Take a look through this:
https://freerepublic.com/tag/ibd/index?tab=articles
I would suggest supplementing with 5 mg a day, but the Upper Tolerable Limit is 11 mg a day. We do get some from food.
My wife and I get over 30 grams of soluble fiber a day, primarily from newer keto bread options. We do add psyllium on top, as well.
I would also encourage considering a fast mimicking diet for five days, three months in a row.
I had to take some strong antibiotics about two years ago and was left with large intestinal pains. They have only recently basically gone. I did these things and also took probiotics. It would be similar for IBD, as you will note from the keyword search.
What is a fast mimicking diet?