Urinary caffeine after coffee consumption and heat dehydration
Urinary caffeine after coffee consumption and heat dehydration
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DOI：
10.1055/s-2001-15646
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发表时间：
2001-07-01
影响因子：
2.5
通讯作者：
Décombaz, J
中科院分区：
文献类型：
--
作者：
Chambaz, A;Meirim, I;Décombaz, J
这项研究评估了热诱导脱水对饮用浓咖啡溶液后尿咖啡因排泄的影响。在摄入咖啡（咖啡因4.9 +/- 0.1 [SE] mg/kg，3 - 4杯）后，10名健康男性间歇性地暴露于桑拿中的热量，直到他们失去2.9%的瘦体重。在另一种情况下，他们喝同样量的咖啡，但保持安静和水分充足（对照）。脱水时尿流减少7倍。在这些低排泄率（< 30 ml/h）下，咖啡因浓度与流量呈负相关。脱水组尿咖啡因峰值（C-max）为7.6 ± 0.4（SE）μ g/ml，对照组为7.1 ± 0.2 μ g/ml（p > 0.05）。与对照组相比，脱水使C-max延迟1小时，保持较高的唾液咖啡因浓度（6.1 vs 5.2 μ g/ml，p < 0.05）和较低的唾液副黄嘌呤/咖啡因比率（p < 0.001）。尿液中咖啡因的24小时回收率降低（1.2% vs 2.8%剂量，p < 0.001），但汗液中至少损失了2.6%的剂量。这些结果表明，由于代谢清除延迟而导致的循环咖啡因的增加部分地被汗液中相当大的消除所抵消。因此，热脱水不会导致摄入咖啡后尿液中咖啡因浓度升高。
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) mug/ml in dehydration and 7.1 +/- 0.2 mug/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 mug/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.