The 'Second Brain' in Our Bellies and How it Controls Digestion

A team of Duke University researchers are hopeful a study on the digestive tract of lab mice will provide new insights into how the nervous system and the stomach work in conjunction within humans. Jakob Helbig/Gallery Stock

This article originally appeared on Medical Daily.

We are all familiar with the brain, the organ that controls every function, thought, and reflex in our bodies, but an increasingly large group of researchers have begun to suggest we may have a "second brain."

The team at ASAP Science in a recent video explain how a group of nerves, known as the enteric nervous system, is located in our gut and controls far more than you might realize.

What makes the enteric nervous system so special is that it controls the entire digestive system, from the esophagus to the anus, and is able to function completely on its own even when completely cut off from the brain. In addition to controlling our digestive system, the enteric nervous system also has a surprising effect on our mood and behavior. Around half of all our dopamine and 90 percent of our serotonin, two hormones associated with good feelings, are produced by bacteria in our gut. In addition, these gut bacteria can also send messages directly to the brain requesting certain types of foods.

"The system is way too complicated to have evolved only to make sure things move out of your colon," Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles (U.C.L.A.) told Scientific American. Instead, ASAP Science suggests, we developed the enteric nervous system as a way to have a direct line of communication between the brain and gut during our evolution, because what we eat has such a big effect on our survival.

These gut bacteria not only control appetite, they also have an effect on our mood. According to ASAP Science, in some studies, eating yogurt filled with healthy bacteria produced a measurable decrease in individuals' depression and anxiety. In addition, healthy gut bacteria also result in a higher resilience from negative emotions, a trait that makes you more forgiving and social.