It has many sharp edges that irritate and cut the delicate tissues within the gastrointestinal tract. That's because fiber does not help bowel movements. Our peristaltic nerves and muscles are the prime mover of the bowels. If the intestinal tract is nonfunctional, no amount of fiber is going to induce it to work. A healthy elimination pattern requires the bulk and fiber available only from a proper vegetarian diet.
Meat has very little fiber and fish has none at all.
Toxic substances such as refined flours, refined sugars, preservatives, condiments, rancid oil, etc., are the major cause of problems in the alimentary canal. Raw fruits and vegetables retain moisture and bind bulk for easy passage. I read the recent article on the Vista home school program. I was glad to see this in the newspaper since I am also home-schooled. But I was disappointed the you did not mention my school, Pacific View Charter School located in Oceanside.