Salt, Hypertension, and Cardiovascular Diseases

The relationship between salt and hypertension is well established, and salt restriction is widely recommended in the management of hypertension. However, people living in northeast Asia have consumed large amount of salt, and the prevalence of hypertension and the incidence of stroke have been high in that area. Mechanisms of salt-induced hypertension may be complex, but volume expansion in the presence of impaired natriuretic capacity of the kidney and action on the central nervous system and neurohormoral pathways seem to be important. Salt is also involved in changes in blood pressure (BP) caused by other factors, such as weight gain, stress, exercise, potassium, catecholamines, angiotensin, and aldosterone. The interaction between sodium and aldosterone appears to play a critical role in the development of organ damage. The depressor effect of salt restriction in hypertensive patients is well demonstrated although the response of BP varies widely among individuals. Salt restriction decreases BP throughout 24 hours, and its effect may be greater during night compared to daytime in salt-sensitive nondippers. Although excess salt consumption can cause cardiovascular diseases through its effect on BP, recent studied have shown that the association of salt consumption and cardiovascular diseases, such as stroke and heart failure, is independent of BP. Salt reduction is important in the prevention of cardiovascular diseases, however, the effect and safety of aggressive salt restriction remain to be clarified. It is difficult to accomplish and maintain the salt reduction. Both population strategy and individualized approach are important to reduce salt consumption.