Scientists highlight gut serotonin effects on IBS management

New research unpacks the complex interactions between gut bacteria and irritable bowel syndrome (IBS). Researchers at the University of Gothenburg, Sweden, reveal how gut bacteria can produce serotonin — known as the “happy hormone” neurotransmitter — which is crucial in overall digestive health and mood. 

Previous research shows that gut bacteria can affect how much serotonin is produced by the human host, but it has been unclear whether gut bacteria themselves can form the biologically active neurotransmitter.

Published in the journal Cell Reports, the paper pinpoints two bacteria that produce serotonin together — Limosilactobacillus mucosae and Ligilactobacillus ruminis.

“It is incredibly fascinating how the gut bacteria can produce bioactive signaling molecules that affect health,” says lead author Fredrik Bäckhed, professor of molecular medicine at Sahlgrenska Academy at the University of Gothenburg.

Magnus Simrén, professor of medical gastroenterology at Sahlgrenska Academy at the University of Gothenburg, adds: “Our results indicate that certain intestinal bacteria can produce bioactive serotonin and thus play an important role in intestinal health and open new avenues for the treatment of functional gastrointestinal disorders such as IBS.”

New IBS interventions

IBS is a common gastrointestinal disorder and is diagnosed more often in women, with symptoms such as abdominal pain, constipation, or diarrhea.

While the cause of the disease is not clear, research has found the intestinal environment, gut microbiota, and serotonin to be important factors.

Serotonin is a neurotransmitter found in the brain, but over 90% of the body’s serotonin is produced in the gut, where it modulates bowel movements via the enteric nervous system, often called the “gut-brain axis.”

In the study, bacteria introduced into germ-free, serotonin-deficient mice boosted gut serotonin levels, as well as the density of nerve cells in the colon. The bacteria also normalized the intestinal transit time.

The researchers noted that people with IBS had lower levels of one of the bacteria (L. mucosae) in their stool compared to healthy individuals, and that this bacterium also has the enzyme required for serotonin production.

“Our findings indicate that intestinal bacteria can form signaling substances such as serotonin, which may be the key to understanding how the intestine and its inhabitants can affect our brain and behavior,” concludes Fredrik Bäckhed.

Expanding research on gut axes

In other research exploring gut health’s ties with overall well-being, BiOkuris recently spotlighted research supporting that its synbiotic BK002 offers benefits for gastrointestinal symptoms and significantly reduces anxiety. Nutrition Insight connected with the company to learn why synbiotics are considered superior among dietary interventions for IBS treatment.

Meanwhile, a study in July supported dsm-firmenich’s synbiotic-butyrate supplement claims for relieving IBS symptoms. The formula blends microencapsulated sodium butyrate, probiotics, and short-chain fructooligosaccharides.

IBS was also recently named the culprit in people’s perceived symptoms of gluten allergies, according to another paper. The researchers found that subjects with reported gluten intolerance experienced worse symptoms, even when fed a gluten-free placebo.