Hi Joe,
I was hoping someone else would jump on here to help but here it is...
Fibre has the ability to keep water. If there is low fibre in the lg
intestine, excess water will be absorbed out of the lg int and back
into the body. this leave dehydrated feces...ie) constipation
This is why people eat veges, fruit, and fibre supplement
Diarrhea arises when the muscles of the lg int are irritated. this
could be from infection or nervousness. Either way peristalsis occurs
more frequently and the water/ feces are pushed along faster than the
water can be absorbed. Now the excess water/feces are
excreted...diarrhea
Hope this helps!
Harkness