Salt Substitutes Linked to Lower Blood Pressure, Reduced Event and Mortality Risk

Bruce Neal, MBChB, PhD

New research is providing further evidence in support of large-scale use of salt substitutes in public health efforts to mitigate the impact of cardiovascular disease on a societal level.

Led by investigators from the landmark Salt Substitute and Stroke Study (SSaSS), results of the systematic review and meta-analysis provide an overview of the apparent reductions in blood pressure observed with use of a salt substitute as well as the impact on overall risk of mortality and mortality from cardiovascular-specific causes.

“Salt substitutes produce consistent blood pressure-lowering effects across geographies and diverse participant subsets. Blood pressure-mediated beneficial effects of salt substitute on clinical outcomes appear likely to be accrued across a broad range of populations without adverse effects,” wrote investigators.

Led by Bruce Neal, MBChB, PhD, of the George Institute for Global Health, who was also the lead investigator of the Salt Substitute and Stroke Study, the current study was launched with the intent of providing clinicians with further evidence of the effects of salt substitutes on clinical outcomes in broader population groups. To do so, investigators designed their endeavor as a systematic review and meta-analysis of parallel-group, step-wedge, or cluster randomized controlled trials evaluated the impact of salt substitutes on blood pressure or clinical outcomes.

Through a search of the PubMed, Embase and Cochrane Library databases from inception through August 31, 2021, investigators identified 21 trials encompassing 31,939 participants for inclusion in their analyses. Of the 21 trials identified for inclusion, 19 reported effects on blood pressure and 5 reported effects on clinical outcomes. For the purpose of analysis, meta-analyses and meta-regressions were used to estimate the consistency of findings across trials, geographic locations, and patient subgroups.

Upon analysis, investigators found use of a salt substitute was associated with an overall reduction of systolic blood pressure of -4.61 mmHg (95% CI, -6.07 to -3.12) and of diastolic blood pressure of -1.61 mmHg (95% CI, -2.42 to -0.79), which investigators noted appeared to be consistent regardless of geographical region and across patient subgroups defined by age, sex, history of hypertension, body mass index, baseline blood pressure, baseline 24-hour urinary sodium and baseline 24-hour urinary potassium (all P for homogeneity >.05). Using meta-regression, investigators found each 10% lower proportion of sodium chloride in the salt substitute was associated with a -0.95 mmHg (95% CI,-1.78 to-0.12; P=.025) in diastolic blood pressure and a -1.53 mmHg (95% CI, -3.02 to -0.03; P=.045) greater reduction in systolic blood pressure. In additional analyses, investigators observed clear protective effects of salt substitute use on total mortality (RR, 0.89 [95% CI, 0.85 to 0.94]), cardiovascular mortality (RR, 0.87 [95% CI, 0.81 to 0.94]), and cardiovascular events (RR, 0.89 [95% CI, 0.85 to 0.94]).

“These findings are unlikely to reflect the play of chance and support the adoption of salt substitutes in clinical practice and public health policy as a strategy to reduce dietary sodium intake, increase dietary potassium intake, lower blood pressure and prevent major cardiovascular events,” investigators added.

This study, “Effects of salt substitutes on clinical outcomes: a systematic review and meta-analysis,” was published in Heart.