All fiber is not the same. I have IBS (irritable bowel syndrome), and one of the things I've had to learn is the difference between soluble and insoluble fiber. For many people, eating a lot of both is a good thing. For me, insoluble fiber irritates my digestive system, but my doctor told me that I couldn't eat enough soluble fiber. Foods high in insoluble fiber include fruits and veggies with tough skins (grapes, apples, some beans, etc.), and wheat bran. This part sometimes sucks because I love apples, grapes, etc. One time I actually found myself chewing on grapes and spitting out the skins. I tend to eat mostly cooked veggies and cooked or peeled fruits to aid digestion. Foods with soluble fiber include oatbran, flax seed meal, lentils, root veggies, avocados, etc. I also take psyllium husk supplements. (Psyllium is a plant from India and the husks are pure soluble fiber--the active ingredient in Metamucil.) Anyway, watching my intake of insoluble fiber and upping my intake of soluble fiber has helped me to reduce gas, diarrhea and stomach pains. Maybe you could try this out?