Dietary salt reduction in hypertension - What is the evidence and why is it still controversial?

The link between sodium intake and hypertension remains controversial because of inconsistency between early epidemiologic studies, which showed a strong positive relationship between salt intake and blood pressure/incidence of hypertension, and more recent studies, which showed only modest decreases in blood pressure with sodium reduction, particularly in the normotensive population. In addition, there is clinical evidence that sodium is related to target organ damage such as left ventricular hypertrophy and renal disease. Although the evidence available linking sodium intake and blood pressure in the general population is weak, sodium reduction has been shown to be useful in hypertensive patients, particularly salt-sensitive patients. Whether dietary sodium reduction should be recommended for the general population remains questionable because of marginal benefit and the suggestion of possible deleterious effects on cardiovascular outcomes independent of blood pressure. This paper will review the definition and methods used in determining salt sensitivity, the evidence linking sodium intake and target organ damage, and modern studies of salt and blood pressure.