Gut reactions: how understanding our microbial populations can lead to better digestive health

The gut microbe Ruminococcus gnavus lives in all of us and remains a mystery to most, but researchers at Hong Kong Baptist University have uncovered one of its secrets, and in doing so have presented hope for new ways of treating IBS

The human body is an ecosystem inhabited by trillions of microorganisms, with the vast, disparate microbial community residing in our guts exerting a huge influence on our physiological functions. The numbers alone are intimidating for any researcher looking to understand this frontier in medical science, but once we understand how certain microorganisms function inside the body, their clinical significance soon becomes apparent. 

Hoi Leong Xavier Wong, assistant professor in the School of Chinese Medicine at Hong Kong Baptist University, has made one such discovery, and it offers potential pathways to treatments for patients suffering from diarrhoea-predominant irritable bowel syndrome, IBS-D. 

“Our human gut is colonised by billions or trillions of microorganisms,” Wong says. “There are all different kinds, and these greatly contribute to the regulation of our physiological functions or the functions of different kinds of diseases. Through sequencing techniques, we can identify different kinds of bacterial species and how these can contribute to particular diseases. Through our current study in IBS, it is possible to know exactly which kind of bacteria is associated with a particular type of the disease, and we can know the mechanism by which this bacterium can contribute to the disease.”

The culprit in this instance is Ruminococcus gnavis, a gut microbe that Wong’s research has proved assumes a pathogenic role in cases of IBS-D. Ruminococcus gnavus has form. Studies have identified its role in the production of inflammatory polysaccharides in patients with Crohn’s disease. IBS-D can be added to its rap sheet. Ruminococcus gnavus can bring on the onset of the condition by breaking down dietary essential amino acids such as phenylalanine and stimulating the biosynthesis of serotonin in the gut. 

Besides the sheer numerical challenges involved, understanding the microbial communities in our gut is further complicated by the fact that they evolve over time, reacting to the changes in our body as we age. “There are dynamic changes in these kinds of bacterial species and other microorganisms during our entire lives,” Wong says. “From birth to puberty and to the end of our lives, there are dynamic changes. At different stages of our lives, these different kinds of bacteria will contribute to our physiological functions.” 

These bacteria actively react with our physiology, affecting our homeostatic balance. They influence our immune system, how we metabolise foods, our moods, and there is much to learn. “Our diet can change our gastrobiology,” Wong says. “Our activities can change these populations, and even our emotions can make changes to our gastrobiotic compositions and their functions.”

All of us are hosts to Ruminococcus gnavus but it is only in instances in which the microbe is enriched that it might cause clinical issues such as IBS-D. Wong hopes these findings will improve treatments for IBS-D, which presently only treat the symptoms of the condition. “Now that we know that it is possible for us to provide a potential cure for IBS-D by changing our diet, by changing our gut’s microbiotics,” he says.

Find out more about the School of Chinese Medicine at Hong Kong Baptist University.