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

Summary 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, I 2  = 77.3%, P  = .16). Total water intake was not associated with all‐cause mortality (ES: 0.94; 95% CI: 0.82‐1.08, I 2  = 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, I 2  = 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.