Yeah probiotic can do a little (sometimes) I've tried over 15 brands and they are all rather worthless. There isn't some quick fix in a pill. Fermented foods are way important and far more helpful than any probiotics.
IBS heals significantly with good fat (meaning raw saturated fat) Not cooked, not frozen or chemically extracted or created. Real food does heal. How would i know, 5 years with very severe IBS/Crohns Disease...I'm now free of the disease and recovering from the severe malnutrition I experienced.
There is more to it than the above...but most people aren't interested, i still don't really understand why. I guess breaking "status quo" is too hard.