Aark!!! I think you don't have IBS, you may have "celiac sprue".

Getting back to the original question: if your friend doesn't feel a lot better after a few months on the program for IBS, please get him/her checked out for celiac disease. It's a simple test apparently but the disease is WAY underdiagnosed in the US, though many many of European descent carry a gene for it.

A colleague suffered for a couple of years with bowel problems and lost 50 pounds and was looking cadaverish while taking tons of drugs and being put through nasty GI tests etc.   Somebody finally checked him for celiac. It was killing the little fibers in his intestines or colon or whatever to the point where they were no longer functioning, and apparently the diease had been progressing for years, the first several of which he had no idea.   The entire cure is avoiding wheat flours and glutens, I don't know the details. Which is why it sounds suspiciously like what Aark is having.