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Blue Sky Science: What's the purpose of the appendix?
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Blue Sky Science: What's the purpose of the appendix?


Editor’s note: This Blue Sky Science feature on the appendix originally appeared in the Aug. 10, 2015, Wisconsin State Journal.

Q What is the purpose of the appendix?

— River Heisler, Brandeis University

A: For decades, scientists and physicians have believed the appendix really doesn’t have a function in human beings. It may have had a purpose in some living thing tens of thousands of years ago, but that purpose never persisted in humans.

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At least that’s been the thinking until recently.

Common sense seems to back up that theory. About 7 percent of Americans have had their appendix removed, and most people do fine afterward.

But research has suggested the appendix may help people retain the natural bacteria that inhabit our intestine. A very severe bacterial infection that causes diarrhea, known as dysentery, can wipe out the “good” bacteria in a person’s system. It’s been postulated that this bacteria can be repopulated, once the infection clears, because it has been housed in the appendix. Dysentery is rare in the U.S. but is still a problem in developing countries.

There’s probably also a lymphatic or an immune function to the appendix. We have seen white blood cells and other types of immune cells in the appendix. And sometimes when people get their appendix removed, they’re at increased risk for Crohn’s disease, which is an autoimmune condition of the bowel.

When people develop appendicitis, they really haven’t done anything bad to get the condition. It’s just kind of a bad break.

There really isn’t some preventive medicine or healthy living to promote your appendix.

Dr. John Williams is a gastroenterologist at UW Health.

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Blue Sky Science is a collaboration of the Wisconsin State Journal and the Morgridge Institute for Research. The questions are posed by visito…

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