An Undeniable Connection
If you’ve ever used the expressions “gut feeling” or “butterflies in my stomach,” you may have thought you were being entirely figurative. But these phrases hint at a very real and fascinating connection between your digestive system and brain called the gut-brain axis.
Now, what is the gut-brain axis? Simply put, it’s a highly intricate two-way communication system linking your gut and brain. The main players in this arrangement are the central nervous system (CNS), the enteric nervous system (ENS) in your gut, and your gut microbiota—the trillions of microorganisms living in your digestive tract.
Two Brains
The gut and the brain are connected in a few different (and unexpected) ways:
The vagus nerve, one of the biggest nerves connecting the gut and the brain, sends signals both ways. Think of it as your gut being your second brain, with signals from it often telling your actual brain what to do. About 90% of fibers in the vagus nerve carry information from the gut to the brain. This structural feature speaks volumes about the importance of gut health for overall wellness.
Neurotransmitters, chemicals released by nerve cells to affect other cells, also connect the gut and the brain. Just as neurotransmitters produced in your brain control your emotions, gut cells release chemicals that have far-reaching effects on your body. 95% of the body’s serotonin—a neurotransmitter responsible for mood, cognition, memory, and more—is produced in the gut. Isn’t it mind-boggling to think that a chemical so crucial for your mental health is mainly produced in your gut of all places?
Besides aiding digestion, the microbes living in your gut also create chemicals that reach and affect the brain. One example is gamma-aminobutyric acid (GABA), the chemical that controls fear and anxiety. Gut microbes also produce short-chain fatty acids, which reduce appetite and brain activity related to feeling rewarded by high-calorie foods.
Lastly, the gut and the brain are connected via the immune system. Certain gut bacteria can create toxins, which cause inflammation, your body’s immune response. We know that too much inflammation is harmful to us in many ways, causing both mental health disorders and physical diseases.
Managing stress for your overall health
Now that you understand how the gut-brain axis works, you may wonder how you can support your overall health by supporting brain and gut health. One significant way is to decrease your chronic stress levels.
The gut-brain axis and the immune system are very sensitive to psychological stress. The relationship between stress and your gut is bidirectional; stress can alter the gut microbiome, and the reverse is also true, with the gut microbiome regulating stress. This relationship explains why irritable bowel syndrome is comorbid with depression and anxiety.
While your brain controls the production of cortisol (the stress hormone), cortisol receptors are present on gut cells. As a result, cortisol directly affects gut function, altering the time it takes for nutrients to pass through the gut, the integrity of the gut’s protective lining, and your body’s ability to fully absorb nutrients from food.
Leaky gut syndrome
You may have heard of leaky gut syndrome, a proposed condition in which chronic stress and other factors leading to inflammation cause the intestinal lining to erode over time, allowing normal gut bacteria to move from the inside of the intestines to the outside. There, these bacteria and their toxins can enter the bloodstream, causing inflammation and possibly contributing to diseases like IBS, celiac disease, diabetes, polycystic ovary syndrome, and mental health conditions.
Caring for your gut-brain axis
The undeniable interplay between gut and brain health may be an unpleasant realization for those who have treated the well-being of their gastrointestinal system as an afterthought. If this is you, it’s not too late to start! It’s essential to take a multifaceted, well-rounded approach to wellness, taking care of your brain and gut health while also managing your stress levels and exercising regularly.
Since the types and abundance of gut bacteria are so important to your overall health, it’s crucial to have a balanced gut microbiome. It’s always wise to eat probiotic-rich foods or to use a supplement that includes probiotics or metabiotics. These will encourage a healthier gut and, by extension, a healthier body and mind.
