Iron tablets and UC

My iron levels (yep, just like my cortisone levels) have been low. The Doctor put me on iron supplement tablets. I managed to stay on them only for 10 days as they seemed to play havoc with my insides. Just a few pains, nothing too major, but just enough to make to decide that I didn't want to take iron supplements. I'd heard before that iron supplements and UC we not a good combination, but I don't know why. I'll have to try and increase my iron levels by eating iron rich foods instead and see what happens.