The caffeine (theine) in green tea isn't in its pure form, it's bound with tannin. Therefore, the effect on the nervous and cardiovascular systems is much more gentle compared to the effect of coffee. In addition to caffeine, green tea contains theobromine, which has an stimulating effect, and theophylline, which helps oxygenate blood. Green tea contains a large amount of vitamins C, A (carotene), E, P, group B, catechins, flavonoids, valuable amino acids and enzymes. It also contains micro elements and minerals: calcium, potassium, sodium, fluorine, magnesium, iron, iodine, phosphorus, gold.