Mikeey, there are two kinds of fiber, and they don’t behave the same way at all, particularly for J-pouchers. Soluble fiber is found in oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables. It is also found in psyllium, a common fiber supplement. Some types of soluble fibermay help lower risk of heart disease. Insoluble fiber is found in foods such as wheat bran, vegetables, and whole grains. Many foods (like prunes) have a mix of both kinds of fiber. Prunes also contain sorbitol, which I avoid like poison, though I’d eat them if I were constipated.
I take extra soluble fiber every day, in the form of psyllium. I’m more careful with insoluble fiber, though I enjoy that, too. Insoluble fiber is the one with the greater tendency to soften stool, which most J-pouchers don’t need.