Farts are causing a stink in the research world - but in a positive way.
Melbourne scientists have revealed how hydrogen is made and used in the human gut. Though infamous for making farts ignite, hydrogen also has a positive role supporting gut health.
In this study published in Nature Microbiology, researchers from Hudson Institute of Medical Research and Monash University led an international team that analysed how microbes control hydrogen levels in the gut.
Hydrogen gas is naturally produced in the gut when bacteria ferment undigested carbohydrates from our diets. Some of this gas is exhaled, much is recycled by other gut bacteria, and the rest exits the body as flatulence.
First author Dr Caitlin Welsh, who was co-hosted by Hudson Institute and Monash University, said gut microbes can generate up to a litre of hydrogen gas per day, and these results revealed hydrogen has an even bigger role in gut function than previously thought.
"Most people release about a litre of gas per day and half of that is hydrogen. But hydrogen is more than just the gas behind flatulence - it's a hidden driver of gut health," Dr Welsh said. "Our study shows hydrogen shapes the gut microbiome in surprising and varied ways. It helps some beneficial bacteria thrive in the gut and keeps digestion going."
The researchers hope their discovery will highlight the need to expand fundamental knowledge of how our gut works so it can be used to design new treatments for gastrointestinal issues.
Dr Welsh, who is now a postdoctoral scientist at Hudson Institute, said the results suggest that some bacteria which can switch between different energy sources might be more important in using hydrogen than previously thought.
"Overall, this research gives new insight into how hydrogen is made and used in the gut and how it affects health," Dr Welsh said. "Hydrogen is key to many biological processes but until this study the ways it contributes to gut microbiome community diversity and interactions were poorly understood.
"This study demonstrates that hydrogen is a key player in determining gut microbiome structure and health, however the precise mechanisms and links to health and disease remain to be understood. This study highlights a need for further research to understand their role in disease."
Co-senior author Associate Professor Sam Forster said these newly discovered links could increase understanding of gut conditions and guide development of new microbiome based treatments.
A/Prof Forster said while emerging microbiome based therapies range from faecal transplants and probiotics to live biotherapeutics, we have a long way to go to fully understand how they work and how best to use them.
"By understanding the functions of these systems, it opens up new opportunities for therapeutic interventions, some of which we haven't even considered."
Co-senior author Professor Chris Greening, who leads the One Health Microbiology group at Monash University's BDI, said hydrogen is a common but poorly understood substance in the human gut.
"Gas production in the gut is a normal process. It's made in large amounts when gut bacteria break down food and is then used by other microbes for energy," Professor Greening said.
However, excessive hydrogen production can signal gut problems. Abnormal hydrogen levels are associated with infections, digestive disorders, and even cancer, and are often measured in breath tests to assess gut health.
"We also saw signs that hydrogen production was disrupted in people with gut disorders, but it's unclear if this is a cause or consequence of disease," Professor Greening said.
The researchers' work was focused on understanding the fundamental role of hydrogen in gut function, rather than improving diagnostics or developing therapies.
What the research discovered
The study found that a specific enzyme called Group B [FeFe]-hydrogenase was mainly responsible for making hydrogen in the gut. This enzyme is found in many gut bacteria and is very active. The researchers studied bacteria from stool samples and gut tissue and found that this enzyme helps bacteria grow and produce hydrogen, especially in the primary health associated groups. They also discovered that this enzyme works by using a specific chemical reaction involving iron and another protein called ferredoxin. As an example, healthy people have a lot of these enzymes in their gut, but people with Crohn's disease have fewer of them and more of other types of hydrogen-producing enzymes.
