Here is a pretty good link discussing both solulble and insoluble fibre.....
http://www.healthyeatingstartshere.com/nutrition/soluble-fiber-vs-insoluble-fiber
There is a fine line and as a crohnie you do have to walk it but fibre is a very necessary aid to our digestive tract and overall health as well.
I just wanted to note as well, I found since I stopped eating/drinking processed foods, I no longer have bad breath issues, although I'm an avid flosser daily, still I find that my breath is no longer foul and although I'm an advocate for giving up all processed foods/beverages, I know that for many, diet is individual for IBDers...just wanted to clarify that in diet/food discussions I'm never pointing my finger at anyone based on the fact that I've cut out all processed foods and only eat natural foods, I only try to encourage people to eat as healthy as possible, at the same time I do realise that not everyone can tolerate all natural foods and by only eating the natural foods they can tolerate I know it limits their choices.