‘Bad guys’ in the gut: Archaea overgrowth linked to severe constipation
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Key takeaways:
- The prevalence and severity of constipation was higher in patients with intestinal methanogen overgrowth.
- Conversely, rates of diarrhea and nausea were lower in these patients.
The prevalence and severity of constipation was significantly higher in patients with intestinal methanogen overgrowth, underscoring the importance of diagnostic and treatment strategies specific to archaea overgrowth, researchers wrote.
“Archaea are the oldest form of life on our planet and are the only living organisms that can produce methane,” study author Ali Rezaie, MD, MSc, medical director of the GI Motility Program and director of bioinformatics at the Medically Associated Science and Technology program at Cedars Sinai, told Healio. “Classically, we have a good understanding of what viruses or bacteria cause what diseases, but we know much less about archaea. It is interesting that intestinal methanogen overgrowth, an excessive amount of methane-producing archaea in our bowels, is the first instance where archaea behave as bad guys.”
According to Rezaie, patients with intestinal methanogen overgrowth (IMO) exhibit a “constellation of symptoms” related to the GI tract, including flatulence, change in bowel habits and bloating. However, less is known about the phenotype of patients with IMO, which could be the focus of future studies to improve care.
In a systematic review and meta-analysis published in Clinical Gastroenterology and Hepatology, Rezaie and colleagues analyzed data from 19 studies, which included 1,293 patients with IMO and 3,208 controls, to better understand the association between various GI symptoms and IMO.
According to the researchers, bloating (78%), abdominal pain (65%), flatulence (56%), constipation (51%), diarrhea (33%) and nausea (30%) were among the most prevalent GI symptoms reported in patients with IMO.
Results also showed that patients with IMO demonstrated a significantly higher prevalence of constipation vs. controls (47% vs. 38%; OR = 2.04; 95% CI, 1.48-2.83), but lower prevalence of diarrhea (37% vs. 52%; OR = 0.58; 95% CI, 0.37-0.9) and nausea (32% vs. 45%; OR = 0.75; 95% CI, 0.6-0.94). In addition, patients with IMO experienced more severe constipation (standardized mean difference [SMD] = 0.77; 95% CI, 0.11-1.43) but less severe diarrhea (SMD = –0.71; 95% CI, –1.39 to –0.03).
In a related Cedars Sinai press release, the researchers noted that treatment for severe IMO-induced constipation includes suppression of archaea overgrowth with a combination of antibiotics and a specialized elemental diet.
“With the identification of excess methane as a biological marker, we can now use precision medicine to tailor treatments specifically for this group of patients, rather than relying on the empirical therapies traditionally used for all constipation cases,” Rezaie told Healio. “I believe the future of treating microbiome-dependent disorders lies in a biomarker-based precision medicine approach.”
Reference:
- Gut microorganism may play a role in constipation. https://www.cedars-sinai.org/newsroom/gut-microorganism-may-play-a-role-in-constipation. Published Aug. 29, 2024. Accessed Sept. 06, 2024.
Perspective
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Anthony Lembo, MD
IMO is characterized by an excessive presence of methanogen-producing archaea, which differ fundamentally from bacteria in that they produce methane gas.
Unlike small bowel bacterial overgrowth (SIBO), IMO appears to involve both the colon and the small intestine. While methanogens are normally present in the gut microbiome in small quantities and aid digestion, an overgrowth can disrupt GI function, leading to symptoms such as bloating, constipation and other GI disturbances.
The study findings align with previous preclinical model studies showing that methane production affects intestinal motility, slowing intestinal transit and reinforcing the unique clinical profile of IMO compared with hydrogen-based SIBO.
The study advocates for integrating methane detection into GI assessments for patients presenting with constipation-dominant symptoms, as it could aid in more accurate diagnosis. It also highlights the need for safe and effective treatments for IMO.
Future studies should evaluate potential treatments tailored specifically to IMO. While studies have shown promise with dietary interventions, combination antibiotics and prokinetic agents, additional research is needed to establish optimal regimens, safety and efficacy.
Recognizing IMO as a distinct clinical entity, rather than simply a subtype of SIBO or irritable bowel syndrome, is essential. Increased awareness, enhanced diagnostic precision and targeted treatments are vital steps forward.
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