University Study Discovers New Effective Clinical Target to Manage Irritable Bowel Syndrome

The research team of Professor Bian Zhaoxiang, Director of the Clinical Division and Tsang Shiu Tim Endowed Professor in Chinese Medicine Clinical Studies (C); Dr Xavier Wong Hoi-leong, Assistant Professor of the Teaching and Research Division (R); and Dr Zhai Lixiang, Post-Doctoral Research Fellow (L) of School of Chinese Medicine at Hong Kong Baptist University, in Hong Kong, on Jan. 4, 2023 Courtesy of HKBU

Researchers at the School of Traditional Chinese Medicine of Hong Kong Baptist University discovered that an intestinal bacteria called ruminococcus gnavus is the primary culprit that triggers diarrhea-predominant irritable bowel syndrome, and they have found a new remedial target for the disease.

Bian Zhaoxiang, Director of the Clinical Division and Tsang Shiu Tim, Endowed Professor in Chinese Medicine Clinical Studies; Dr. Xavier Wong Hoi-leong, Assistant Professor of the Teaching and Research Division; and Dr. Zhai Lixiang, Post-Doctoral Research Fellow of SCM at HKBU, joined hand in the groundbreaking study.

The university study also found that consuming foods with low protein, such as fresh fruits, vegetables, and bread, may help reduce the gastrointestinal motility of diarrhea-predominant irritable bowel syndrome (IBS-D).

What Is Diarrhea-predominant Irritable Bowel Syndrome

Diarrhea-predominant irritable bowel syndrome (IBS) is a common functional gut disorder distinguished by irregular bowel movements, abdominal discomfort, and bloating.

HKBU estimates that about seven percent of adults in Hong Kong are affected by IBS.

Diarrhea-predominant irritable bowel syndrome (IBS-D) is the most common type, and there is no known cure for the disease. Hence, most clinical treatment focuses on relieving symptoms.

The medical research team found a large amount of phenethylamine and tryptamine in the fecal samples collected from 290 patients with diarrhea-predominant irritable bowel syndrome

What the Researchers Uncovered

Phenethylamine and tryptamine stimulate serotonin production from enterochromaffin cells in the intestines by activating TAAR1, a trace amine-associated receptor. TAAR1 triggers gut motility and secretion disorders in IBS-D.

The research proved that using specific inhibitors to prevent TAAR1 activation can effectively reduce the symptoms of diarrhea.

What Is Serotonin

According to the professors at HKBU, serotonin is an essential neurotransmitter for regulating gut motility, contributing to the gastrointestinal symptoms exhibited in IBS-D patients.

Bian said, “Patients with IBS-D often suffer from diarrhea and abdominal pain, which diminish the quality of life.”

He added that the inhibition pathway in the findings brings hope for a new therapeutic development to treat diarrhea irritable bowel syndrome.

An experiment showed that a diet with low phenylalanine, an amino acid, could reduce tryptamine and its production. It suppressed the microorganisms and inhibited intestinal peristalsis in mice.

Foods with low protein content include fresh fruits, vegetables, and bread, which are relatively low in phenylalanine.

Wong added that reducing the intake of high-protein food with high levels of phenylalanine, such as red meat, may also help patients manage diarrhea-predominant irritable bowel syndrome.

The research findings by the Hong Kong professors have been published in the international scientific journal Cell Host & Microbe.