Hello! I am new to the forum and just wanted to share an excellent resource:
The Innate Health Foundation is a public charity created to support the Irritable Bowel Syndrome and Food Allergy communities. Their website at www.InnateHealthFoundation.org has great information on IBS, including a page devoted to published medical research on the causes of IBS and how to treat them. That page is at www.InnateHealthFoundation.org/5_c.htm
The research director of the Innate Health Foundation wrote an excellent book on the subject called 'The Irritable Bowel Syndrome Solution' by Dr. Stephen Wangen. It is available on Amazon.