Dietary sodium and blood pressure.

Abstract

The importance of dietary sodium chloride in the regulation of blood pressure has received much attention over the past few years. This area of research and knowledge has been controversial for several reasons. The major reason for controversy is that the science of the relationship is difficult to ascertain. Population science is limited by the narrow range of dietary sodium intake by most populations and individuals and the multiple confounders in those populations at the extremes of intake. Results from clinical trials have been difficult to interpret because of the difficulty in maintaining a given level of sodium intake over a period of time sufficient for study. Furthermore, basic science studies have been challenged by identifying appropriate models that mimic salt-sensitive hypertension in humans. Moreover, a lack of a well-funded proponent in industry complicates the research challenges. Guyton’s concept that the role of the kidney in handling sodium is key to the long-term regulation of blood pressure is now generally accepted.1 However, the exact role that dietary sodium plays in this relationship remains controversial. The relationship between renal handling of sodium and blood pressure is apparently influenced by a complex combination of factors including nutritional, other environmental, genetic, neurohormonal, and metabolic factors. The skepticism of many regarding the role of dietary sodium in blood pressure regulation and control has been tempered by the results of the DASH sodium study.2 Most acknowledge that this study reliably confirmed the benefit of dietary sodium restriction in blood pressure management. The study showed a dose-dependent impact of dietary sodium restriction on blood pressure in older hypertensive and nonhypertensive subjects. For many interested in this area of research, the questions have shifted as a result of the DASH sodium study. Rather than questioning whether dietary sodium is important, many investigators have turned their …