You probably already know that our guts and brains are intricately connected, but researchers clearly understand that our guts have functions well beyond digestion. In fact, there is such an extensive network of neurons lining our guts that some scientists have coined the gut our “second brain,” and it can partially determine our mental state and overall health.
That’s not to say that the gut is capable of conscious thinking. It’s not. Then what is our “second brain”. . . really? Michael Gershon, chairman of the Department of Anatomy and Cell Biology at New York-Presbyterian Hospital/Columbia University Medical Center, is an expert in neurogastroenterology and sheds some light on this.
Our second brain is technically known as the enteric nervous system, and it is made up of sheaths of neurons embedded in the walls of the long tube of our gut, the alimentary canal. It contains an astounding 100 million neurons, which is more than the spinal cord or the peripheral nervous system, says Gershon.
Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles, adds, “The system is way too complicated only to make sure things move out of your colon.” In fact, scientists were amazed to learn that about 90 percent of the fibers in the primary visceral nerve, the vagus nerve, carry information from the gut to the brain and not the other way around. “A big part of our emotions are probably influenced by the nerves in our gut,” adds Mayer.
In fact, everyday emotional well-being may rely on the messages our guts send to our brains.
Mayer is, incidentally, working on how the trillions of bacteria in the gut “communicate” with enteric nervous system cells. His professional observations concerning the gut’s nervous system has led him to believe that psychiatry will need to expand its parameters to include the function and role of the “second brain” in the coming years.
Adding to the gut-brain connection is that 95 percent of the body’s serotonin—the “feel good” neurotransmitter—is in the gut and plays a large role in mood and emotions. Leakage of serotonin from the gut can be problematic and may even play a role in autism, says Gershon. He discovered that the same genes in synapse formation between neurons in the brain are involved in the gut synapse formation. “If these genes are affected in autism,” he says, “it could explain why so many kids with autism have GI motor abnormalities” in addition to elevated levels of gut-produced serotonin in their blood.
That’s not all, though, concerning gut-brain connections and health.
Current research is focused on how the “second brain” is involved in bone health as well as how it mediates the body’s immune response, since at least 70 percent of our immune system is in the gut.
That’s a lot of gut-brain connections to health, huh?