THERE are considerable data which indicate that the sodium ion is important or necessary for the development of certain types of experimental hypertension.* So far, to our knowledge, no evidence has been published to suggest that a similar relationship exists with so-called "essential" hypertension in man. A statistical analysis of the data to be presented in this paper, however, indicates that there is a significant correlation between sodium chloride intake and the development of hypertension in man. While the effects of sodium and chloride could not be separated in this study, all the experimental evidence indicates that the sodium ion alone is important, and our interest has centered solely about that ion.
For some years one of us has been intrigued by the lack of significant numbers of persons with hypertension among truly primitive human races. Recently Bays and Scrimshaw 7 have suggested that this may not be uniformly so.