A prospective study of water intake and subsequent risk of all-cause mortality in a national cohort

Background: Water, an essential nutrient, is believed to be related to a variety of health outcomes. Published studies have examined the association of fluid or beverage intake with risk of mortality from coronary diseases, diabetes, or cancer, but few studies have examined the association of total water intake with all-cause mortality. Objective: We examined prospective risk of mortality from all causes in relation to intakes of total water and each of the 3 water sources. Design: We used public-domain, mortality-linked water intake data from the NHANES conducted in 1988-1994 and 1999-2004 for this prospective cohort study (n = 12,660 women and 12,050 men; aged >= 25 y). Mortality follow-up was completed through 31 December 2011. We used sex-specific Cox proportional hazards regression methods that were appropriate for complex surveys to examine the independent associations of plain water, beverage water, water in foods, and total water with multiple covariate adjusted risk of mortality from all causes. Results: Over a median of 11.4 y of follow-up, 3504 men and 3032 women died of any cause in this cohort. In men, neither total water intake nor each of the individual water source variables (plain water, water in beverages, and water in foods) was independently related with risk of all-cause mortality. In women, risk of mortality increased slightly in the highest quartile of total or plain water intake but did not approach the Bonferroni-corrected level of significance of P < 0.002. Conclusions: There was no survival advantage in association with higher total or plain water intake in men or women in this national cohort. The slight increase in risk of mortality noted in women with higher total and plain water intakes may be spurious and requires further investigation.