Author: Christine Stewart

April 2021

 

Is your patient a methane producer and what does it mean for their health?

Methane is an odourless gas produced by Archeal species which can also be called methanogens. Just like bacteria, archaea are single-celled organisms, but in other ways they are so different that they are classified in an entirely different domain of life than bacteria or eukaryotes (multi-cell organisms such as parasites or fungi).

Not all human microbiomes contain methanogens. In fact, only around a third (33%) of the world’s population are estimated to be methane producers¹. Interestingly, Microba’s own database revealed approximately 32% of research participants (typically Australian) were shown to be methane producers.

Formation of Methane by gut microbes

 

Methanogens present in the gut play an important role in converting hydrogen into methane (see Fig 1.). Hydrogen is produced when bacteria convert fibre into beneficial short chain fatty acids (SCFAs). If the levels of hydrogen build-up, this has an inhibitory effect on bacterial metabolism. The consumption of hydrogen by methanogens helps ensure the continued production of beneficial SCFAs.

There is no need to worry if methanogens are not present, as hydrogen can also be consumed by hydrogen sulphide producing bacteria and some acetate producing bacteria. In fact, the balance between these hydrogen consuming microbes is determined by factors such as the availability of hydrogen, sulphur, oxygen and gut pH within the gut.

Methanogen species

The most commonly detected methanogen, Methanobrevibacter_A_smithii utilises hydrogen (H2) and carbon dioxide (CO2) to produce methane (CH4)². It is well known that this species contains high levels of strain diversity with our database already able to distinguish Methanobrevibacter_A_smithii found in 24% of Insight™ samples with the closely related Methanobrevibacter_A_smithii A which is found in 4% of samples. Lesser-known methanogens include Methanosphaera stadtmanae and Methanomassiliicoccales_A intestinalis which are found in 6% and 1% of Insight™ samples.

Potential role of methanogens in the GI tract

Methanogenesis may be helpful in reducing the volume of gas within the intestine as the methane produced by Methanobrevibacter_A_smithii species takes up much less space than its parent molecules, hydrogen and carbon dioxide³. This could be good news for patients who may be experiencing bloating or symptoms of visceral sensitivity such as pain – commonly reported in irritable bowel syndrome (IBS).

However, perhaps it’s a balance in methane production that may be optimal for certain subtypes of IBS? Patients diagnosed with constipation-dominant IBS (IBS-C) have been shown to have increased methanogen prevalence in the gut, whereas patients diagnosed with diarrhoea-dominant IBS were shown to have reduced prevalence¹. The effects of methane on gut transit time may provide some indication as to why research has shown differences in methanogen prevalence in the subtypes of IBS.

 

Methane is a gastrotransmitter, meaning it can act on the cholinergic pathway of the enteric nervous system (ENS)⁴. When methane interacts with the ENS it increases the contractility of the gut whilst simultaneously reducing peristalsis-movement along the gut⁴ (see Fig. 2). This suggests that high levels of methane production could be one of the mechanisms for the increased gut transit seen in constipation, IBS-C, IBD and diverticulosis^1,4.

Benefits of methane for metabolic health

Methanogenesis can also have a positive effect on the gut microbiome. As already discussed, methanogens play an important role in regulating hydrogen levels in the gut resulting in increased efficiency of SCFA production by gut bacteria¹. SCFAs benefit human health through their anti-inflammatory effects and positive influence on maintaining gut barrier integrity.

Additionally, there is emerging evidence that members of the rare Methanomassiliicoccales order could play an important role in metabolic health by reducing trimethylamine (TMA) levels through the conversion of TMA into methane¹.

 

Early research reported elevated methanogens in obese versus lean people. However, these results have not been consistently replicated². Emerging research is now revealing that methane may play a beneficial role in metabolic health by stimulating glucagon-like peptide -1 (GLP-1) secretion⁵. GLP-1 is a hormone produced by L cells in the distal ileum and colon which helps control glucose levels by stimulating glucose-dependent insulin production. The beneficial impact of methane on metabolic health is further confirmed by studies that have reported reduced methanogenesis to be associated with insulin resistance^6,7 and visceral adiposity⁸.

What can practitioners do?

While methane production can make a valuable contribution to health by allowing more efficient SCFA production and stimulation of GLP-1 release, excessive levels of methane can be a mechanism for the increased gut transit time seen in constipation, IBS-C, IBD, and diverticulosis.

So what can be recommended to patients? Fibre plays an important role in regulating gut transit time which may be important for those with an elevated potential to produce methane. However, the role of different types of fibre is still emerging. For example, an in-vitro study using human faeces demonstrated that inulin, a type of prebiotic fibre found in asparagus, artichokes, onions and leeks was shown to increase the production of methane compared to partially hydrolysed guar gum (PHGG) and wheat dextrin⁹. Additionally, a human dietary intervention study showed that beta-glucan, found in oats and barley, increased breath hydrogen without impacting methane levels¹⁰.

In conclusion:

• Methane production can support SCFA production and GLP-1 release.
• Excessive levels of methane production can be a mechanism for the increased gut transit time seen in constipation, IBS-C, IBD and diverticulosis.
• Different types of fibre may play an important role in regulating gut transit time in those with an elevated potential to produce methane.

Insight™ gut microbiome analysis can help identify whether your patient is a methane producer, along with their microbiome’s fibre digestion potential. Contact your Clinical Application Specialist to discuss optimising Insight™ gut microbiome analysis in your clinical practice.