Here's an interesting study that suggests the increase in IBS and Crohn's disease may be connected to the paucity of parasites in our current environment.  I call it the "Worms are Good for you" study!

More here.

This fits right in with the theory that the gut has a separate nervous system:  read my article on IBS for more.  I also wonder whether this may be why Larix (Arabinogalactans) are so helpful both for the immune system and the bowel.  And Primal Defense ( Homeostatic Soil Organisms). Beats eating worms!