guarana has as high caffeine content. :( Nope nope nope. At least the green tea is good for SOMEthing. :)
Caffeine is bad because it tells the adrenals to release adrenaline. That's the "high" of it. The adrenaline causes all kinds of weird fight-or-flight responses, same as stress, which include changes to blood pressure, insulin response, etc. Leads to adrenal exhaustion, pancreatitis, etc.
Caffiene can also mirror RDA, part of the DNA synthesis, so it can get into cells as they replicate and turn them into cancerous cells.
Caffeine throws off our biorhythms and circadian rhythms. that makes it impossible to have rejuvenating sleep, where we do most of our healing.