Well arrowslinger, I remember when I first came to this forum, it really struck me from the posts that CD came in different "flavours" - people fell into different categories of what sorts of foods would be okay, or make them ill. You find the flavour you have, tweak it (that's the hard bit) and hey presto, suddenly you have some kind of a handle on things, until the dreaded flare occurs. And of course if that is so, then taking a whole heap of people at random who don't manage their diet properly and looking to see if there is any appreciable difference in their health outcomes...well, it isn't really likely to be good science. And surprise surprise, what the studies say is contradicted by the people who know best.
I'm with yellowfin - diet doesn't cause Crohn's, in the same way that feeding tartrazine to a child with hyperactivity doesn't make it misbehave !
Me, I find that keeping to a gluten and dairy free, low salt and sugar diet makes a huge difference. Also, and I wonder how much this is a problem for other Crohnies, I find I am sensitive to some of the sprays or chemicals associated with non-organic foods; or maybe it is that they are lacking certain minerals or beneficial chemicals, like magnesium or salicylates, found in larger quantities in organic foods. That was a tough one to sort out, because it depends on what the individual growing or processing history of a food ingredient is.
For snacks I use homemade bread (gf bread is easy to make in a breadmaker) and oatcakes, often soup in a thermos when it is cold, failing that mixed grains and tomato sauce or mayo with steamed vegetables. Linseed and probiotics are two things I eat a lot more of whenever my gut plays up, they turn down the ring under the boiling pan.