How the Gut Microbiome Influences IBS

What is the gut microbiome?   

The word “microbiome” means a community of microbes (and genetic material) living in a particular environment, like your body.   

Most of the microbes that live in your body are in the gut, especially the large intestine. The phrase ‘gut microbiome’ means all the microbes living in the gut.  

Microbes include bacteria, yeast and fungi. But bacteria which make up about 99% of the microbes in your gut. They’re also the ones we know the most about.

What do microbes do?  

We provide microbes with a place to live, and in turn they help to keep us healthy. Some of the jobs your gut microbes carry out include:   

• Breaking down and extracting energy from fibre   
• Producing compounds which help keep the lining of the gut healthy   
• Supporting immune function, stopping harmful microbes from multiplying   
• Regulating mood and behaviour, by producing chemicals which send signals to your brain   

Researchers are still figuring out what a "healthy" microbiome looks like. It’s generally agreed that a diverse microbiome is important. This means having many different species of bacteria.   

Because gut microbes impact our health, scientists want to understand what happens when there is a change in the make-up of the microbiome.  

So, what's the connection to IBS?   

Some studies have found that the gut microbiome in people with IBS is different to people without IBS. For example, some people with IBS have lower levels of some types of beneficial bacteria. It’s not clear if this is a cause or consequence of IBS.   

But there’s also evidence that changes in the gut microbiome might play a role in how IBS develops.   

The findings have sparked interest in microbiome-based therapies. These therapies include prebiotics and probiotics. They might work by replacing missing strains or outnumbering harmful strains.  

So, what do we know so far? In the next two lessons, we’ll look at the evidence for each of these in turn.