By Sarah Bloor, Clinical GI Physiologist
Methane gas is produced by microorganisms called methanogens, which colonise the digestive tract in humans. The methane crosses into the blood and is carried to the lungs where it can be exhaled in breath. Breath methane is detected in around 30%-50% of the healthy adult population3.
However, elevated breath methane is associated with bloating, gas, and constipation-related diseases, such as constipation predominant irritable bowel syndrome (IBS-C) and functional constipation4. Methane gas slows intestinal transit time, which may contribute to the development of constipation5.
Research shows that higher levels of breath methane production correlates with greater severity of constipation6. Higher levels of breath methane are also associated with obesity and reduced weight loss following bariatric surgery7,8. Methanogens may influence the amount of calories your body absorbs by increasing the bacterial production of short-chain fatty acids (SCFAs) in the colon9.
The methanogen thought to predominantly overgrow in humans is a species of archaea called Methanobrevibacter smithii10. Since methanogens may overgrow in the small bowel or colon, we call this intestinal methanogen overgrowth11. This can be diagnosed by a Methane Breath CH4ECK™ test.
- Positive: ≥10 ppm
- Inconclusive: 4-9 ppm
- Negative: <4 ppm
What does a positive test mean?
Breath methane levels of ≥10 ppm are considered ‘methane-positive’1. This is indicative of intestinal methanogen overgrowth.
What should I do if my test is positive?
It may be useful to discuss your results with a healthcare practitioner who is familiar with the management of intestinal methanogen overgrowth, such as a gastroenterologist or registered dietitian. If you undergo treatment for methane, it is easy to repeat the Methane Breath CH4ECK regularly to see if your methane has been reduced/eradicated.
What does an inconclusive test mean?
Breath methane levels of ≥4 ppm at baseline are predictive of those who will be diagnosed as ‘methane positive’ on a complete lactulose breath test (i.e. produce breath methane levels of ≥10ppm)2. Therefore, methane values of 4-9 ppm are inconclusive.
What should I do if my test is inconclusive?
A follow up lactulose breath test is recommended to confirm a positive result for intestinal methanogen overgrowth. However, this would require a referral from a healthcare practitioner.
What does a negative test mean?
Breath methane levels of <4 ppm are not suggestive of intestinal methanogen overgrowth.
What should I do if my test is negative? While your test is negative, this does not exclude small intestinal bacterial overgrowth as a cause of your digestive symptoms. Therefore, a follow up lactulose breath test may be useful. However, this would require a referral from a healthcare practitioner.
There is no gold standard treatment for excessive methane production. Below is a list of recommendations based on current research. However, please seek help from a qualified medical practitioner before starting any of these methods. Post treatment it may be beneficial to repeat the Methane Breath CH4ECK to see if your methane levels have reduced.
Research suggests the most effective treatment for intestinal methanogen overgrowth is a combination of antibiotics called Rifaximin and Neomycin12. However, these are not readily available on the NHS and would require the guidance of a medical practitioner familiar with this treatment.
This is a liquid diet that aims to starve the bacteria in the lower part of the digestive tract. While there are no studies in the treatment of methane production, it is effective in reducing hydrogen, which is a fuel source for the methanogens13. However, this form of treatment should only be done under the care of a trained dietitian.
Low FODMAP diet
A low FODMAP diet may alleviate symptoms in patients with IBS-C14. FODMAPs (Fermentable Oligo-, Di-, Monosaccharides and Polyols) are short-chain carbohydrates found in fibrous plant foods and calorie-free foods. These are fermented by bacteria in the gut to produce hydrogen gas, which is then used to form methane by methanogens. A low FODMAP diet may improve symptoms, but studies have shown that a low FODMAP diet did not change the number of methanogens nor reduce breath methane levels15,16.
Prebiotics and Probiotics
A recent study found that probiotic use may predispose the gut to methanogen overgrowth17. However, the probiotic strain Lactobacillus reuteri (17938) was shown to reduce symptoms of chronic constipation and reduce levels of breath methane18. This can be found in the probiotic Bio Gaia Gastros. Since overgrowth of methanogens is a form of intestinal dysbiosis, or an imbalance in the gut microbiome, then promoting beneficial bacteria with prebiotics may help to restore balance in the gut. Many prebiotic foods are considered to be high FODMAP, so it may be useful to try a prebiotic supplement, such as Bimuno.
Our research at the Functional Gut Clinic has shown a link between oral iron supplements and increased breath methane production. If you are currently taking iron supplements, or are planning to do so, then please contact firstname.lastname@example.org
The information provided is for educational purposes only and should not be interpreted as diagnostic or as treatment recommendations. Please seek advice from a healthcare practitioner, such as a gastroenterologist or dietitian, if you require further information.
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gastroenterology 112(5), 775-784 (2017). doi:10.1038/ajg.2017.46
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