School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
J Nutr Biochem. 2013 Jan;24(1):325-34. doi: 10.1016/j.jnutbio.2012.06.017. Epub 2012 Sep 10.
Green tea catechins have been hypothesized to increase energy expenditure and fat oxidation by inhibiting catechol-O-methyltransferase (COMT) and thus promoting more sustained adrenergic stimulation. Metabolomics may help to clarify the mechanisms underlying their putative physiological effects.
The study investigated the effects of 7-day ingestion of green tea extract (GTE) on the plasma metabolite profile at rest and during exercise.
In a placebo-controlled, double-blind, randomized, parallel study, 27 healthy physically active males consumed either GTE (n=13, 1200 mg catechins, 240 mg caffeine/day) or placebo (n=14, PLA) drinks for 7 days. After consuming a final drink (day 8), they rested for 2 h and then completed 60 min of moderate-intensity cycling exercise (56% ± 4% VO(2)max). Blood samples were collected before and during exercise. Plasma was analyzed using untargeted four-phase metabolite profiling and targeted profiling of catecholamines.
Using the metabolomic approach, we observed that GTE did not enhance adrenergic stimulation (adrenaline and noradrenaline) during rest or exercise. At rest, GTE led to changes in metabolite concentrations related to fat metabolism (3-β-hydroxybutyrate), lipolysis (glycerol) and tricarboxylic acid cycle (TCA) cycle intermediates (citrate) when compared to PLA. GTE during exercise caused reductions in 3-β-hydroxybutyrate concentrations as well as increases in pyruvate, lactate and alanine concentrations when compared to PLA.
GTE supplementation resulted in marked metabolic differences during rest and exercise. Yet these metabolic differences were not related to the adrenergic system, which questions the in vivo relevance of the COMT inhibition mechanism of action for GTE.
儿茶素通过抑制儿茶酚-O-甲基转移酶（COMT）从而促进更持久的肾上腺素刺激，被认为可以增加能量消耗和脂肪氧化。代谢组学可能有助于阐明其潜在生理作用的机制。
本研究调查了 7 天摄入绿茶提取物（GTE）对静息和运动时血浆代谢物谱的影响。
在一项安慰剂对照、双盲、随机、平行研究中，27 名健康的有运动习惯的男性分别摄入 GTE（n=13，1200mg 儿茶素，240mg 咖啡因/天）或安慰剂（n=14，PLA）饮料，共 7 天。在饮用最后一杯饮料（第 8 天）后，他们休息 2 小时，然后完成 60 分钟的中等强度自行车运动（56%±4%VO2max）。在运动前后采集血液样本。使用非靶向四相代谢物分析和儿茶酚胺靶向分析对血浆进行分析。
使用代谢组学方法，我们发现 GTE 并没有增强静息和运动时的肾上腺素刺激（肾上腺素和去甲肾上腺素）。静息时，与 PLA 相比，GTE 导致与脂肪代谢（3-β-羟丁酸）、脂肪分解（甘油）和三羧酸循环（TCA）中间产物（柠檬酸）相关的代谢物浓度发生变化。与 PLA 相比，GTE 在运动时还导致 3-β-羟丁酸浓度降低，丙酮酸、乳酸和丙氨酸浓度升高。
GTE 补充剂在静息和运动时导致明显的代谢差异。然而，这些代谢差异与肾上腺素系统无关，这对 GTE 的儿茶酚-O-甲基转移酶抑制作用机制的体内相关性提出了质疑。
