Shifting Focus: From Hydration for Performance to Hydration for Health

Abstract

Over the past 10 years, literature on hydration biomarkers has evolved considerably - from (de)hydration assessment towards a more global definition of biomarkers of hydration in daily life. This shift in thinking about hydration markers was largely driven by investigating the differences that existed between otherwise healthy individuals whose habitual, ad-libitum drinking habits differ, and by identifying physiological changes in low-volume drinkers who subsequently increase their water intake. Aside from obvious differences in urinary volume and concentration, a growing body of evidence is emerging that links differences in fluid intake with small, but biologically significant, differences in vasopressin (copeptin), glomerular filtration rate, and markers of metabolic dysfunction or disease. Taken together, these pieces of the puzzle begin to form a picture of how much water intake should be considered adequate for health, and represent a shifting focus from hydration for performance, toward hydration for health outcomes. This narrative review outlines the key areas of research in which the global hydration process - including water intake, urinary hydration markers, and vasopressin - has been associated with health outcomes, focusing on kidney and metabolic endpoints. It will also provide a commentary on how various hydration biomarkers may be used in hydration for health assessment. Finally, if adequate water intake can play a role in maintaining health, how might we tell if we are drinking enough? Urine output is easily measured, and can take into account differences in daily physical activity, climate, dietary solute load, and other factors that influence daily water needs. Today, targets have been proposed for urine osmolality, specific gravity, and color that may be used by researchers, clinicians, and individuals as simple indicators of optimal hydration. However, there remain a large number of incomplete or unanswered research questions regarding the relationships between water intake, hydration, vasopressin, and health outcomes. Thus, this emerging field represents an excellent opportunity, particularly for young researchers, to develop relevant and novel lines of research.

Racial and Sex Differences in 24 Hour Urinary Hydration Markers among Male and Female Emerging Adults: A Pilot Study

“…Increased consumption of water has been associated with a reduced risk of obesity, urinary tract infections, chronic kidney disease, cardiovascular disease, and a reduction in the incidence of hyperglycemia [5][6][7][8][9][10][11]. Despite these benefits, recent cross-sectional surveys have shown that 60% of men and 40% of women do not comply with the EFSA recommendations for daily water intake [12], which may alter the long-term health risk profile in persons who habitually consume low volumes of water on a daily basis [13,14]. Although 40% of women were found to not meet current EFSA standards, they were more than twice as likely to meet the adequate intake standards for daily fluid intake than that of men [12].…”

Impact of Nuun Electrolyte Tablets on Fluid Balance in Active Men and Women

“…Maintaining adequate hydration is essential to optimal health [ 1 , 2 , 3 ] and athletic performance [ 4 , 5 ]. Dehydration can contribute to a host of issues, including altered cognition and digestion, as well as organ dysfunction in the heart, kidneys, and skin [ 3 ].…”

What is Needed for Evidence‐Based Dietary Recommendations for Migraine: A Call to Action for Nutrition and Microbiome Research

“…Thus, practical and accurate individualized recommendations for water consumption levels remain enigmatic. Instead, monitoring of urine color according to a standardized color scale has been demonstrated to detect an elevated urine osmolality in free-living individuals, and has been suggested to be a sufficient monitoring of hydration status for the general population, 31 which may be a useful, low burden technique in individuals with migraine.…”