I sufffered with this for over 12 years i had the diarrhea type and had to plan my life around where was the toilet.
One thing that helped was taking Calcium supplements. I took a 200mg Caltrate Plus before every meal, and one at night. Within 7 days, my IBS had reduced a good 35% which was a great improvement.
What finally cured it, was after suffering so long i was dx'd w/ a giant fibroid tumor. After my hysterectomy, no more IBS.

Boo Radley