Methane Dependent Bacteria and SIBO
Unique gut bacteria could target a common cause of functional constipation, methane producing bacterial overgrowth, according to a new study. Recently it has become apparent that a common cause of constipation is overgrowth of methane producing bacteria known as methanogens1. Overgrowth of the methanogen Methanobrevibacter smithii increases gut methane levels which directly inhibits gastrointestinal motility and results in clinical symptoms of constipation2. It’s not technically bacteria, but single-celled organisms called archaea. Targeted reduction of methanogens with antibiotics has been shown to improve gut transit and constipation, but treatment alternatives are needed.
A research group from the University of the Sacred Heart, Rome, and Columbia University Medical Center, NYC, hypothesized that a unique probiotic strain - Lactobacillus reuteri DSM 17938 - may be able to reduce gut methanogens and improve bowel movements in people with constipation3.
Testing their idea in people with constipation predominant irritable bowel syndrome (IBS), they found that prescribing Lactobacillus reuteri DSM 17938 (100 million CFU) 30-minutes after eating twice daily for 4-weeks significantly decreased methane gas production, as determined by a lactulose breath test. The reduction in methane production was associated with a significant increase in bowel movements and regularity.
“Our hypothesis is that L. reuteri DSM 17938 may inhibit gut microbiota gram-positive bacteria more than negative, shifting gut microflora towards dominant hydrogen consuming microorganisms,” concluded the investigators. “The possibility to reduce methane production with the administration of L. reuteri DSM 17938 could then represent the basis for new and more effective therapies even for other gastrointestinal disorders linked to methane production.”
When people eat fibre, the gut bacteria ferments it and produces hydrogen. This is what archaea feed off. It is only once the archaea consume the hydrogen that they produce their own by-product: methane. To support a large amount of archaea (i.e. an overgrowth), there must be sufficient hydrogen to feed them. For any person who has tested positive for methane small intestinal bacterial overgrowth (SIBO), this means there is an overgrowth of bacteria (SIBO) which produce excess levels of hydrogen. Also, though there may not be an overgrowth of hydrogen-producing bacteria, excess hydrogen levels may not show up on testing as the archaea consume the hydrogen and produce methane instead. As with hydrogen in the small intestine, methane gas will also cause abdominal bloating, plus a much bigger problem; it slows down transit time which leads to constipation4.
Higher levels of breath methane are also linked with obesity in humans. This is thought to occur via a couple of mechanisms. First, archaea have been shown to affect the amount of calories your body absorbs by increasing the capacity of gut bacteria to digest specific glycans. And secondly, previous studies have demonstrated that methane gas slows small intestinal transit time, which may contribute to increased weight gain by increasing the amount of time during which energy is extracted from meals.
Cutting the food supply to the archaea is an important step in the process. And because archaea feed off hydrogen, this means reducing hydrogen-producing bacteria is critical. After all, the archaea may only be thriving because they have so much hydrogen to consume because of a more traditional bacterial overgrowth. Using antimicrobials that target both bacteria and archaea in the small intestine are recommended. This also means reducing fermentable carbohydrates and fibre in the diet initially is also a good idea. Methanogenic archaea are unfortunately resistant to the majority of antibiotics that are commonly used against bacteria.
An estimated 75% of bacterial infections, and possibly higher in archaeal infections, involve biofilms. Biofilms are colonies of microorganisms that are protected by an extracellular matrix. This protective home makes the infection much more resistant to antibiotic therapies and therefore, more difficult to kill. This is why a comprehensive antimicrobial SIBO treatment protocol should include the use of a biofilm disrupting agent.
It is often advisable to use a prebiotic, called partially hydrolysed guar gum (PHGG), to help feed good bacteria that are anti-inflammatory, improve transit time and restore balance to the small intestine. Feeding the good guys, such as anti-inflammatory butyrate and bifidobacteria, and encouraging the right balance of flora is an important part of the long-term healing journey. There is obviously a delicate balance here and prebiotics are something that needs to be introduced slowly.
In a healthy person minute amounts of sulphur is converted into hydrogen sulphide. Hydrogen sulphide is necessary because it is an endogenous cellular signalling molecule. Hydrogen sulphide overgrowth mainly occurs in the upper gut but can cause SIBO as well. H. Pylori are a major source of hydrogen. Many bacteria that produce hydrogen sulphide from sulphur and thiol ingestion colonize the upper gut. Common symptoms of hydrogen sulphide overgrowth include:
- Sulphurous Flatulence and Defecation.
- Chronic Fatigue Syndrome, Elevated Hydrogen Sulfide is Toxic to the Mitochondria.
- Brain Fog and Short Term Memory Loss
- Intolerance to Sulphur Containing Foods, Supplements, and Medications
- Constipation(Most People With Upper Gut H2s Overgrowth Also Have Methane Dominant Archaea as a Secondary Overgrowth in the Small Intestine)
- Digestive Tract Inflammation, Irritation, and Ulceration.
- Leaky Gut(Too Much Hydrogen Sulphide Reduces Butyrate Oxidation, Increases Inflammation, and Starves the Gut Enterocytes, Leading to Leaky Gut)
- Inflammatory Bowel Disease
If too much hydrogen sulphide is produced in the microbiome natural ways of detoxifying it in the gut are overwhelmed. The element molybdenum is also important for sulphur metabolism in the body, deficiency in molybdenum causes sulphur metabolism issues.
- 1. Gottlieb K, Wacher V, Sliman J, Pimentel M. Review article: inhibition of methanogenic archaea by statins as a targeted management strategy for constipation and related disorders. Aliment Pharmacol Ther. 2016 Jan;43(2):197-212.
- 2. Ghoshal U, Shukla R, Srivastava D, Ghoshal UC. Irritable Bowel Syndrome, Particularly the Constipation-Predominant Form, Involves an Increase in Methanobrevibacter smithii, Which Is Associated with Higher Methane Production. Gut Liver. 2016 Nov 15;10(6):932-938.
- 3. Ojetti V, Petruzziello C, Migneco A, et al. Effect of Lactobacillus reuteri (DSM 17938) on methane production in patients affected by functional constipation: a retrospective study. Eur Rev Med Pharmacol Sci. 2017 Apr;21(7):1702-1708.
- 4. Pimentel M, et al. Methane, a gas produced by enteric bacteria, slows intestinal transit and augments small intestinal contractile activity. Am J Physiol Gastrointest Liver Physiol. 2006 Jun;290(6):G1089-95. Epub 2005 Nov 17.
- 5. Carol Potera ANTIBIOTIC RESISTANCE: Biofilm Dispersing Agent Rejuvenates Older Antibiotics, Environ Health Perspect. 2010 Jul; 118(7): A288.