After decades under a label that marked it as superfluous, the appendix may finally be able to justify its existence. Doctors at Duke University Medical School found the appendix protects beneficial bacteria living in the human gut.

The study, published last week in the online Journal of Theoretical Biology, found the appendix works to repopulate bacteria that help digest food after a disease such as cholera or dysentery wipes it out.

"While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed," said Duke surgery professor William Parker, in a press release.

Parker conducted the analysis in collaboration with Duke surgery professor R. Randal Bollinger.

The pair found that a biofilm, a thin layer of microbes, mucous and immune system molecules lining the intestines, protects the bacteria in the appendix.

The appendix "acts as a good safe house for bacteria," said Parker. The location of the appendix just below the normal one-way flow of food and germs in the large intestine in a sort of gut cul-de-sac helps support the theory, he said.

The organ outgrowth acts like a bacteria factory, cultivating the good germs, Parker said.

"Once the bowel contents have left the body, the good bacteria hidden away in the appendix can emerge and repopulate the lining of the intestine before more harmful bacteria can take up residence," Parker said.

He said the appendix is not really needed in a modern society because people are able to pick up the needed germs from other people, so there are few negative effects if it is removed.

With files from the Associated Press