Dietary changes are often a big help but they won't easily correct deficiencies that were worsened by the diarrhea, the reason being there aren't enough trace minerals like Iodine and selenium in even organic food
I believe supplementation of minerals is essential and eating specific foods very high in them.
I also believe Iodide in doses of at least a gram a day was the best thing for me, to stop bleeding and make the colon resistant to further ulceration, even with some dysbiosis still present.