You may have had your appendix removed because doctors believed that it was a useless vestigial organ. Now researchers have found that it serves as a storage tank for healthful germs that live in your intestines. These good bacteria help to break down food so you can absorb its nutrients. They also prime your immune system to recognize harmful germs and prevent them from invading your body, prevent your immune system from attacking your own body to cause auto-immune disease, and produce immune factors that may prevent colon cancer ( Microbiology, February 9, 2009).
When you have diarrhea, bad bacteria can remove the good bacteria in the intestines and colon. A study from Duke University shows that the bad bacteria cannot dislodge the good bacteria from the appendix because its inner lining is covered with a thicker and far more potent biofilm (a layer of bacteria, mucous and immune system cells) than is found in the intestines (Journal of Evolutionary Biology, August 2009). No matter how severe the diarrhea or how extensively the bad bacteria drive out the good bacteria from the intestines, the good bacteria persist in the appendix and eventually re-colonize the rest of the intestines. More on good bacteria