Researchers in the blossoming field of neurogastroenterology are finding that our “second brain” — the enteric nervous system — does much more than handle digestion; it partly determines our mental state and plays key roles in certain diseases throughout the body.

Some surprising facts:

• The enteric nervous system contains some 100 million neurons, more than in either the spinal cord or the peripheral nervous system.
• A big part of our emotions are probably influenced by the nerves in our gut (“gut feeling”).
• The enteric nervous system uses more than 30 neurotransmitters, just like the brain, and in fact 95 percent of the body’s serotonin is found in the bowels. Antidepressant medications called selective serotonin reuptake inhibitors (SSRIs) increase serotonin levels, so meds meant to cause chemical changes in the mind often provoke GI issues as a side effect.
• There may be connections between diseases and lesions in the gut’s nervous system.