Eat Your Fruits and Vegetables But Hold the Salt

Abstract

Humans and animals like the taste of salt. It is 1 of 5 taste sensations present on the human tongue. We developed this sense because sodium and chloride are critical to our circulatory blood volume. Numerous redundant regulatory systems also evolved to protect and preserve blood volume through sodium conservation. Article p 1563 So is too much of a good thing bad for us? During evolution, effective sodium conservation was favorable to survival when the environment was arid and food intake capricious. A surfeit of salt intake rarely occurred, until the modern era. Less evolutionary pressure existed to develop mechanisms to excrete excess salt. Thus, it became possible for too much salt intake to become detrimental. Clinical investigators such as Lewis Dahl hypothesized and then became convinced through experimentation that excess salt intake is injurious to the cardiovascular system. But, although experimental animals can be bred to develop salt intake–related changes in blood pressure, humans are a much more complex entity. Scores of studies in humans have examined the blood pressure response to salt loading and deprivation. Almost all are short term (<30 days). From these studies, the terms salt sensitivity and salt resistance arose to describe the blood pressure response to changing dietary salt. But these terms often are arbitrarily defined and applied, and no clinical tool exists that can predict a given person’s blood pressure response to changes in salt intake. National guidelines for the prevention and treatment of hypertension consistently advocate salt restriction for the general population1 on the basis of the known benefits that accrue for a given blood pressure reduction, assuming that one occurs with salt restriction. A series of meta-analyses have generally, although not always, supported this conclusion,2–4 …