As for IBS getting better when removing gluten, this may be either due to “non-celiac gluten sensitivity” or to the fact that by eliminating gluten one also removes large amounts of FODMAP (Fructose, Olygosaccharides, Disaccharides, Monosaccharides And Polyols)-containing foods that are often causing or aggravating symptoms in IBS patients.
See also Barrett JS, Gibson PR. Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) and nonallergic food intolerance: FODMAPs or food chemicals? Therap Adv Gastroenterol. 2012 Jul;5(4):261-8.: http://www.ncbi.nlm.nih.gov/pubmed/22778791 June, 2013