title: Impact of Isotonic Beverage on the Hydration Status of Healthy Chinese Adults in Air-Conditioned Environment.
abstract: People living in tropical climates spend much of their time in confined air-conditioned spaces, performing normal daily activities. This study investigated the effect of distilled water (W) or isotonic beverage (IB) on the hydration status in subjects living under these conditions. In a randomized crossover design, forty-nine healthy male subjects either consumed beverage or IB over a period of 8 h (8 h) in a controlled air-conditioned environment. Blood, urine, and saliva samples were collected at baseline and after 8 h. Hydration status was assessed by body mass, urine output, blood and plasma volume, fluid retention, osmolality, electrolyte concentration and salivary flow rate. In the IB group, urine output (1862 ± 86 mL vs. 2104 ± 98 mL) was significantly lower and more fluids were retained (17% ± 3% vs. 7% ± 3%) as compared to W (p< 0.05) after 8 h. IB also resulted in body mass gain (0.14 ± 0.06 kg), while W led to body mass loss (-0.04 ± 0.05 kg) (p= 0.01). A significantly smaller drop in blood volume and lower free water clearance was observed in IB (-1.18% ± 0.43%; 0.55 ± 0.26 mL/min) compared to W (-2.11% ± 0.41%; 1.35 ± 0.24 mL/min) (p< 0.05). IB increased salivary flow rate (0.54 ± 0.05 g/min 0.62 ± 0.04 g/min). In indoor environments, performing routine activities and even without excessive sweating, isotonic beverages may be more effective at retaining fluids and maintaining hydration status by up to 10% compared to distilled water.
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, 14 Medical Drive #07-02, MD 6 Building, Yong Loo Lin School of Medicine, Singapore 117599, Singapore. siow_phei_ching@sics.a-star.edu.sg.
authors.forename: Phei Ching
authors.initials: PC
authors.lastname: Siow
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, 14 Medical Drive #07-02, MD 6 Building, Yong Loo Lin School of Medicine, Singapore 117599, Singapore. Kimberly_tan@sics.a-star.edu.sg.
authors.forename: Wei Shuan Kimberly
authors.initials: WS
authors.lastname: Tan
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, 14 Medical Drive #07-02, MD 6 Building, Yong Loo Lin School of Medicine, Singapore 117599, Singapore. jeya_henry@sics.a-star.edu.sg.|Department of Biochemistry, National University of Singapore, 8 Medical Drive, Singapore 117596, Singapore. jeya_henry@sics.a-star.edu.sg.
authors.forename: Christiani Jeyakumar
authors.initials: CJ
authors.lastname: Henry
mesh_terms: D000328:Adult; D044466:Asian People; D001628:Beverages; D015415:Biomarkers / Q000097:blood / Q000652:urine; D015992:Body Mass Index; D018592:Cross-Over Studies; D003681:Dehydration / Q000097:blood / Q000517:prevention & control* / Q000652:urine; D060766:Drinking Water / Q000008:administration & dosage; D004573:Electrolytes / Q000097:blood / Q000652:urine; D015444:Exercise; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D012463:Saliva / Q000737:chemistry; D014882:Water-Electrolyte Balance; D055815:Young Adult
chemical_list: D015415:Biomarkers; D060766:Drinking Water; D004573:Electrolytes
keywords: air-conditioning; fluid retention; hydration; indoor; isotonic beverage