i think citrucel is better than metamucil for this kind of thing. however for C people, they say flax fiber is best b/c it has 50% soluble and 50% insoluble - which is supposed to be the best mixture as eating too much soluble fiber can cause problems. i know i tolerate insoluble fiber better than soluble and regardless of what flux says, it seems to effect less gasiness or gassy feeling one way or another. maybe soluble fiber doesn't produce any more gas than normal foods - but maybe it pushes it through differently and therefore causes discomfort especially in those with ibs and the appearance of more having more gas. don't know. if you feel bad, then try something else. i'd recommend insoluble,but since you have D that may cause problems too. i'd say play around a bit - but i hear metamucil is the worst fiber for ibs-ers.