In most of the reports that I have read, the scientists have used the substances, such as EGCG, caffeine etc in pure extract forms to mix in water to feed the test mice or rats, such that they can prove it is that substance that is working. The dosages are small, a couple of mg for each kg of the body weight, which is one way how doctors or scientists prescribe dosage for patients.
No one can say for sure what works in the small mammals in experimental settings can work for human as yet. However, to give you an idea, for an average person who weighs say, 75 kg (ie 165 lb) to correspond with what an experiment that used, say, 3 mg/kg, the dosage for a day is 225 mg.
If that substance is EGCG, most acceptable quality green, white, or oolong whole leaf tea can easily deliver that in one or two cups, depending on the size, strength and quality of your infusion. There is no findings that over dosage of EGCG is toxic, so the more the merrier.
If the substance in consideration is caffeine, restrain your intake to 300 mg a day on the safe side. Overdosage has proven to be not contributive to neuron protection. Read more about caffeine calculation in related Tea Guardian chapters, eg:
If the substance you are interested in is theanine, a couple of hundred mg will require higher quality tealeaves and drinking 4 to 5 150 ml cups at medium strength a day, according to the strength of the Korean experiment and the content findings in the Taiwan study, both of which are referenced in the TG article.
I have to stress here again that tea is a total package that comes with a lot of substances, the three that mentioned are only what scientists have taken popular notice of, their synergic effect, and that with all the other substances in tea, and that in various proportions in different varieties of tea, has never been seriously studied. It is also interesting to note that some reports I have read but not referenced in the article, which are cohort studies and observations of cohort studies, reflects a stunning alignment with all other studies about the health effect of tea:
The positive effects are not as consistent or proven in populations in the West, but dramatically positive in populations in the East, esp in Japan, Taiwan, China and Singapore. I think besides genetics and life and diet styles, one strong reason is the prevalent poor quality of tea being drunk in the West. I hope I am not offending anyone here, but that is a description of the market condition that people like yourself, who are aware of the dramatic difference, should be saving yourselves from, if not also helping the others around you.
