After a long series of having medical examinations and being talked down to by medical consultants, my wife was evetually diagnosed as having IBS. When she asked what that was, she was told "I suggest you go away and find out, my dear!". Subsequently, we found out it was the medical term for "we don't know what the problem is". Anyway, my wife finally made the discovery herself that she had the problem when she ate meat. So she stopped eating meat and the IBS went away. This does not mean, of course, that meat is the cause of IBS in other cases.