Abstract
Objectives
To assess the acute effect of adequate water consumption on copeptin, a marker of arginine vasopressin, in low drinkers.
Methods
Six healthy (5 males, 1 female) low drinkers (age 43 ± 7 y, BMI 30.5 ± 3) were recruited based on self-reported daily water consumption ≤1.5 L·day−1 in males or 1.0 L·day−1 in females (854 ± 432 mL·d−1) and 24-h urine osmolality ≥800 mmol·kg−1 (968 ± 114 mmol·kg−1). Participants completed two counterbalanced crossover 11-h protocols. They were provided either the Institute of Medicine's recommended amount of water excluding food (males: 3 L, females: 2 L, HWI) or an amount representing the bottom quartile of water consumption observed in the National Health and Nutrition Examination Survey (males: 0.5 L, females: 0.4 L, LWI). Food was provided to participants and standardized to body weight (100 kJ·Kg−1) using a consistent ratio of macronutrients. Blood samples were collected at hours 700, 800, 900, 1200, 1300, 1400, 1600, 1700, and 1800.
Results
There was a significant main effect of water intake on plasma osmolality (F = 11.838, P = 0.018) with greater values in LWI at 1200 (HWI: 287 ± 3, LWI: 291 ± 3; P = 0.013), 1400 (HWI: 287 ± 4, LWI: 291 ± 5; P = 0.049), and 1700 (HWI: 287 ± 2, LWI: 292 ± 4; P = 0.004). There was also a significant main effect of water intake on copeptin (F = 9.848, P = 0.026) with higher values in LWI at 0800 (HWI: 6.1 ± 2.3, LWI: 8.7 ± 3.7; P = 0.016), 0900 (HWI: 5.3 ± 2.4, LWI: 9.2 ± 4.5; P = 0.013), 1200 (HWI: 4.2 ± 1.9, LWI: 7.8 ± 4.6; P = 0.021), 1400 (HWI: 4.3 ± 1.8, LWI: 8.3 ± 4.7; P = 0.033), 1600 (HWI: 4.7 ± 2.5, LWI: 7.6 ± 4.5; P = 0.049), and 1800 (HWI: 4.4 ± 2.5, LWI: 7.8 ± 5.2; P = 0.048). Water intake did not influence change in plasma volume (P = 0.214).
Conclusions
Copeptin was suppressed in response to acute increases in water consumption via suppression of plasma osmolality. Copeptin may serve as a sensitive marker for changes in total water intake.
Funding Sources
This study was supported by Arizona State University College of Health Solutions.
Effect of water temperature in drinkers and their location on water intake by cows
