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Under pressure: reducing salt intake to lower blood pressure

Does reducing salt intake actually reduce blood pressure? If so, by how much? This meta-analysis aimed to answer these questions.

Study under review: Dose-response relation between dietary sodium and blood pressure: a meta-regression analysis of 133 randomized controlled trials.

Introduction

Hypertension, or elevated blood pressure, is the most important modifiable risk factor[1] for cardiovascular disease, which remains the leading cause of death in the U.S. and other western industrialized countries. As such, blood pressure control is one of the leading targets for lowering the risk of cardiovascular disease.

Recently, several trials have shown that lowering blood pressure with anti-hypertensive medications will not only successfully lower blood pressure but also the risk of cardiovascular events. This has been found in people with[2] and without[3] diabetes, suggesting that regardless of other comorbidities, lowering blood pressure is an important aspect of reducing cardiovascular disease.

Sodium is a known regulator of blood pressure. Sodium concentrations are sensed by macula densa[4] cells in the kidneys. When the blood sodium concentration increases, these cells activate the renin-angiotensin-aldosterone system to increase blood pressure, as shown in Figure 1. Therefore, it has been hypothesized that lowering sodium intake may help reduce blood pressure in people in people with and without elevated blood pressure.

Many randomized trials have examined the effect of different levels of sodium intake and sodium restriction on blood pressure. These trials have been performed in people with hypertension and people with normal blood pressure, also called normotensive individuals. The results of these trials have yielded mixed results and a clear dose-response analysis has not yet been performed. This study was designed to explore the dose-response relationship between sodium restriction and changes in blood pressure in people with and without hypertension.

Hypertension is the leading modifiable risk factor for cardiovascular disease. Higher concentrations of sodium in the blood can increase blood pressure by activation of the renin-angiotensin-aldosterone system. The present study was a meta-regression that was designed to explore the dose-response relationship between sodium restriction and changes in blood pressure in people with and without hypertension.

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Other Articles in Issue #58 (August 2019)