How methane gas went from just a symptom to a cause of IBS-C


Most gastroenterology physicians believe methane gas is a by-product of IBS. People diagnosed with IBS tend to produce methane, which leads to the common complaint of abdominal pain, bloating, and constipation. The assumption that IBS causes methane production seemed logical.


For those not familiar with methane, it is a colorless gas that humans expel through flatulence or exhaling. When people eat fiber or other forms of complex carbohydrates, the bacteria in the gut ferment the fiber and produce hydrogen. Microorganisms feed off on the hydrogen, which then releases methane.


But a growing body of research is now confirming that methane may be more important than just an IBS symptom. In an article published in Cureus Journal of Medical Science, authors Syed Hamza, Bin Waqar and Aiman Rehan have reviewed and analyzed all literature on IBS and methane and summarized their findings. They hope that by emphasizing the important role of methane in disorders like IBS-C, it might spur others to continue research in this area.


In a review of several studies published, the authors say that there is enough evidence to confirm that methane is a neurotransmitter, meaning it plays a key role by sending signals to and from the gut. One study showed it can influence how stool passes through the colon. Another indicates that it can signal how the small intestines contracts.


The bacteria that makes methane

The gut is home to hundreds of millions of microorganisms, many of which help digest food, regulate the immune system, protect against certain diseases, and produce vitamins. The number and types of bacteria differs from person to person and is influenced by genetics, the environment, antibiotic use, and other medical conditions.


There are several types of bacteria that researchers have known to contribute to methane levels in the gut. However, the organism Methanobrevibacteri smithii is responsible for more than 90% of the methane production. These microorganisms are similar in size to bacteria, but their cell wall structure is different, so most antibiotics are not effective in eliminating the bacteria and relieving symptoms.


While most bacteria in the gut tend to live in the colon, sometimes they creep into the small intestine, causing a condition known as small intestinal bacterial overgrowth (SIBO). When methane production occurs in the small intestinal tract, the same symptoms (bloating, pain, constipation) still occur, but now because it’s in the small intestines, it can be easily detected on breath tests.


This is important because previously, few knew about the link between methane and SIBO. Also, until breath tests came about, testing for SIBO was invasive and expensive.


Methane is specific to IBS-C

It appears that methane is more specific to IBS-C than other types of IBS. While there are individuals with IBS-D or IBS-M who complain of bloating and abdominal pain, research led by GI specialist Mark Pimentel, MD, points to methane as the culprit behind the development of IBS-C. Methane has been seen as not only the cause of constipation or functional problems of the gut, but it can also influence whether a person suffers from mild, moderate, or severe constipation.


It appears that certain individuals are prone to producing more methane gas than others. Neurogastroenterologists call them “methane producers.” Reducing the level of bacterial fermentation may, in theory, reduce the availability of hydrogen that can be converted into methane. While studies have been done on incorporating low FODMAP diet to reduce the levels of gas among methane producers, not enough studies have shown that they work.


What’s next with methane research?

With a greater understanding on the role that methane plays in IBS researchers can narrow their search for new therapies, such as:

  • A spot methane breath test to diagnose patients with IBS-C

  • Personalized therapies specific to those who are high methane producers

  • New therapies that will target the methane-producing bacteria without impacting other organisms living in the gut

  • Repurpose certain medicines, such as the cholesterol-lowering drug, lovastantin, for preventing or reducing the production of methane



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