Where is your second brain? The story goes that a man’s second brain is in his pants and a woman’s is in her heart, but what if I told you it was in your stomach? Within each of us exists a huge network of nerves lining our GI (gastrointestinal) Tracts, from esophagus to anus. With over 100 million neurons and 30 neurotransmitters, it is clear that the enteric nervous system (ENS) is a complex network that has evolved to serve multiple functions. Not only does this tract make for effective digestion, it also impacts our emotions, particularly our anxiety levels.

The ENS is said to have more neurons than or spinal cords or even peripheral nervous system. Scientists and GI specialists have theorized that the complex network was initially developed to help for smoother digestion. We are able to gauge how hungry, unsatisfied, satiated or sick we are through the nerves in our stomach. This system likely evolved as a way of allowing our brains to bypass something as automatic as digestion and allow more energy for cognition and higher level processing. Our stomachs communicate with our brains through the vagus nerve, and our brains tell us, “Stop eating that!” or, “RAWR! You’re hungry!”

GI Doctors and Psychologists believe that this network is too complicated to be limited to such an explanation. While these basic necessities and forms of communication are indeed essential to our digestion, the intricate network of nerves and hormones exceeds the what is necessary for proper bowel movements. Specialists have concluded that the ENS tells the brain about more than just food.

The American Psychological Association released a study showing that bacteria levels in the stomach are linked to anxiety. The ENS gauges these bacteria levels in our stomachs and releases one or more of over 30 neurotransmitters, which can also be found in the brain. The Scientific American reported that an estimated 95% of our serotonin can be found in our GI tract. Do you get butterflies when you’re nervous? In a study done by Bienenstock and colleagues, mice who were given a regimen of probiotics showed lower levels of stress and higher levels of GABA (a calming neurotransmitter) during a maze. They were also more likely to persevere and less likely to, “give up and just start floating” when given a swim test.

So what does this tell us, college students about diet, stomach health, and stress? Take care of the former and you’ll inevitably improve the latter. Eating right and taking probiotics can chemically reduce anxiety and elevate mood. It is not uncommon to experience stress in your stomach, but you can preemptively combat this by maintaining a (semi) healthy diet (we’re in college) and taking daily probiotics. It can be easy not to prioritize healthy eating when having to feed yourself for the first time (freshman 15, anyone?), but this may come back to bite you, in more than just your pants size. A happy second brain leads the way to a happy first brain.