Salt substitutes have a consistent and beneficial blood pressure-lowering effect across populations and geographies. Protective effects on clinical outcomes that are blood-pressure mediated are likely generalizable across population subgroups, and salt substitutes should be considered in clinical practice and public health policy as a viable strategy to reduce blood pressure and prevent adverse cardiovascular events. These findings were published in BMJ Heart.
Researchers aimed to assess salt substitutes effects and consistency of previous findings and to explore their generalizability. They conducted a meta-analysis of 21 trials identified in the PubMed, Cochrane Library, and Embase databases through August 2021 that included 31,949 participants. Among these trials, 5 reported effects on clinical outcomes and 19 reported effects on blood pressure. Consistency of findings across trials and patient groups was defined using meta-analysis and metaregressions.
The researchers found that the overall reduction of diastolic blood pressure (DBP) was -1.61 mm Hg (95% CI, -2.42 to -0.79), and they found the overall reduction of systolic blood pressure (SBP) was -4.61 mm Hg (95% CI, -6.07 to -3.14). Consistency of reductions was observed across geographic areas and populations defined by sex, age, body mass index, history of hypertension, baseline 24-hour urinary potassium, baseline 24-hour urinary sodium, and baseline blood pressure (all P homogeneity >.05).
Salt substitutes showed protective effects against cardiovascular events (risk ratio [RR], 0.89; 95% CI, 0.85-0.94), total mortality (RR, 0.89; 95% CI, 0.85-0.94), and cardiovascular mortality (RR, 0.87; 95% CI, 0. 81-0.94).
Each 10% lower proportion of sodium chloride in each salt substitute was associated with a -0.95 mm Hg (95% CI, -1.78 to -0.12; P =.025) greater reduction in DBP, and a -1.53 mm Hg (95% CI, -3.02 to -0.03; P =.045) greater reduction in SBP when assessed with metaregression.
Study limitations include missing data for several studies and a reporting bias for DBP. Grey literature is not included in the search and there is no observational data for salt substitutes for comparison with trials.
“Salt substitutes produce consistent blood pressure-lowering effects across geographies and diverse participant subsets,” the researchers wrote. “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.”
Yin X, Rodgers A, Perkovic A, et al. Effects of salt substitutes on clinical outcomes: a systematic review and meta-analysis. Heart. Published online August 9, 2022. doi:10.1136/heartjnl-2022-321332