Of course, freshly brewed tea is more fragrant, tasty, contains useful substances. The toning properties of tea are shown in freshly brewed drink. Tea which is made in advance loses taste and aroma. Essential oils which are responsible for gustatory qualities long don't remain.
With confidence it is possible to tell that tea which long stood definitely doesn't gain useful properties. Most likely, on the contrary, loses. If tea leaves stayed more than twenty hours, then it will become suitable nutrient medium for bacteria and fungi. About advantage in that case there is no speech.
Chinese compare tea which long stayed made to poison. Tea loses useful properties, vitamins which in it contain, collapse.
The fact that tea will lose useful qualities, not so terribly. And here if as a result of interaction with oxygen organic matter which contains in tea is oxidized, then harm can be done to an organism. The thin film which appeared on a drink surface can tell us about oxidation process. It is better not to have such tea!
This film contains a difficult chemical formula. As it not soluble, getting to an organism, a film envelops an intestinal wall and a stomach. It it interferes with absorption through a mucous membrane of an intestinal path of nutritive matters. Also the intestines vermicular movement is broken. And in digestive tract food masses collects.
Harm can be done also to a liver. For the reason that the same film will cover a liver, it won't be able to perform the cleaning functions for all hundred percent.