I do not believe that any of the diet stuff can be stated as fact, nor can we go to our gasteroenteroligists and expect him/her to prescribe a diet as confidently as mesalamine. As there's very limited, small-scale,
open-labeled studies for diets. That level of scientific scrutiny isn't very solid, as that's known for a lot of exaggerated placebo effect. Rather, a study has to be large-scale, double-blind, placebo-controlled, and peer verified to be solid and reliable. So, for liability reasons your/my gastereoenteroligist will not recommend diets. At this point diets are pretty experimental with no guarantee of success. Here's pretty much everything that's known about
diets and UC at the moment: https://www.dietvsdisease.org/ulcerative-colitis-diet/
I understand some believe diet has helped them personally, we're happy for you and celebrate all successes (as flares bitterly suck). However, a few success stories only amounts to hearsay and anecdotal evidence, not something solid and broadly recommended by all gasteroenteroligists for everyone's treatment of an UC. I know some of us are so inclined to try diets, that's fine, they're generally considered do-no-harm. It's a lifelong illness and some of us want to try things like that, or anything that might have a chance of helping us with symptom relief. I'd always carry a healthy skepticism, try it for a month, and verify results.
I know the CCFA is running some more diet studies, and I eagerly await those results. I'm deeply curious about
diets and hope they work, but the jury is still out on that one...