Many ways. Depends on type of colitis (infectious, inflammatory, ischemic), location of disease (rectum, left sided, entire colon), duration of disease and other meds that have been tried in the past. See a gastroenterologist or head to a tertiary center for a second opinion if you are not improving on current therapy and you have communicated this with your md. There are good therapies, assuming ibd cause.
Paleo diet. The best way to heal colitis is by completely stopping high carb foods (grains, lentils, potatoes based items). Avoid nightshades (peppers, tomatoes, eggs), milk protein since they cause inflammation Healthy foods: fish, meats, vegetables, avocados, some saturated fat (butter, coconut oil), olive oil are very effective. Take vitD3 10k IU/day, Probonix. You should feel a difference in 1-4 months.