OBJECTIVE: A systematic review and meta-analysis was conducted to assess the efficacy of low-sodium salt substitutes (LSSS) as a potential intervention to reduce cardiovascular (CV) diseases.
METHODS: Five engines and ClinicalTrials.gov were searched from inception to May 2018. Randomised controlled trials (RCTs) enrolling adult hypertensive or general populations that compared detected hypertension, systolic blood pressure (SBP), diastolic blood pressure (DBP), overall mortality, stroke and other CV risk factors in those receiving LSSS versus regular salt were included. Effects were expressed as risk ratios or mean differences (MD) and their 95% CIs. Quality of evidence assessment followed GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology.
RESULTS: 21 RCTs (15 in hypertensive (n=2016), 2 in normotensive (n=163) and 4 in mixed populations (n=5224)) were evaluated. LSSS formulations were heterogeneous. Effects were similar across hypertensive, normotensive and mixed populations. LSSS decreased SBP (MD -7.81 mm Hg, 95% CI -9.47 to -6.15, p<0.00001) and DBP (MD -3.96 mm Hg, 95% CI -5.17 to -2.74, p<0.00001) compared with control. Significant increases in urinary potassium (MD 11.46 mmol/day, 95% CI 8.36 to 14.55, p<0.00001) and calcium excretion (MD 2.39 mmol/day, 95% CI 0.52 to 4.26, p=0.01) and decreases in urinary sodium excretion (MD -35.82 mmol/day, 95% CI -57.35 to -14.29, p=0.001) were observed. Differences in detected hypertension, overall mortality, total cholesterol, triglycerides, glucose or BMI were not significant. Quality of evidence was low to very low for most of outcomes.
CONCLUSIONS: LSSS significantly decreased SBP and DBP. There was no effect for detected hypertension, overall mortality and intermediate outcomes. Large, long-term RCTs are necessary to clarify salt substitute effects on clinical outcomes.
Although the evidence is not convincing enough to endorse public policy strategies, as a practising clinician, I think this paper supports an individual advice for healthy people or subjects with borderlined hypertension.
This is an important analysis with focus on the evidence of low-sodium salt substitutes on clinical outcomes. The study highlights the low quality of studies within this field and the need for more rigorous studies to gain further evidence that might impact public Health.
This SR investigating the effect of low sodium substitute on blood pressure, which concluded that low sodium substitute can reduce BP by 8/4 mmHg in average. The quality of evidence was not very high. This paper is useful but more studies are required for this issue!