While certain foods do not directly cause ulcerative colitis, they can exacerbate existing symptoms. Identifying and avoiding trigger foods can help reduce the frequency and severity of flare-ups. Commonly known foods that increase ulcerative colitis symptoms include alcohol, coffee, chocolate, dairy products, dried beans, dried fruits, popcorn, garlic, melon, and watermelon. This list may vary based on individual sensitivities and can be expanded.