they are high fiber and cause your waves of peristalsis to move faster and I'm not certain that the digestive system is entirely able to break them down that well.

hi, cool question... I don't entirely know the answer but I know that at least part of the reason is that those food are composed largely of a material called cellulose. Cellulose is cool, I'm pretty sure it's the most common organic mollecule in the world, it's what all wood, leaves, stalks etc. are made out of. It's composed entriely of glucose, the same subunits as starch, but even though starch and cellulose are composed of the same thing, the way they are linked together is very slightly different. The enzyme that our bodies produce to break down these chains of mollecules of glucose and use them is able to break the linkages in starch but NOT the linkages in cellulose. So while you et somthing starchy and it gets all broken up inside you and used, any part of it that is composed of cellulose (the covering of the little pieces of corn, for example) moves right through you body, untouched. It's pretty sweet. Anyway, The guy above is right, it's also called fiber but even though we all know what fiber is, I just think it's awesome to think about WHY it is that we can't use it. it's also awesome to think about the fact that this is ther reason that termites are able to eat wood and live off of it, becasue THEY produce the enzyme that we are not able to, which allows them to eat and digest and use cellulose. cool huh?

Not a direct duplicate, but I thought this might be of interest: http://www.answerbag.com/q_view/106001

One reason is that we do not masticate,or chew them long enough to make them into a mush.We swallow them in little pieces and they are not fully digested.

High fibre-corn, to digest it, you need lime!

Can't say that I've noticed that before. Sounds kinda gross.