Congratulations, You Have Two Brains!
You might be surprised to learn that on average, people have 10-100 times more microorganisms in their bowels than cells in their body. The total weight of the gut microbes are roughly equivalent to the weight of the human brain. What’s more interesting is the fact that these microbes play major role in how you think, feel and function throughout the day.
Physicians in the early 1900s became interested with the effect gut microbes had on the health of the individual. Doctors even started trying to influence the intestinal microbiota with the introduction of specific bacteria. Other physicians opted to simply remove portions of the colon in sick patients. In either case, the medical community has a long-held appreciation for the influence intestinal microbes have on conditions such as fatigue, gastrointestinal issues and neuroses. Current research into the gut-brain axis is giving us a better understanding as to why the intestinal microbiota can have such a profound effect on our minds and bodies. (Gut Pathogens)
THE GUT-BRAIN AXIS
The gut-brain axis is the term we give to the communication between the enteric nervous system and the central nervous system. Other names used to refer to the enteric nervous system are the “second brain” or the “gut-brain." The “gut-brain” contains over 100 million neurons - more neurons than are present in the spinal cord. The enteric nervous system and the central nervous system are in constant communication with each other, which can affect not only gastrointestinal function, but our emotions and thinking. To understand the communication, we need to talk about one of the most important nerves in your body.
VAGUS, NOT VEGAS
Your nervous system is essentially the electrical wiring for your body. Think of it as a communication network, or the body’s internal operating system. The main nerve responsible for communication between the central nervous system and enteric nervous system is the vagus nerve. The vagus nerve originates at the brainstem and is used by the central nervous system to communicate with the vocal cords, heart, lungs and the digestive tract. (Vagus) The Vagus nerve is the main highway for communication between the brain and your gut. However, the information travels in both directions, and a majority (80-90%) of the fibers are actually traveling from the gut back up to the brain. (Bidirectional) Although the brain uses the vagus nerve to control gastrointestinal function, the gut-brain is so well-developed and complex that even if the vagus nerve is severed, gastrointestinal functions will still be carried out. The vagus nerve is involved in the communication of the microbes in the gut and the brain.
BACK TO BACTERIA
There are trillions of microbes in the gut, the majority of which are bacteria. Microbiota in your gut produce 50% of your body’s dopamine and around 90% of serotonin. These are the neurotransmitters associated with feelings of well-being. There is evidence that, for their own survival, gut microbiota can even influence your eating behaviors. In studies involving germ-free animals, researchers found that the absence of gut microbiota led to neuromuscular abnormalities. In other studies, mice were shown to behave less anxiously and have higher levels of GABA when fed probiotics. (Anxiety) Researchers have shown that administering beneficial microbes can reduce inflammation and anxiety in humans (Inflammation).
While it’s clear that the gut microbiota can influence behavior and health, and that your diet can influence your gut microbiota, we still don’t fully understand how to control the system effectively. While the research into probiotic supplementation is promising, don’t rush to immediately load up on supplements without doing your research. There’s also no substitute for cleaning up your diet.