Community and Public Health Nutrition
Objectives : In 2005, US water intake recommendations were based on analyses of NHANES III data that examined if hydration classification varied by water intake and estimated the median water intake associated with hydration in persons ages 19-30y. Given the upcoming 2020-2025 Dietary Guidelines review, this analysis addressed the same two aims with 2009-2012 NHANES data.
Methods : Methods were updated by defining hydration criteria in terms of multiple measures (serum sodium 135-144 mmol/l and urine osmolality< 500 mmol/kg), expressing water intake as ml/kg, distinguishing plain water intake (PWI) from total water intake (TWI), using weighted age- and sex-specific multivariable models to control for determinants of water intake requirements, and selecting two study samples (non-acutely ill U.S. population and a sub-group without selected chronic disease risk factors).
In the U.S. population and sub-group, TWI ≥45 ml/kg or PWI ≥20 ml/kg was associated with about two times greater relative odds of meeting the hydration criteria (Overall for U.S. men 12-80y: Adj. OR=1.90, 95%CI: 1.56-2.32; Overall for U.S. women 12-80y: Adj. OR=1.97, 95%CI: 1.69-2.28). In the U.S. population, among those age 19-50y who met the hydration criteria, the median (SE) TWI and PWI was 42 (2) ml/kg and 14 (1) ml/kg, respectively, for men, and 43 (2) ml/kg and 16 (1) ml/kg, respectively, for women. In the subgroup without selected chronic disease risk factors, men and women age 51-70y who met the hydration criteria had median (SE) TWI and PWI of 47 (4) ml/kg and 20 (4) ml/kg, and 46 (5) ml/kg and 23 (6) ml/kg, respectively.
Conclusions : The results suggest that the likelihood of meeting hydration criteria varies significantly by TWI and PWI and that cutoffs of 45 ml/kg TWI and 20 ml/kg PWI, corresponding to 3.9 L/d TWI and 1.7 L/d PWI for men and 3.3 L/d TWI and 1.5 L/d PWI for women, may discriminate likelihood.
Funding Sources : This research received no external funding.