Crohn's sufferer here. I have lost track of the times people have said "I tried this diet, and then my Crohns / UC went away".. and then some time later their symptoms reappeared. My understanding (via own reading and discussion with my doctor) is that there is just as much evidence against as for a meat-based diet .... or any kind of diet.

As my specialist put it "if there was a common diet that cured people, we would know about it already". Anecdotally one never knows if their UC/Crohn's improves because of their diet or it's just part of the ups and downs of those diseases.

That said, I'm happy in general if I hear a fellow UC / Crohn's sufferer seems to have found something that works for them, especially something that is better for you than steroids and other treatments with severe side-effects.