Hi - Cheerios are whole oats, and oats do have both soluble and insoluble fiber. Check the box label - it will probably give you a breakdown. Oats (and brown rice) are among the most tolerable whole grains for IBS, but not everyone does well with these, so just pay attention when you eat them.If you take Citrucel and you're not used to it, it can cause gas and bloating. Increasing your dose too high, too quickly, can definitely cause gas and bloating. If you're well-adjusted, you could still take too much if you really abuse the dosages, and the result would be GI upset and also a risk of not absorbing nutrients from your food. I wouldn't take more than 15 grams of any soluble fiber supplement daily without asking your doc first. Odds are you could go somewhat higher than this, but I don't know what the cut-off would be.- Heather