Now, I am going to throw a different opinion out there. My family doctor, years ago told me that IBS simply means, I Be Stumped, that doctors really do not understand IBS, it's a catch disease just as many feel Fibro is. Over 30 yrs ago, I was diagnosed with spastic colon, IBS, nervous stomach, and too much stress all by the same gastro. I feel if IBS is a real syndrome, it's caused by food intolerances or med issues. NSAIDS cause leaky gut, which is what I actually have been suffering from for years and years. 30 years ago, leaky gut was never mentioned, nor were food issues. I have totally refined my diet and do not suffer the IBS symptoms any longer, only if I take the heavy meds. I can take the occasional ibuprofen or Aleve without issue, but taking anything on a daily basis causes my leaky gut to flare. I have not been able to get the leaky gut to heal simply because of the flares.
Here is an interesting link for you to read: http://www.mold-survivor.com/leaky_gut_syndrome.html