Unable to digest fibre. Excessive gas, abdominal distention, pressure and pain. Dwells in my system for hours. Fibrous food remain undigested in stool?

Fermented... Many fibers, particularly the water insoluble kind, are readily fermented by your gut flora. Some people have certain intolerances to bean husks (try beano), to wheat/barley/rye (gluten sensitivity), &/or have a particularly active population in their gut of gas-forming organisms (try bifidobacter-containing probiotics). Maybe altered GI motility, ibs, air swallowing, maldigestion/malabsorption?