Total and drinking water intake and risk of all-cause and cardiovascular mortality: A systematic review and dose-response meta-analysis of prospective cohort studies

Background: Understanding the association between water consumption and mortality is important for guiding consumers and prioritizing dietary guidelines to reduce the risk. Therefore, in the current study, we conducted a systematic review and dose-response meta-analysis of prospective cohort studies to summarise the association between total water and drinking intake and risk of mortality from all causes and CVD.

Method: A comprehensive search was performed on PubMed/Medline, Scopus, and ISI Web of Science up to February 2020. The random-effects model was used to calculate the pooled effect size (ES) and 95% confidence interval.

Result: Seven prospective cohort studies were included in the systematic review and meta-analysis. During the follow-up period of 6 to 19.1 years, 14 754 deaths (7611 from cardiovascular disease) occurred among 116 816 participants. No significant association was found between drinking water intake and all-cause mortality (ES: 0.82; 95% CI: 0.63-1.08, I² = 77.3%, P = .16). Total water intake was not associated with all-cause mortality (ES: 0.94; 95% CI: 0.82-1.08, I² = 66.5%, P = .41). However, a significant inverse association was seen between total water intake and risk of CVD mortality (ES: 0.86; 95% CI: 0.78-0.95, I² = 0%, P = .002). Linear dose-response meta-analysis revealed a significant inverse association between total water intake and all-cause mortality by an additional one cup per day (pooled ES: 0.98; 95% CI: 0.97-0.99, P = .001). Furthermore, each additional cup of total water intake per day was associated with a 3% lower risk of death from CVD (pooled ES: 0.97; 95% CI: 0.96-0.98, P < .001).

Conclusion: High consumption of total water is associated with a lower risk of CVD mortality. However, total water intake was not associated with risk of all-cause mortality.