I think that FiberOne is psyllium. When I began to take Zelnorm, Perdiem, which is also psyllium, gave me enormous trouble with gas even though I had been taking Metamucil (another form of psyllium) for years. Someone on the board suggested avoiding psyllium all together. She suggested that I take Citrucel, which is not broken down by the gut. This eliminated a lot of problems for me. I would suggest that you eliminate psyllium and see if that helps. If FiberOne is made up of psyllium, try stopping it.Steven