Why Booch?

I have a coworker that redresses me every time I come back from the vending machine, saying things like “Aspartame is cancer causing”, or “That’s just preservatives”, or even, “Pop Tarts are not actually food” (Despite the fact that, according to the package, they are a, ‘…Good Source of 6 Vitamins & Minerals'”.
 
My questions follow: 
1.) Is Kombucha a good source of Aspertame and/or Caffeine?
2.) Where should I get any other vitamins/minerals *not* found in Pop-Tarts?
3.) Is colon flora pseudo-science?
 
Thanks!