A 10-year study at University College Cork — the findings are published tomorrow in the prestigious scientific journal, eLife — shows that bacteria in the gut of mice are capable of reducing abdominal pain.

This may also be the case for humans who have irritable bowel syndrome (IBS).

One in 10 people suffers from IBS, a potentially debilitating condition that is often accompanied by crippling abdominal pain.

John Cryan, one of several UCC scientists involved in the research, says he and his colleagues have conclusively shown that, in mice, gut bacteria play a key role in regulating abdominal pain.

It’s believed that this is also the case for human beings suffering from IBS.

Although the bacteria in the gut have long been thought to play a key role in pain-modulation, this study proves it, Prof Cryan said.

“IBS is one of the most common gastro-intestinal disorders seen by clinicians — it is extremely prevalent and is characterised by changed bowel habits and visceral pain,” he said. “In our research, we focused on one of the main symptoms of IBS, which is the pain.”

“We found that by targeting the bacteria in the gut, you can alleviate one of the symptoms of IBS.

“This is the first time we have conclusively shown that microbes in the gut play a critical role in abdominal pain.”

Prof Cryan, Ted Dinan, and others have been carrying out the research at the Science Foundation Ireland-funded APC Microbiome Institute at University College Cork.

However, that’s not all — the team also discovered a significant link between gut bacteria and the brain.

“We also focused on the brain to see what its impact on the pain in mice would be,” said Prof Cryan.

“Our research with the mice also showed that microbes can regulate key brain areas that sense pain. This is the first time we have actually been able to categorically demonstrate that the microbiome can affect not only the pain symptoms, but also the brain mechanisms underlying this.”

Abdominal pain, says Prof Cryan, is one of the “hardest symptoms to treat,” but he adds that these findings offer hope.

“We currently don’t have great treatment for it, so the potential here is by specifically targeting certain bacteria in the gut,” he said.

He says scientists may now be able to alleviate pain by the judicious manipulation of diet, prebiotics (substances that nourish the good bacteria in the gut), or probiotics (live bacteria in foods or pills).

The human gut is home to more than 100trn bacteria, and other micro-organisms, collectively known as the microbiota.

Gut microbiota is involved in critical processes such as digestion, metabolism, immune responses, and absorption of nutrients. Until recently, little was known about how the microbiota influences the nervous system.