After smoking for 33 years, I quit in May 2001. For a few years before that, I'd had what I thought was gall bladder problems and IBS, and by Sept. 2001, I was in bad enough shape that my HMO finally figured out that I needed my gall bladder removed. I still had and have pain in that area, though. I think it's all related to my UC but somehow I didn't have the last key symptom of bleeding until last year, after an extremely stressful period. So smoking may have kept my UC at bay for 15 or more years, who knows?
That said, I would never think of picking up a cigarette again. The damage they cause is so much worse than what they can help.
I used Quitnet.com for support when I quit, rewarded myself with massages and funnelled my energy as much as I could into exercise. I didn't start yoga until a few years later but I wish I had before I quit. Yoga breathing is very helpful, for quitting smoking and for getting through some of the urges and cramping etc of UC.