Drinking water salinity and risk of hypertension: A systematic review and meta-analysis

We summarized epidemiological studies assessing sodium in drinking water and changes in blood pressure or hypertension published in English from 1960 to 2015 from PubMed, Scopus, and Web of Science. We extracted data on blood pressure level or prevalence of hypertension and calculated pooled estimates using an inverse variance weighted random-effects model. The pooled standardized mean difference (SMD) in 7 studies (12 data sets) comparing the low and high water sodium exposure groups for systolic blood pressure (SBP) was 0.08 (95% CI, -0.17 to 0.34) and for diastolic blood pressure (DBP) was 0.23 (95% CI, 0.09-0.36). Of the 3 studies that assessed the association between high water sodium and odds of hypertension, 2 recent studies showed consistent findings of higher risk of hypertension. Our systematic review suggests an association between water sodium and human blood pressure (more consistently for DBP) but remain inconclusive because of the small number of studies (largely in young populations) and the cross-sectional design and methodological drawbacks. In the context of climate-change-related sea level rise and increasing saltwater intrusion into drinking water sources, further research is urgently warranted to investigate and guide intervention in this increasingly widespread problem.