Have you tried doing any research on the net? There is an untold wealth of information, but of course it isn't in book form.
Just type your subject into a search engine.
Also - Mayo Clinic
Usually one link leads to another, etc. You just have to put forth a little effort and time. -:)
Good luck with your studies
Try looking up Celiac Disease or Celiac Sprue; Chrones Disease; Inflammatory Bowel Disease; and that great make-believe disease now given the name of IBS or Irritable Bowel Syndrome. IBS is a fabulous catch-all scapegoat for lazy doctors who are unwilling to perform the necessary investigations to get to the root of the patient's real problem. Anyone with a tummy ache these days gets diagnosed with IBS, and usually told that fiber will cure them forever. BAH HUMBUG!