Aside from retaining caffeine, is there any bad side effect to consuming lots of coffee while on?

Coffee good! Sorry, i was trying to do a neanderthal imitation. 3 observational studies were recently published extolling the benefits of coffee & caffeine consumption although they don't prove cause & effect, just correlation. More importantly, you don't necessarily retain caffeine per se but w/excess intake, you might notice palpitations, tremors & increase urination (diuretic effect).