i think that while the intestine is ulcerated veggies and nuts are a problem, but when in remission they should be fine.
people will offer all sorts of advice about food so here's mine, make what you will of it.
Problem foods fall into three groups,
we're all aware of one group, many aware of two but most people don't want to know about the third group.
firstly, The painful ones,
imagine nuts of carrots or whatever rough food sliding through an ulcerated section of intestine, scraping off the mucus and opening up the scabs
secondly, the reactive ones,
many crohnies have food allergies, often multiple allergies, -an adverse reaction to food protiens. In most cases ( i think) due to intestinal permeability, - the gut allowing proteins through the intestinal wall that normally would not be allowed into the blood.
thirdly, the underlying problem.
we evolved to eat veggies, then about 2.5 million years ago made a leap to eating meat, probably leading to the rapid increase in brain size,
(check out Loren Cordain - Origins and Evolution of the Western Diet: Health Implications for the 21st Century.
http://www.youtube.com/watch?feature=player_embedded&v=5dw1MuD9EP4#
then we added grain, and it rapidly became the staple, enabling civilisation as we know it, but many people can't digest them and one of the proven effects of grains and beans (especially wheat) is increased intestinal permeability. this allows undigested food and faeces into the bloodstream -guess what?- provoking multiple immune reactions.
wikipedia:-
"Defects in the intestinal epithelial barrier function have been observed in a number of bowel disorders such as inflammatory bowel disease (IBD). It is now becoming evident that an aberrant epithelial barrier function plays a central role in the pathophysiology of IBD, gastrointestinal diseases, cardiovascular disease, acute and chronic pediatric and other recognised diseases. Intestinal permeability is also increased in skin conditions such as psoriasis and atopic eczema"
the sad thing is that the real problem foods are considered 'safe foods' - paste, white bread, etc.
that's just my opinion, but check out the paleo thread