Metamucil is 100% natural psyllium fiber which is a source of soluble fiber. Psyllium fiber comes from the outer coating, or "husk" of the psyllium plant's seeds similar to fiber found in grains such as oats and barley. The amount of soluble fiber in psyllium is nearly 5X higher than that of oat bran.
100 grams of psyllium = 50 grams of soluble fiber
100 grams of oat bran = 5 grams of soluble fiber
So for this reason, trying to make it work in your diet to help with your IBS but with the sugar free variety since you would need to eat a lot of other soluble fiber sources to make up the difference. www.metamucil.com/metamucil-sugarfree-oran