Smoking does suppress crohns or colitis. You might want to try a nicotine patch instead though.
It's my theory that certain foods are difficult for people to digest. They get passed, undigested, into the colon, where bacteria turn them into flatulence. The bacteria get out of control and start eating though the lining of the colon, causing bleeding.
Nicotine suppresses the inflamation, but not the cause -- the food that doesn't agree with you.
What foods bother you specifically you can only find out through experimentation. For me, it's beef, sugar, pork, wheat and corn.
I'm on rowasa(mesalamine) enema's right now. If I eat "bad food", I won't bleed anymore, but I will get flatulence and diarrhea. It's good food + rowasa that gets rid of 99% of my symptoms.