 2012.