There's a large amount of uc diets (paleo, SCD, diary-free, gluten-free, etc.) and uc supplements (fiber, probiotics, various seeds and oils) that people try. Like everything for this disease, things are highly individualized. Meaning what works for one person, doesn't necessarily work for another.
Both medication and non-medication (a.k.a alternative) approaches are mentioned in the Ulcerative Resources thread at the top of this forum. That would be a good place to start. Here's a direct link:
Ulcerative colitis resources