Potatoes have been very beneficial for my UC symptoms, calms my gut down, makes it happy.
I prefer to get my supplements through food not by pill or powder but others here have used butyrate successfully.
The best place to see reliable information is from scientific studies.
I typed "NIH starch ulcerative colitis" and many references came up. here's one of many.
/www.ncbi.nlm.nih.gov/pubmed/17936196NIH is National Insitutes of Health and is reliable.