I think it is common in all literature and websites that ulcerative colitis requires attention to diet.
Here is a brief classification based on my experience.
[○ It was okay to eat, it didn’t affect me that much.
Sushi in general (excluding meat and shellfish other than fish)
Bread with no or little butter
Italian food (olive oil is okay, apparently)
Chicken (excluding skin and other fatty parts)
X Symptoms worsened after eating them.
Beef
Pork
Fried foods
Snack foods
Alcohol
Salad oil and lard were often worse. Olive oil did not affect me as much.
For a drinker like me, it is very hard to be aggravated by alcohol.
I can assure you that if you watch your diet, you will be healthier outside of your colon.