Salt. A perpetrator of hypertensive target organ disease?

Experimental and clinical data suggest salt intake to be an important factor in the pathogenesis of essential hypertension. However, the relationship between dietary sodium and blood pressure has been found to be relatively weak, perhaps because causal blood pressure levels fluctuate considerably. We hypothesized that a closer correlation could be expected between salt intake and the degree of hypertensive target organ disease. We reviewed the literature for studies dealing with 24-hour urinary sodium excretion (as a measure of salt intake) and hypertensive target organ disease as assessed by left ventricular structure and function, microproteinuria, cerebrovascular disease, and arterial compliance. Salt intake as assessed by 24-hour urinary sodium excretion was found to be a close independent determinant of left ventricular mass in 9 different studies worldwide. A reduction in dietary sodium has been shown to reduce left ventricular hypertrophy. There is clinical and experimental evidence, particularly in salt-sensitive patients, that salt intake directly affects hypertensive renal disease, cerebrovascular disease, and compliance of large arteries. The close and partially independent correlation between salt intake and hypertensive target organ disease suggests dietary sodium to be a direct perpetrator of cardiovascular disease.