Grean tea is a fantastic immune-boosting food, and the only caffeinated beverage whose benefits far outweigh the bad points. Amongst other things it contains anti-cancer compounds. Black tea has some of the benefits of green tea, but twice the cafeine. Coffee has even more cafiene and virtually no health benefits.
Believe it or not Decaffinated coffee (and tea I suppose) is made using paint-stripper and/or dry-cleaning fluid. These harsh detergents are used to literally strip the cafeine away. The problem is that not all the detergent gets washed in the removal process, so by necessity some will remain.
So next time you have a decaff - rememember you're not just drinking coffee - you've also got some paint-stipper / dry-cleaning fluid for free!
Caffeine is not the best thing for either the liver or candida, but some will not hurt, especially if it is in the form of green tea. Dr Sandra Cabot's liver boosting supplement (livatone plus) contains green tea extract amongst other things.