Hi,
I have had ulcerative colitis and my sister has it too plus chron's for over 10 years. If by supplements you mean diet pills, I wouldn't. Probiotics are great, and fine, but nothing stimulating which all diet pills are to an extent. Other supplements, like fish oil and even vitamins can bother you, but are not harmful. Check to see if they have a "bleeding" warning on them like ibuprophen does, those are a no-no. Your best bet unfortunately is the old, diet and exercise. I was just last night wishing I could take a pill. They never work.
good luck, Karen