Abstract
BACKGROUND: Excessive salt intake is a known cardiovascular disease (CVD) risk factor, but the health impacts of both high and low sodium intake remain debated. This study synthesize meta-analytic evidence on dietary salt intake and cardiovascular outcomes, including subgroup and dose-response analyses. METHODS: PubMed, Embase, Web of Science, and Cochrane Library were searched through August 28, 2024, for meta-analyses of randomized controlled trials and observational studies. RESULTS: 21 meta-analyses comprising 91 outcomes were included. Low sodium intake was associated with reduced risks of CVD mortality (RR = 0.83, 95% CI: 0.73-0.95), stroke mortality (RR = 0.74, 95% CI: 0.57-0.95), and all-cause mortality (RR = 0.88, 95% CI: 0.82-0.93), as well as systolic blood pressure (MD = -3.39 mmHg) and diastolic blood pressure (MD = -1.54 mmHg), improved vascular elasticity, and increased heart rate. Urinary sodium excretion and Na/K ratio decreased, while urinary potassium, calcium, and serum potassium increased. No adverse effects on lipid profiles were observed. High salt intake was associated with increased risks of CVD (RR = 1.13, 95% CI: 1.06-1.20), hypertension (OR = 1.33, 95% CI: 1.24-1.42), stroke (OR = 1.34, 95% CI: 1.19-1.51), and stroke mortality (OR = 1.40, 95% CI: 1.21-1.63). Each 1 g/day sodium increase raised systolic blood pressure by 0.60 mmHg and CVD and stroke risks by 4% and 6%, respectively. CONCLUSION: High salt intake increases cardiovascular risk, while moderate reduction provides protective benefits without adverse lipid effects. Tailored strategies are needed based on regional, sex-specific, and methodological differences.