Analysis of 2009⁻2012 Nutrition Health and Examination Survey (NHANES) Data to Estimate the Median Water Intake Associated with Meeting Hydration Criteria for Individuals Aged 12⁻80 in the US Population

Abstract

In 2005, US water intake recommendations were based on analyses of Nutrition Healthand Examination Surveys (NHANES) III data that examined if hydration classification varied bywater intake and estimated the median water intake associated with hydration in persons aged 19⁻30. Given the upcoming 2020⁻2025 Dietary Guidelines review, this analysis addresses the same twoaims with the 2009⁻2012 NHANES data. Methods were updated by defining hydration criteria interms 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 ofwater intake requirements, and selecting two study samples (non-acutely ill US population and asub-group without selected chronic disease risk factors). In the US population and sub-group, therelative risk (RR) of meeting the hydration criteria was significantly greater for individuals withTWI ≥ 45 mL/kg or PWI ≥ 20 mL/kg (for the US population 19⁻50 years of age: adjusted RR (RRrepresents Relative Risk, which is a very standard term that probably does not need to be spelledout) = 1.36, 95% CI: 1.10⁻1.68 for males; adjusted RR = 1.70, 95% CI: 1.49⁻1.95 for females. For thesub-group 51⁻70 years of age: adjusted RR = 2.20, 95% CI: 1.15⁻4.18 for males; adjusted RR = 2.00,95% CI: 1.18⁻3.40 for females). The median (SE, which stands for Standard Error, which is also verywell known. Up to you if your journal prefers to spell it out in the abstract) TWI and PWI associatedwith meeting the hydration criteria for males and females 19⁻50 years of age were 42 (2) mL/kg and14 (1) mL/kg and 43 (2) mL/kg and 16 (1) mL/kg, respectively. The significant association betweenwater intake and hydration classification differs from the null association, underlying the 2005 waterintake recommendations, and may lead to different reasoning and inferences for the 2020⁻2025Dietary Guidelines.

Keywords: drinking water; hydration; serum sodium; total water intake; urine osmolality.

Figure 1

Serum sodium and urine osmolality of males and females in the US population. Each dot represents the serum sodium and urine osmolality of one NHANES 2009–2012 participant. Blue dots represent participants that had both a serum sodium values between 135–144 mmol/L and a urine osmolality below 500 mmol/kg.

Figure 2

Total water intake (TWI) and plain water intake (PWI) of males and females in the study population. The figure illustrates the correlation between total water intake and plain water intake. Each dot represents the TWI and PWI of one NHANES 2009–2012 participant.

Figure 3

Predicted probability of meeting hydration criteria associated with TWI at or above cutoffs ranging from 20–60 mL/kg or PWI at or above cutoffs ranging from 0–50 mL/kg for the US population and sub-group without selected chronic disease risk factors by sex and age. Participants were classified as hydrated if they had a serum sodium of 135–144 mmol/L, a urine volume ≥ 50 mL, and a urine osmolality < 500 mmol/kg. The probability of meeting the hydration criteria was predicted from weighted, age- and sex-specific logistic regression models that adjusted for age in years, body weight, solute load, race–ethnicity, level of physical activity, cigarette smoking, any prescription medication used in the past month, and season of the MEC visit. The probabilities were predicted holding each covariate at its mean for each sex and age group. See the interactive Tableau dashboard for further detail (Supplementary Figure S1).

Figure 3

Predicted probability of meeting hydration criteria associated with TWI at or above cutoffs ranging from 20–60 mL/kg or PWI at or above cutoffs ranging from 0–50 mL/kg for the US population and sub-group without selected chronic disease risk factors by sex and age. Participants were classified as hydrated if they had a serum sodium of 135–144 mmol/L, a urine volume ≥ 50 mL, and a urine osmolality < 500 mmol/kg. The probability of meeting the hydration criteria was predicted from weighted, age- and sex-specific logistic regression models that adjusted for age in years, body weight, solute load, race–ethnicity, level of physical activity, cigarette smoking, any prescription medication used in the past month, and season of the MEC visit. The probabilities were predicted holding each covariate at its mean for each sex and age group. See the interactive Tableau dashboard for further detail (Supplementary Figure S1).

Figure 4

Relationship between TWI and PWI for US males and females who met the hydration criteria in 2009–2012. Each dot represents the total water intake (TWI) and plain water intake (PWI) of one NHANES 2009–2012 participant.