First...
Think of green tea as unfermented black tea. It's tea in the raw. Not rocket science.
Second... Most natural sources of stimulants or drugs have more than the "chemically derived" active ingredient. So when someone says "this is some really good ****"
", well what they are saying is that it has a nice balance and concentration of the active ingredient(s) and similar chemical analogues. Unless an herb says "standardized extract", well then the active ingredient and constellation of similar chemicals in it can vary from batch to batch.
Next...
The main stimulant in tea is indeed caffeine. But caffeine is one of several alkaloids in tea that give it the stimulant effect. And the mix gives it the special buzz.
One such alkaloid is theobromine . Once upon a time, theophilline was a manufactured drug used for asthma. However it no longer is, because the stimulant effect goes beyond opening up the respiratory passages. Too much theophilline can give you jitters.
Green tea contains approximately 20 mg caffeine per cup. That's about a fourth to a sixth the amount of an average cup of coffee. But tea's mix of alkaloids is different from the alkaloids you find in java.
The main health reasons to drink green tea are to get the beneficial polyphenols, flavenoids, and trace minerals. EGCG in particular is a much-studied polyphenol that may be the biggest contributor to tea's beneficial effects.
The weight loss attributed to green tea likely comes from the thermogenic properties of the alkaloids and the catechin polyphenols. Some studies have shown that green tea may limit fat absorption in the GI tract by inhibiting certain digestive enzymes.
Hope that's a good start.
- Bill
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