Urinary Caffeine After Coffee Consumption and Heat Dehydration

This study evaluated the effect of heat-induced dehydration on urinary caffeine excretion after the consumption of a strong coffee solution. Following ingestion of coffee (caffeine 4.9 ± 0.1 [SE] mg/kg, 3 - 4 cups), ten healthy males were intermittently exposed to heat in a sauna until they had lost...

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Bibliographic Details
Published in:International journal of sports medicine 2001-07, Vol.22 (5), p.366-372
Main Authors: Chambaz, A., Meirim, I., Décombaz, J.
Format: Article
Language:English
Subjects:
Adult
Biological and medical sciences
Caffeine - administration & dosage
Caffeine - metabolism
Caffeine - urine
Case-Control Studies
Chromatography, High Pressure Liquid
Coffee
Dehydration - physiopathology
Hot Temperature
Humans
Male
Medical sciences
Neuropharmacology
Nutrition
Pharmacology. Drug treatments
Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease)
Psychology. Psychoanalysis. Psychiatry
Psychopharmacology
Saliva - chemistry
Statistics, Nonparametric
Steam Bath
Sweat - chemistry
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Summary:This study evaluated the effect of heat-induced dehydration on urinary caffeine excretion after the consumption of a strong coffee solution. Following ingestion of coffee (caffeine 4.9 ± 0.1 [SE] mg/kg, 3 - 4 cups), ten healthy males were intermittently exposed to heat in a sauna until they had lost 2.9 % of lean mass. On a separate occasion, they consumed the same amount of coffee but remained quiet and euhydrated (control). Urine flow was reduced 7-fold in dehydration. At these low excretion rates (< 30 ml/h), caffeine concentration was negatively correlated with flow. Peak urinary caffeine (C max ) was 7.6 ± 0.4 (SE) μg/ml in dehydration and 7.1 ± 0.2 μg/ml in the control (p > 0.05). Compared with the control, dehydration delayed C max by 1 hour, maintained higher saliva caffeine concentration (6.1 vs 5.2 μg/ml, p < 0.05) and a lower saliva paraxanthine/caffeine ratio (p < 0.001). The 24h-recovery of caffeine in urine was reduced (1.2 vs 2.8 % of dose, p < 0.001), however at least 2.6 % of dose were lost in sweat. These results suggest that the rise in circulating caffeine due to delayed metabolic clearance was partly opposed by a sizeable elimination in sweat. Therefore, heat dehydration did not lead to higher concentration of caffeine in urine after coffee ingestion.
ISSN:0172-4622
1439-3964
DOI:10.1055/s-2001-15646