In 2022, Caltech researchers discovered that a specific microbial metabolite called 4-ethylphenyl sulfate can increase anxiety in mice. They also found that transferring fecal microbiota from anxious mice to non-anxious mice caused the latter to become anxious. In addition, antibiotic treatment in mice, which affects the gut microbiome, has been shown to impact anxiety levels.
The gut-brain axis is a communication pathway that connects the brain and the gut. The brain sends signals to the gut through the vagus nerve, and the gut communicates back to the brain. This communication is influenced by hormones, neurotransmitters, and cytokines. Neurotransmitters are molecules that facilitate communication between brain cells. Interestingly, neurons also exist in the gut. The gut microbiome has an effect on certain neurotransmitters, including serotonin, which plays a significant role in mood regulation. It is worth noting that 95% of the body’s serotonin is produced in the gut by neurons located in the GI tract, as well as by immune cells and enterochromaffin cells. Gut serotonin can activate nerve endings in the digestive tract, which in turn impacts the central nervous system.
