Effect of dietary sodium restriction on arterial stiffness: systematic review and meta-analysis of the randomized controlled trials.

OBJECTIVE: Arterial stiffness is an independent cardiovascular risk factor and sodium intake could be a determinant of arterial stiffness. Nevertheless, the studies that investigated the effect of reducing dietary sodium intake on arterial stiffness in humans provided inconsistent results. Therefore, we performed a systematic review and a meta-analysis of the available randomized controlled trials of salt restriction and arterial stiffness to try and achieve more definitive conclusions.
METHODS: A systematic search of the online databases available (from 1996 through July 2017) was conducted including randomized controlled trials that reported arterial stiffness, expressed by carotid-femoral pulse wave velocity (PWV), as difference between the effects of two different sodium intake regimens. For each study, the mean difference and 95% confidence intervals were pooled using a random effect model. Sensitivity, heterogeneity, publication bias, subgroup and meta-regression analyses were performed.
RESULTS: Eleven studies met the predefined inclusion criteria and provided 14 cohorts with 431 participants and 1-6 weeks intervention time. In the pooled analysis, an average reduction in sodium intake of 89.3 mmol/day was associated with a 2.84% (95% CI: 0.51-5.08) reduction in PWV. There was no significant heterogeneity among studies and no evidence of publication bias was detected. No single feature of the studies analyzed seemed to impact on the effect of salt restriction on PWV.
CONCLUSION: The results of this meta-analysis indicate that restriction of dietary sodium intake reduces arterial stiffness. This effect seems be at least in part independent of the changes in blood pressure.