Gut Inflammation & Serotonin

By Rebecca | Maternity Nurse and Gut Health Advocate

Gut inflammation doesn’t just affect digestion—it can also influence key chemical signals in the body, including serotonin.

Around 90% of serotonin is produced in the gut, where it plays an important role in regulating digestion, gut motility, and communication along the gut–brain axis. The production of serotonin is closely linked to the balance of bacteria in the microbiome.

When the gut becomes inflamed, this balance is disrupted. As a result, serotonin production and signalling can be affected, which may:

• Alter gut motility (leading to diarrhoea or constipation)

• Increase gut sensitivity and discomfort

• Impact mood, stress response, and sleep

• Contribute to ongoing digestive issues
  

Emerging clinical research supports this connection. For example, a recent randomised, placebo-controlled trial found that modulating the gut microbiome with probiotics improved gastrointestinal symptoms and influenced pathways linked to the gut–brain axis, including serotonin-related activity.

Additionally, research shows that gut bacteria play a direct role in regulating serotonin metabolism and production, highlighting how closely gut health and neurotransmitter balance are linked.

This highlights a powerful cycle: gut inflammation disrupts serotonin balance, and altered serotonin can further affect both digestive function and overall wellbeing.

Supporting the gut, reducing inflammation, and restoring microbial balance may therefore be key not only for digestive health, but also for mood and long-term health.