Gut Microbes Linked to Constipation

A new Cedars-Sinai study shows how microorganisms in the human gut can trigger constipation in some people.

The study, published in Clinical Gastroenterology and Hepatology, showed that disruption in a patient’s gut flora, specifically the overgrowth of archaea—unique microorganisms in the gut microbiome that produce methane—could be the cause.

Researchers hope the study’s findings will help experts root out the cause of constipation instead of merely treating patients’ symptoms. These findings could also aid in developing a personalized treatment plan for a subgroup of patients who experience severe constipation due to intestinal methanogen overgrowth (IMO)—a condition in which archaea excessively grow in the intestines.

“Our study found that patients with IMO are more likely to have constipation, particularly severe constipation, and less likely to have unyielding diarrhea,” said the study’s corresponding author, Ali Rezaie, MD, medical director of the Cedars-Sinai GI Motility Program and director of Bioinformatics at the Medically Associated Science and Technology (MAST) program at Cedars-Sinai. “Patients, however, also reported several other gut-related symptoms, including bloating, diarrhea, abdominal pain and flatulence.”

Constipation is one of the most common gut-related issues in the United States. About 16% of adults experience bloating, abdominal pain, and difficulty having bowel movements; the numbers nearly double for people over 60. While many things, like medication side effects or lack of dietary fiber, can cause constipation, historically, there has been a shortage of research on the gut microbiome’s role in constipation and other digestive issues.

“When there is an excessive amount of archaea in your gut, they produce more methane, and some of that methane makes its way to your bloodstream, then to your lungs, and you breathe it out, where it can measured as a diagnostic test,” Rezaie said. “Essentially, people who have excessive amounts of methane have a lot of GI symptoms, including constipation, flatulence, bloating and diarrhea.”

For context, the gut microbiome consists of trillions of microorganisms, such as the community of bacteria, yeast and fungi in the digestive system. When there is an imbalance among the microorganisms populating the gut, it is associated with a host of GI symptoms and diseases.

Experts used electronic databases to identify 19 studies—11 conducted in the U.S. and eight conducted in six other countries—that assessed symptoms for patients with IMO.

“Historically there has been a paucity of information regarding the role of archaea in health and disease. Unique symptom patterns related to IMO should be taken into account when measuring patient-reported outcomes and should be further studied in relation to the microbiome,” said Peter Chen, MD, interim chair of the Department of Medicine at Cedars-Sinai.

For example, taking over-the-counter or prescription laxatives often relieves constipation, but won’t always address other GI symptoms, such as bloating, abdominal pain and diarrhea. In fact, in some cases, taking a laxative could potentially worsen coexisting diarrhea and bloating.

Researchers explain that the optimal solution for IMO-induced severe constipation is to suppress the archaea overgrowth and keep the organism at bay. This generally involves a combination of antibiotics and a specialized diet to reset the gut microbiome. However, the first step is to diagnose the archaea overgrowth through a noninvasive hydrogen/methane breath test.

According to Rezaie, the study's findings are crucial and will hopefully encourage healthcare providers to utilize precision medicine, conduct clinical trials that target microbiome research and develop strategies to optimize patient care.

“The goal is to move toward developing specific therapies and personalized treatment for a subgroup of people who experience constipation due to IMO,” Rezaie said. “We can start by using breath tests to identify excessive methane production, which can be the first step to detecting archaea overgrowth and could ultimately lead to developing more targeted therapies. It's a big step to move away from the common reflex use of laxatives.”

Reference: Mehravar S, Takakura W, Wang J, Pimentel M, Nasser J, Rezaie A. Symptom profile of patients with intestinal methanogen overgrowth: A systematic review and meta-analysis. Clin Gastroenterol Hepatol. doi: 10.1016/j.cgh.2024.07.020

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