The fiber would make me worse, not better, if I was flaring!
And some of that other stuff might also be more irritating than helpful, too, and it would be difficult to tell which.
Stick with the probiotics and a low-fiber diet?
In my view, supplements are mostly a waste of money.
I'm not surprised a nutritionist would suggest fiber as the cure-all. All the ones I've been to, that's all they know.
Ask them about a low-fiber diet and their eyes glaze over.