Effect of Sodium Restriction on Cardiovascular Outcomes in Patients With Hypertension and Heart Failure: A Systematic Review and Meta-Analysis

Dietary sodium restriction is a cornerstone of cardiovascular disease management guideline recommendations. However, sodium restriction's impact on hard clinical endpoints in patients with heart failure remains controversial, showing conflicting results compared to the established benefits in essential hypertension. A systematic review and meta-analysis of randomized controlled trials (RCTs) and observational cohort studies evaluating the effect of sodium restriction on all-cause mortality and cardiovascular hospitalization was conducted. Databases were searched through December 2025. Random-effects models were used to pool hazard ratios (HR) with 95% confidence intervals (CI). Heterogeneity was assessed using the I2 statistic, and potential bias was evaluated using the Cochrane Risk of Bias 2 (RoB 2) tool and Newcastle-Ottawa Scale. A total of 20 studies (11 RCTs, nine observational cohorts) involving 306,019 participants were included. In RCTs, the impact of sodium restriction varied significantly by clinical population. While restriction reduced mortality risk in patients with hypertension, it showed a non-significant trend toward harm in patients with established heart failure. In observational studies, low sodium intake was associated with increased mortality risk, supporting a J-shaped relationship. These findings suggest that while sodium restriction is beneficial for hypertension, aggressive restriction in heart failure may not improve outcomes and could be detrimental. This challenges uniform guideline recommendations and highlights the urgent need for personalized dietary management. In observational studies, low sodium intake was associated with increased mortality risk (HR, 1.20 (1.05-1.38)), supporting a J-shaped relationship. Sodium restriction is beneficial for mortality reduction in hypertension but does not improve clinical outcomes in heart failure patients and may be associated with harm in restrictive (