I'm reading "The Fat Fallacy" right now and it's a pretty interesting read. Not much help to IBS people, but I'm needing/wanting to lose some weight, which is why I'm reading it.
However, I did read of a couple of sugar products in the book that I was not really familiar with that has been linked to G.I. problems:
"Glycerin - Irritant to G.I. mucus and problems for the metabolism and the central nervous system." Last I knew, glycerin was a product in soap. Add some to homemade bubble solution for better colors and better bubble staying power. Does it really end up in our food?
"Lactose - Diarrhea, malabsorbtion, vomiting, flatulence, jaundice and cataracts." Of course lactose naturally occurs in milk, which most people already know whether they can handle milk products or not, but apparently they're sneaking it into other foods as well--things we don't think of as containing dairy. And it may be synthetically produced when used as an additive.
Then of course there were the usual culprits: aspartame and all of the sugar alcohols.