When it comes to your mental health, your behavior, and even your mood, we tend to think that the brain is in charge. In reality, your gut may be calling the shots. In the 1800s and early 1900s, it was thought that wastes in your colon could produce infections that lead to depression and psychosis.
Widely accepted for a time, mental-health patients were often treated with colonic purges and bowel surgeries, but eventually this was regarded as quackery.
“Scientists are increasingly convinced that the vast assemblage of microfauna in our intestines may have a major impact on our state of mind.”
Your Gut Is Intricately Connected to Your Brain
In addition to the brain in your head, embedded in the wall of your gut is your enteric nervous system (ENS), which works both independently of and in conjunction with the brain in your head.
Your ENS contains 500 million neurons and is thought to be largely responsible for your “gut instincts,” responding to environmental threats and sending information to your brain that affects your well-being.
This communication between your “two brains” runs both ways and is the pathway for how foods affect your mood.
For example, fatty foods make you feel good because fatty acids are detected by cell receptors in the lining of your gut, which then send warm and fuzzy nerve signals to your brain.
However, this gut-brain connection is far more than just comfort food or butterflies in your stomach. According to Scientific American:2
“The gut-brain axis seems to be bidirectional—the brain acts on gastrointestinal and immune functions that help to shape the gut’s microbial makeup, and gut microbes make neuroactive compounds, including neurotransmitters and metabolites that also act on the brain.
These interactions could occur in various ways: microbial compounds communicate via the vagus nerve, which connects the brain and the digestive tract, and microbially derived metabolites interact with the immune system, which maintains its own communication with the brain.”