茶中含有咖啡碱、茶碱和可可碱。这些生物碱有振奋精神、曾强心肌收缩力，改善血液循环的功效。

Tea contains theine, theophylline and   pentoxifylline. Those alkaloids have the efficacy of elevating spirit, strengthening myocardial contractility and improving blood circulation.