Pyschophysiology, 39, S65
The goal of this study was to assess the relationship between long-term increases in hydration status and resting blood pressure. Total body water (TBW), intracellular body water (ICW), extracellular body water (ECW), and percentage of total body water by weight (TBW%) were assessed via electrical bio-impedance (MultiScan 5000, BodyStat, Ltd) in 40 undergraduate students during two laboratory sessions:
An initial hydration assessment session (Session 1) and during a follow-up session 3 days later (Session 2). Following the initial body water assessment, all participants were given six 1-liter bottles of commercially available water and instructed to consume two bottles (2 liters) of water per day in addition to their normal daily fluid intake.
During the follow-up session, body water was again assessed as well as resting blood pressure (SBP, DBP) via an automated blood pressure monitor (Colin Medical, Inc). Change scores were computed (Session 2 - Session 1) for each of the body water measures.
Pearson correlational analyses revealed significant inverse relationships between Session 2 resting SBP and changes in ECW (r = -0.31, p<.05), ICW (r = -0.40, p<.05), TBW (r = -0.39, p<.05), and TBW% (r = -0.49, p<.01). Changes in body water were not significantly related to DBP at Session 2, although change in TBW% was marginally significantly related to DBP (r = -0.30, p=.06) and all other correlations were in the same direction as those for SBP. The results of this study therefore suggest that long-term hydration enhancement may facilitate a reduction in resting blood pressure.