Lowering Dietary Sodium Intake Has Dose-Response Effect on BP

Prior short-term studies may have underestimated the impact of dietary sodium reduction on blood pressure (BP), according to the authors of a new systematic review and meta-analysis. Their findings, which were published in The British Medical Journal, indicate that dietary sodium reduction has a dose-response effect on blood pressure (BP) in the long term.

This association was especially prominent among older adults, nonwhite populations, and populations with higher BP, the authors wrote.

The systematic review and meta-analysis included 133 (N=12,197) randomized trials published until January 21, 2019, that had compared different levels of sodium intake among adult populations, with estimates of intake calculated via urinary sodium excretion.

The findings of the analysis indicated that the mean reduction (reduced sodium compared with usual sodium) in 24-hour urinary sodium was 130 mmol, systolic BP was 4.26 mm Hg, and diastolic BP was 2.07 mm Hg. Furthermore, each 50 mmol reduction in 24-hour sodium excretion was associated with a 1.10 mm Hg reduction in systolic BP and a 0.33 mm Hg reduction in diastolic BP.

Of note, the BP-lowering benefits of reduced dietary sodium intake were observed among diverse population subsets in the analysis, including individuals with and without hypertension.

For the same reduction in 24-hour urinary sodium, greater reductions in systolic BP were observed among older individuals, nonwhite populations, and individuals with higher baseline systolic BP, the researchers wrote.

Notably, in trials lasting fewer than 15 days, each 50 mmol reduction in 24-hour urinary sodium excretion was associated with a 1.05 mm Hg decrease in systolic BP, which is less than half of the effect observed in studies of longer duration (2.13 mm Hg). However, no other association between trial duration and systolic BP reduction was observed.

—Christina Vogt

Reference:
Huang L, Trieu K, Yoshimura S, et al. Effect of dose and duration of reduction in dietary sodium on blood pressure levels: systematic review and meta-analysis of randomised trials. BMJ. 2020;368:m315. https://doi.org/10.1136/bmj.m315.