Optimal Hydration Biomarkers: Consideration of Daily Activities

Water intake and hydration status have recently gained attention as one of the many, and potentially manipulable, factors associated with disease development and wellbeing [1–7] . Researchers have explored a variety of physiological dysfunctions implicated with chronic low water intake and hypohydration, but particular interest resides in the study of obesity and related disease states due to overwhelming prevalence. However, the current lack of a hydration assessment gold standard greatly impedes our attempts to link water intake and negative health outcomes as well as to make public dietary guidelines. Current hydration biomarkers include blood, saliva, and urine sampling subjected to a variety of quantification methods (osmolality, specific gravity, volume, etc.). Recent work from our laboratory [8] contributed to the ongoing quest to identify optimal selection of hydration biomarkers, but through consideration of the context under which body water loss occurs. We present two scenarios when selecting optimal hydration biomarkers: i) active versus passive body water loss, and ii) single versus serial measurements.