Peter,

> Also, I have often wondered that if antibiotics kill off the good flora in
> our intestines, why is it that most people after a treatment of antibiotics
> are able to digest their foods with no problem?

I don't think the intestinal flora are just for digestion.  They produce
a number of useful things, and those byproducts are useful to our immune
system.  Without them our immune system is, presumably, weaker.