Fluid, electrolyte, and renal indices of hydration during 11 days of controlled caffeine consumption.
This investigation determined if 3 levels of controlled caffeine consumption affected fluid-electrolyte balance and renal function differently. Healthy males (mean +/- standard deviation; age, 21.6 +/- 3.3 y) consumed 3 mg caffeine . kg(-1) . d(-1). on days 1 to 6 (equilibration phase). On days 7 to 11 (treatment phase), subjects consumed either 0 mg (C0; placebo; n= 20), 3 mg (C3; n = 20), or 6 mg (C6; n = 19) caffeine . kg(-1) . d(-1) in capsules, with no other dietary caffeine intake. The following variables were unaffected (P > 0.05) by different caffeine doses on days 1, 3, 6, 9, and 11 and were within normal clinical ranges: body mass, urine osmolality, urine specific gravity, urine color, 24-h urine volume, 24-h Na+ and K+ excretion, 24-h creatinine, blood urea nitrogen, serum Na+ and K+, serum osmolality, hematocrit, and total plasma protein. Therefore, C0, C3, and C6 exhibited no evidence of hypohydration. These findings question the widely accepted notion that caffeine consumption acts chronically as a diuretic.
Armstrong
Lawrence E
LE
University of Connecticut, Human Performance Laboratory, Storrs, CT 06269, USA.
Pumerantz
Amy C
AC
Roti
Melissa W
MW
Judelson
Daniel A
DA
Watson
Greig
G
Dias
Joao C
JC
Sokmen
Bulent
B
Casa
Douglas J
DJ
Maresh
Carl M
CM
Lieberman
Harris
H
Kellogg
Mark
M
D000293:Adolescent; D000328:Adult; D001834:Body Water / Q000187:drug effects* / Q000378:metabolism; D002110:Caffeine / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D003681:Dehydration / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D007677:Kidney Function Tests; D008297:Male; D014882:Water-Electrolyte Balance / Q000187:drug effects* / Q000502:physiology
D000697:Central Nervous System Stimulants; D002110:Caffeine