Gut health: your mysterious second brain

The second brain may influence your immune system response.

Your ability to resist disease may come from your second brain.

The bacteria in your gut may affect mental health.

If you’ve ever made a “gut decision” or felt “butterflies in your stomach,” you were probably getting information from an unexpected source: your second brain.

What is your second brain?

Something remarkable is happening in your gut every day, and it’s affecting how you feel physically, mentally and emotionally. The enteric nervous system is a mass of neural tissue located in the lining of the gastrointestinal system. It begins in the lower part of the esophagus and travels all the way into the rectum. Along its path there are millions of neurotransmitters that play a role in influencing your mood — and possibly much more.

In addition to helping with digestion and giving you nervous butterflies on occasion, the enteric nervous system communicates directly with your first brain — the one in your head. Doctors are beginning to understand the second brain’s important role in digestion, mood and health.

Interestingly — and this is something many people don’t realize — in addition to controlling digestion, the second brain can affect feelings of sadness or stress, as well as influence memory, learning and decision-making. There is still a long way to go in medical research to completely understand the reach and influence our second brain has over things like major depression, autism, heart disease, colon cancer, multiple sclerosis, obesity and certain autoimmune diseases, but more and more evidence suggests the second brain, and the microbes in our gut, are intimately connected to all of it.

How does the second brain work?

The vagus nerve is the longest cranial nerve that links the brain stem to the heart, lungs and gut. It acts as an information superhighway from the gut to the brain and affects your perception of hunger, fullness, stress or anxiety. Surprisingly, between 80 and 90 percent of the fibers in the primary vagus nerve carry information from the gut to the brain — instead of the other way around. However, and what is perhaps most interesting about the second brain, even if the vagus nerve were to become inoperative, the second brain is equipped with its own reflexes and senses so it has the ability to control gut behavior independently of the brain.

The second brain is responsible for breaking down food, absorbing nutrients and expelling waste, but researchers have noted it is too complicated for digestion to be its sole purpose.

How does the second brain affect mood and mental state?

If you’ve ever experienced tummy troubles, then you know how it can affect your mood. Everyday emotional well-being may rely on your first brain receiving messages from the second brain in your gut. In fact, 95 percent of the body’s serotonin, a chemical responsible for regulating mood and behavior, is found in the bowels. A drop in serotonin is a known factor in those suffering from depression. Moreover, it is well known that tummy troubles often come with feelings of anxiety, stress and depression. Scientists are beginning to examine irritation in the gastrointestinal system as a trigger for mood changes.

How does the second brain affect health?

Recently, you may have heard about the gut microbiome; a bacterium that exists as part of the enteric nervous system. Gut microbes have quickly become one of the most intriguing areas of biomedical research, with a particular focus on how the second brain educates our immune system and helps us resist disease.

Research suggests that some gut microbes are at least partially responsible for certain diseases such as Parkinson’s and mental health conditions like dementia. The likely reason stems from the chemicals they produce, which influence brain structure, function and development.

As a result of these discoveries, gut microbes are now being marketed as the way forward for personalized medicine and discovering the solution to all of our health problems. However, scientists have only just begun to research gut microbes and how they affect the human body.

There is still a long way to go to determine exactly how the second brain influences brain function and immune system response. However, eating well, staying hydrated and getting plenty of rest and exercise will help lower your risk of many health conditions and diseases. In the meantime, learn how you can stay healthy or improve your health by making a few easy healthy lifestyle changes, and try these five foods that can improve your gut health.

This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.