Oral Potassium Supplementation Lowers Clinic Blood Pressure in Untreated Primary Hypertension-Systematic Review and Meta-Analysis of Randomized Trials.

BACKGROUND: Potassium may lower blood pressure (BP), but its effect in untreated primary hypertension remains uncertain. METHODS: We systematically reviewed randomized parallel or crossover trials in adults with untreated primary hypertension comparing oral potassium supplementation with placebo, sodium chloride, or no treatment. The review was prospectively registered in PROSPERO (International Prospective Register of Systematic Reviews; CRD42024621287). PubMed, Embase, Cochrane Central Register of Controlled Trials, Scopus, Cumulative Index to Nursing and Allied Health Literature, and trial registries were searched through January 31, 2025 and updated October 1, 2025. End-of-treatment between-group mean differences were pooled using inverse-variance common-effect models; random-effects models were sensitivity analyses. Risk of bias, missing-evidence bias, and certainty were assessed using Cochrane Risk of Bias 2 tool, Risk of Bias Due to Missing Evidence, and Grading of Recommendations Assessment, Development and Evaluation. RESULTS: Nineteen trials (803 participants; 14 crossover, 5 parallel; median duration, 4 weeks) were included. Potassium reduced clinic systolic BP by 5.3 mm Hg (95% CI, 4.4-6.3) and diastolic BP by 4.5 mm Hg (95% CI, 3.9-5.1). Reductions in 24-hour ambulatory BP were smaller: 2.8 mm Hg (95% CI, 1.3-4.3) systolic and 3.2 mm Hg (95% CI, 2.2-4.2) diastolic. Adverse events were more frequent with potassium (12.8% versus 3.2%), whereas withdrawals and adverse-event withdrawals were uncommon. Heterogeneity was substantial, and ambulatory BP evidence was limited. CONCLUSIONS: In untreated primary hypertension, oral potassium supplementation modestly reduces clinic BP and may produce smaller reductions in 24-hour ambulatory BP. Heterogeneity, short follow-up, and limited ambulatory and safety data warrant cautious interpretation. REGISTRATION: URL: PROSPERO; Unique Identifier: CRD42024621287.