Appendix - not so useless an organ as we thought

Appendix – not so useless an organ as we thought

 

Some scientists think they have figured out the real job of the troublesome and seemingly useless appendix: It produces and protects good germs for the gut.

 

That is the theory from surgeons and immunologists at Duke University Medical School, published online in a scientific journal.

 

For generations the appendix has been dismissed as superfluous. Doctors could find no function for it. Surgeons removed them routinely. People live fine without them.

 

And when infected the appendix can turn deadly. It becomes inflamed quickly, and some people die if it is not removed expeditiously.

 

The function of the appendix seems related to the massive amount of bacteria that populates the human digestive system, according to the study in the Journal of Theoretical Biology. More bacteria inhabit the typical body than human cells. Most of the bacteria are good and help digest food.

 

But sometimes the flora of bacteria in the intestines die or are purged. Diseases such as cholera or amoebic dysentery would clear the gut of useful bacteria. The appendix's job is to reboot the digestive system in that case.

 

The appendix "acts as a good safe house for bacteria," said Duke surgery professor Bill Parker, a study co-author. 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.

 

Also, the worm-shaped organ outgrowth acts as a bacteria factory to cultivate the good germs, Parker said.

 

That use is not needed in a modern industrialised society, Parker said. If the gut flora dies, they usually can be repopulated easily with germs picked up from other people, he said. But before dense populations in modern times and during epidemics of cholera that affected a whole region, it was not as easy to grow back that bacteria, and the appendix came in handy.

 

In less developed countries, where the appendix may be still useful, the rate of appendicitis is lower than in the United States, other studies have shown, Parker said.

 

The appendix, which is about 6 to 10 centimetres long, may be another case of an overly hygienic society triggering an overreaction by the body's immune system, he said.

 

Even though the appendix seems to have a function, people should still have them removed when they are inflamed because it could turn deadly, Parker said.

 

Five scientists not connected with the research said that the Duke theory makes sense and raises interesting questions.

 

The idea "seems by far the most likely" explanation for the function of the appendix, said Brandeis University biochemistry professor Douglas Theobald. "It makes evolutionary sense."

 

The theory led Gary Huffnagle, a University of Michigan internal medicine and microbiology professor, to wonder about the value of another body part that is often yanked: "I'll bet eventually we'll find the same sort of thing with the tonsils."