A pair of gut bacteria may cause constipation

By Jackie Flynn Mogensen edited by Claire Cameron

It is as unfortunate an ailment as it is ubiquitous: at some point in our lives, we will become constipated. Our gut is a delicate flower, and sometimes it just can’t cope with the even slightest of changes to our diet or environment: low water intake, not eating enough fiber, a sedentary lifestyle, medications and more can prevent you from going.

Gut bacteria are crucial to ensuring healthy digestion and defecation. But two species of bacteria may also be the cause of constipation: according to a new study, Bacteroides thetaiotaomicron and Akkermansia muciniphila appear to work in concert to break down colonic mucin, the slimy coating in our colons that keeps our poo moving along. Too little mucin means a drier and more constipation-prone colon.

“What excites me most about this study is that we’ve identified a specific mechanism by which gut bacteria can cause constipation,” says Tomonari Hamaguchi, a lecturer at Nagoya University in Japan and the lead author on the study. He notes that constipation causes some 2.5 million doctor visits every year in the United States.

On supporting science journalism

If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

“Yet for many patients, current treatments provide only temporary relief because the underlying cause remains unknown,” he says.

In the study, which was published this week in Gut Microbes, the researchers modified one of the bacteria, B. thetaiotaomicron, preventing it from breaking down mucin. They then transplanted it and the other bacterium, A. muciniphila, into mice.

Interestingly, the mice’s colon mucin stayed intact. And the mice remained regular, with no signs of constipation. The findings indicate that both of the bacteria together, and not just one or the other, pose a threat to mucin.

It’s unclear how widespread these bacteria are in people, but the results could open the door to new treatments for chronic constipation, especially for people who find no relief with the drugs and remedies already on the market. According to one estimate, as many as one in five people in North America may have chronic constipation, and its more common in women and in the elderly.

“Not all constipation has the same cause, and if we can identify patients with this bacterial mechanism—for example, by measuring fecal Akkermansia levels as a biomarker—we may be able to move toward personalized treatment strategies instead of one-size-fits-all laxatives,” Hamaguchi says.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.