I do not have Crohns Disease, but have sympathy for those who do.
When I was at the store recently and had two boxes of oatmeal in my cart, a young man ahead of me said that's what he eats. He said he had 2 surgeries already, and if he doesn't follow a strict "vegi" diet he knows that right away.
...............
I had part of my colon removed as there was a polyp on the valve between the upper and lower colon that could not be removed without surgery.
I did not fare well after the surgery and was in the hospital for over a week. After that for month and months, I had lots of bowel troubles.
Enough to really change one's disposition. I was getting better but not much and the going was slow.
Our daughter had gone on an almost vegi diet (Dr. McDougal) and lost 40 pounds, and feels great.
Well I tried it, no animal fats, lactose free milk, no cheese, fish or eggs.
4 days later my colon was normal almost, and better than it had been for years. I also have lost 26 pounds and feel fine.