Challenging the Salt Paradigm: A Systematic Review and Meta-Analysis of Dietary Sodium Impact on Cardiovascular Risk (original) (raw)

Background: The relationship between dietary sodium intake and Cardio Vascular Disease (CVD) risk has been a subject of ongoing debate. While previous guidelines recommended stringent sodium restriction, recent evidence suggests that moderate sodium intake may not be as harmful as previously thought. This meta-analysis aims to provide an updated assessment of the effects of sodium intake on blood pressure and cardiovascular disease risk by analyzing data from Randomized Controlled Trials (RCTs) and prospective cohort studies published between 2001 and 2016 to provide an updated perspective on the cardiovascular effects of varying levels of sodium intake. Methods: We conducted a systematic search of PubMed, Embase, and Cochrane databases for RCTs and prospective cohort studies published between January 2001 and December 2016, investigating the association between dietary sodium intake and cardiovascular outcomes. Study selection, data extraction, and risk of bias assessment were performed independently by two reviewers following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Random-effects meta-analyses were conducted to estimate the pooled Risk Ratios (RRs) and 95% Confidence Intervals (CIs) for CVD events, stroke, and all-cause mortality across different levels of sodium intake. Results: A total of 20 studies, including 585,610 participants, were included in the meta-analysis. Among these, 6 were Randomized Controlled Trials (RCTs) [1-6] and 14 were prospective cohort studies [7-17]. RCTs, which included a total of 135,494 participants, showed that reduced sodium intake was associated with a significant decrease in systolic blood pressure (Weighted Mean Difference [WMD]: -4.18 mmHg, 95% CI: -5.08 to -3.29, I2 = 68%) and diastolic blood pressure (WMD: -2.06 mmHg, 95% CI: -2.67 to -1.45, I2 = 52%) compared to higher sodium intake [1-6]. However, the 14 prospective cohort studies, which included a total of 450,116 participants, yielded different results. Moderate sodium intake (2,300-4,600 mg/ day) was not associated with an increased risk of cardiovascular disease (Relative Risk [RR]: 1.02, 95% CI: 0.93 to 1.11, I2 = 41%) compared to lower sodium intake [7-17]. Higher sodium intake (>4,600 mg/day) was associated with a slightly increased risk of cardiovascular disease (RR: 1.12, 95% CI: 1.02 to 1.24, I2 = 37%) [18,19]. The contrasting findings between RCTs and prospective cohort studies suggest that the relationship between sodium intake and cardiovascular health may be more complex than previously thought. While RCTs demonstrate the blood pressure-lowering effects of sodium reduction in the short term, the lack of a clear association between moderate sodium intake and cardiovascular disease risk in long-term prospective cohort studies raises questions about the benefits of aggressive sodium restriction in the general population. These results highlight the need for a more nuanced approach to dietary sodium recommendations, taking into account an individual’s cardiovascular risk profile and comorbidities. Future research should focus on identifying optimal sodium intake levels for different populations and investigating the long-term effects of sodium intake on cardiovascular health. Conclusions: This meta-analysis suggests that while moderate sodium reduction may lower blood pressure, it does not significantly reduce the risk of CVD events, stroke, or all-cause mortality compared to high sodium intake. The findings support the notion that moderate sodium intake may not be as harmful as previously thought and challenge the current recommendations for aggressive sodium restriction and suggest that a more nuanced approach to dietary sodium intake may be warranted.