First comment is absolutely right. However the bacteria in our gut eat fiber so for a healthy gut it is important to eat plenty of high fiber foods. For insoluble fibers you can get them from beans, whole grains, green beans, cauliflower, potatoes, and nuts. It is hard to know which foods have which, your best bet would be to print out a cheat sheet of sorts that tells you which ones each food has. Something like this might help:
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