Markers of the hydration process during fluid volume modification in women with habitual high or low daily fluid intakes

Abstract

Urinary markers and TPP are sensitive measures to habitual high and low TWI and to changes in TWI. Both groups through urinary and some hematological responses following TWI manipulation achieved regulation of hemoconcentration.

Distinguishing Low and High Water Consumers—A Paradigm of Disease Risk

“…Details of the experimental designs (study 1 and study 2) appear in Table 1. The slopes (i.e., gain) of the arrows for UOSM and UVOL are similar in both published studies [20,21], suggesting that the relationship between TWI and UOSM in panel A, as well as that between 24-h TWI and UVOL in panel B (i.e., both of which represent fluid-electrolyte regulation), were similarly sensitive regardless of the initial habitual fluid intake (LOW or HIGH) or whether TWI increased or decreased during experimental interventions.…”

“…Between-group comparisons also indicate no statistical differences (p > 0.05) of extracellular osmolality (P OSM and S OSM ) and serum sodium (S Na+ ), although the mean LOW values consistently tend to be greater than those of HIGH. In classical terms, these findings suggest that both LOW and HIGH live in a state of euhydration (e.g., within the set point zone in Figure 1; [2,11,21]), even though their 24-h water intakes differ by Table 1). In contrast to these non-significant findings, urine biomarkers (U VOL , U OSM , U SG ) indicate statistically significant between-group differences (range, p < 0.05 to 0.001), with LOW exhibiting a smaller 24-h urine volume and a more concentrated urine (versus HIGH).…”

“…Subsequently, while investigating the possibility that a low TWI is associated with an increased risk of degenerative diseases or diminished physiological function, investigators began to compare numerous water-relevant variables of LOW to those of habitual high volume drinkers (HIGH), including perceptual ratings (e.g., thirst sensation using a visual analog scale or category numerical ratings) and plasma AVP concentrations. In these observational studies [9,18,20,21], the 24-h TWI of LOW ranged from 0.7-1.6 L•d −1 and HIGH ranged from 2.5-3.3 L•d −1 . Urinary variables (e.g., urine specific gravity (U SG ), osmolality (U OSM ), color (U COL ) and volume (U VOL )) distinguished LOW from HIGH, in that LOW excreted a smaller volume of concentrated urine because they consumed less water each day [9,18].…”

“…Three investigations have intervened in the water homeostasis of LOW and HIGH by reversing their habitual 24-h water intakes. Table 2 presents the findings of these investigations [18,20,21] in the form of physiological changes from baseline that occurred across 3-4 d when LOW consumed 1.5-1.9 L•d −1 more than usual and when HIGH decreased their usual intake by 1.2-1.6 L•d −1 . As anticipated, P AVP decreased and U VOL increased in the modified LOW group, whereas these responses changed in the opposite directions in the modified HIGH group.…”

Beverage Intake Assessment Questionnaire: Relative Validity and Repeatability in a Spanish Population with Metabolic Syndrome from the PREDIMED-PLUS Study

“…The associations between hydration, water, or beverage intake with health or disease has recently become an important area of research [1,2]. Several authors have assessed the relationship between the consumption of beverages and specific outcomes: for example, the intake of sugar-sweetened beverages (SSBs) and metabolic syndrome (MetS) or type 2 diabetes (T2DM) [3], hypertension [4,5,6] and other cardiometabolic variables [7]; or the intake of drinking water and its relationship to cardiovascular diseases (CVD) [8].…”