Umbrella review synthesizes evidence on potassium-containing low-sodium salt substitutes for blood pressure and cardiovascular outcomes

Potassium-containing low-sodium salt substitutes (LSSS) may lower sodium intake, increase potassium intake, and reduce cardiovascular risk in mixed adult populations, but the review literature is overlapping and methodologically heterogeneous. This umbrella review assessed the efficacy, safety, and evidence quality of potassium-containing LSSS for blood pressure, cardiovascular outcomes, and adverse events. Following a registered PROSPERO protocol (CRD420261294404), we searched PubMed, Embase, Web of Science, Global Health (EBSCO) and the Cochrane Database of Systematic Reviews from inception to 6 March 2026 for systematic reviews, meta-analyses and umbrella reviews of potassium-containing LSSS. Eleven reviews met eligibility criteria. Methodological confidence was high in one review, moderate in three, low in five and critically low in two. Primary study overlap was very high (corrected covered area 28.5%). Review-level pooled estimates consistently favoured potassium-containing LSSS for systolic blood pressure (mean differences -4.61 to -8.87 mmHg) and diastolic blood pressure (-1.42 to -4.04 mmHg). Later reviews also reported lower all-cause mortality (RR 0.88 - 0.89), cardiovascular mortality (RR 0.72 - 0.87), composite cardiovascular events and selected stroke outcomes; however, clinical-outcome estimates were heavily influenced by the Salt Substitute and Stroke Study. Serum potassium changed minimally (-0.02 to 0.18 mmol/l), and pooled estimates for hyperkalaemia and serious adverse events showed no clear excess risk in trial populations that largely excluded participants at higher risk of impaired potassium handling. Potassium-containing LSSS consistently lower blood pressure and may improve cardiovascular outcomes, but further trials are needed outside Eastern Asia, with clearer formulation reporting, prespecified baseline CVD-history strata, and stronger safety data in higher-risk populations.