Food Quality and Design Group, Wageningen University, Wageningen, Netherlands.
Curr Pharm Des. 2017;23(19):2876-2905. doi: 10.2174/1381612823666170105151800.
Green tea is traditionally known to induce mental clarity, cognitive function, physical activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance. These effects were observed when these phytochemicals were consumed separately and in combination.
A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance.
Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.
传统上，绿茶被认为能提神醒脑、增强认知功能、促进身体活力和放松身心。最近，一种特殊的绿茶——抹茶，在全球范围内迅速流行起来，常被称为一种调节情绪和大脑的食物。与普通绿茶相比，抹茶的饮用能摄入更多的绿茶植物化学物质。先前关于茶成分咖啡因、茶氨酸和表没食子儿茶素没食子酸酯（EGCG）的研究反复证明了它们对情绪和认知表现的益处。当这些植物化学物质单独或组合摄入时，都观察到了这些效果。
对 49 项人类干预研究进行了综述，以总结咖啡因、茶氨酸和 EGCG 对不同维度的情绪和认知表现的急性精神活性影响的研究。
咖啡因主要提高对长时间高要求认知任务和自我报告的警觉性、觉醒度和活力的表现。40 毫克的低剂量就会产生显著效果。单独的茶氨酸在 200 毫克时开始改善自我报告的放松、紧张和平静。茶氨酸和咖啡因的组合被发现特别能改善注意力转换任务和警觉性的表现，但不如单独使用咖啡因的效果明显。由于干预研究的数量有限，因此无法给出与 EGCG 诱导的效果有关的明确结论。这些研究提供了可靠的证据，表明茶氨酸和咖啡因对维持注意力、记忆力和抑制分心有明显的有益作用。此外，茶氨酸通过降低咖啡因引起的觉醒度来产生放松效果。
