Effect of dose and duration of reduction in dietary sodium on blood pressure levels: systematic review and meta-analysis of randomised trials

Abstract

ObjectiveTo examine the dose-response relation between reduction in dietary sodium and blood pressure change and to explore the impact of intervention duration.DesignSystematic review and meta-analysis following PRISMA guidelines.Data sourcesOvid MEDLINE(R), EMBASE, and Cochrane Central Register of Controlled Trials (Wiley) and reference lists of relevant articles up to 21 January 2019.Inclusion criteriaRandomised trials comparing different levels of sodium intake undertaken among adult populations with estimates of intake made using 24 hour urinary sodium excretion.Data extraction and analysisTwo of three reviewers screened the records independently for eligibility. One reviewer extracted all data and the other two reviewed the data for accuracy. Reviewers performed random effects meta-analyses, subgroup analyses, and meta-regression.Results133 studies with 12 197 participants were included. The mean reductions (reduced sodium v usual sodium) of 24 hour urinary sodium, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were 130 mmol (95% confidence interval 115 to 145, P<0.001), 4.26 mm Hg (3.62 to 4.89, P<0.001), and 2.07 mm Hg (1.67 to 2.48, P<0.001), respectively. Each 50 mmol reduction in 24 hour sodium excretion was associated with a 1.10 mm Hg (0.66 to 1.54; P<0.001) reduction in SBP and a 0.33 mm Hg (0.04 to 0.63; P=0.03) reduction in DBP. Reductions in blood pressure were observed in diverse population subsets examined, including hypertensive and non-hypertensive individuals. For the same reduction in 24 hour urinary sodium there was greater SBP reduction in older people, non-white populations, and those with higher baseline SBP levels. In trials of less than 15 days’ duration, each 50 mmol reduction in 24 hour urinary sodium excretion was associated with a 1.05 mm Hg (0.40 to 1.70; P=0.002) SBP fall, less than half the effect observed in studies of longer duration (2.13 mm Hg; 0.85 to 3.40; P=0.002). Otherwise, there was no association between trial duration and SBP reduction.ConclusionsThe magnitude of blood pressure lowering achieved with sodium reduction showed a dose-response relation and was greater for older populations, non-white populations, and those with higher blood pressure. Short term studies underestimate the effect of sodium reduction on blood pressure.Systematic review registrationPROSPERO CRD42019140812.

Dietary Sodium Intake and Risk of Cardiovascular Disease: A Systematic Review and Dose-Response Meta-Analysis

“…In patients with high BP, the mean change in urinary sodium excretion was 75 mmol per 24 h, with a mean reduction of 4.18 mmHg in systolic BP and 2.06 mmHg in diastolic BP [ 10 ]. These results were in agreement with two meta-analyses [ 11 , 12 ]. Indeed, in a dose-response meta-analysis performed by Graudal et al, a significant relationship between sodium reduction and BP was observed in the highest 25th percentile of the population [ 11 ].…”

“…Indeed, in a dose-response meta-analysis performed by Graudal et al, a significant relationship between sodium reduction and BP was observed in the highest 25th percentile of the population [ 11 ]. Furthermore, Huang et al and colleagues conducted a meta-analysis to evaluate the effect of dietary sodium reduction on BP [ 12 ]. The study demonstrated a dose-response relationship between BP and sodium reduction, especially in participants with high BP.…”

Sodium and health—concordance and controversy

“…In addition, a meta-analysis of three trials of hypertension prevention11 suggested a 20% lower incidence of hypertension among those in a sodium reduction intervention. Overall, there seems to be a consensus that reducing sodium has beneficial effects on blood pressure, at least among those with above average pressure 2223…”

Sodium and Potassium Intake: A New Statistical Model to Test Their Effects on Health Outcomes

“…This is an additional piece of evidence in favor of the deleterious effect of sodium intake on blood pressure among patients with chronic kidney disease while this relationship is well documented in numerous populations. 2 In this study, urinary sodium-to-potassium ratio was associated with blood pressure whereas potassium was not. It can be puzzling to conclude for the significance of a ratio when one of its components is not significant.…”