Low salt diet and treatment of hypertension: an old story.

A relatively low salt intake is nowadays considered one of the characteristics of a healthy diet in the Western world because several disorders appear to be unfavorably affected by excessive salt intake with the diet. The first notion about a relation between salt intake and blood pressure traces back to 2500 bc in an ancient Chinese medical textbook. This paper focuses on studies about salt and hypertension in the first half of the 20th century. The first papers in this field were published from the beginning of the century, but due to a modest scientific content were still not considered in the 1940s to provide sufficient evidence in favor of a salt restriction in hypertensive patients. A major practical contribution came from the Kempner rice diet, an effective antihypertensive dietary treatment which included a severe restriction of salt intake. After that, several studies in animals and humans showed that, with regard to the antihypertensive effect, the key element of the Kempner diet was the low salt content. By the first years of the 1950s, the evidence was already available that salt restriction is an effective antihypertensive treatment and that adherence to the treatment should be assessed by monitoring urinary electrolytes.