Your gut contains some 100 million neurons, more than in either the spinal cord or the peripheral nervous system. This is called the ‘the enteric nervous system (ENS), popularly referred to as the ‘second brain’. Just like the brain, the enteric nervous system uses more than 30 neurotransmitters. In fact 95 percent of the body’s serotonin is found in the bowels. About 90 percent of the fibers in just one of the main nerves, the vagus nerve, carry information from the gut to the brain and not the other way around. Bacteria in the gut also secrete brain hormones (50% of the body’s dopamine).

The blossoming field of neurogastroenterology studies the role of the ENS. We know the neurons of the ENS can control gut behavior independently of the brain. Recent studies are finding these neurons send information to the brain that changes mood and emotions in some gut disorders which affect millions of Americans—e.g. irritable bowel syndrome. Cutting-edge research is investigating how the second brain mediates the body’s immune response; “this may explain why a higher-than-normal percentage of people with some bowel problems develop depression and anxiety.”

Those nerves in your gut are definitely designed to send information to your brain about what you are eating. We don’t know the details yet but listen to your gut; a basic healthy diet is really important. Recently there have been very interesting studies on how changing the bacterial population in the gut changes mental and physical health. If you’ve ever felt tired, nauseous, or a little “fuzzy,” after a meal, your ENS may be reacting to something you ate—and sending signals to your brain.

What can you do?

• Eat a diet rich in plants—vegetables, fruits and complex carbohydrates.
• Eat mostly healthy fats, olive, avocado and fish oils.
• Keep added sugar consumption low.
• Pay attention to medications—Medicines intended to affect brain hormones will affect those in the gut as well. This can be a good thing but can also cause ‘strange’ side affects if the connection is not on your radar.
• Probiotics can be helpful, but which ones and how much is unknown—we’re in the early days of figuring out which bacteria or which combination of bacteria are helpful for which conditions.
• Fermented foods seem to be a helpful part of your diet (yogurt, beer, kimchi, sauerkraut etc)