We use many words to describe these sensations: butterflies before a tough challenge, a pit in the stomach or gut wrenching when we get bad news, a gut check when we are faced with a grueling decision, or a gut feeling when we know deep down what to do about something we’ve been ambivalent about.
And although all these expressions have the mighty gut in common, if our emotions reside in our brain as traditionally thought, why do we often feel them deep within our stomach?
The answer lies in exciting new research showing that the brain and the gut are inexorably connected. Indeed, we are learning that our “gut” instincts can give us powerful insights into the states of both our gut and our mind.
It’s Not All In Your Head...Meet Your Second Brain
Scientists used to think that the digestive tract was solely responsible for the mechanics of digestion—chew, swallow, digest, excrete, repeat. But, an exciting new frontier in science is finding that the gut is far too complicated to only serve that one straightforward (albeit very important) purpose.
You see, your gut is lined with around 500 million neurons (that’s nearly five times more than in your spinal cord!) that make up the enteric nervous system, also called your “second brain.” And it appears that this brain in your gut can communicate with and send signals to your other brain, helping to regulate everything from your appetite and immune function to your emotional state.
How does this work? Well, it turns out that the vagus nerve—which runs from the brainstem all the way into the abdomen—acts as a sort of intercom system that delivers messages back and forth from the gut to the brain. And, we’re learning that the gut may be the chatty one in the conversation; 90% of the fibers in the vagus nerve carry information from the gut upwards to the brain, rather than the other way around.
This “gut-brain axis” serves as a communication system whereby your gut and brain are in constant contact. But, how exactly does your gut send signals up to your brain, and what does it say? This is where your body’s thriving communities of beneficial bacteria come in.
Your Microbial Brain
Your gut is home to 100 trillion microbes, most of which are beneficial bacteria called probiotics that work diligently on your behalf to support nearly every aspect of your health, from your metabolism and blood sugar balance to your cognitive function and immunity.
But your friendly flora also regulate or produce many of the 30 neurotransmitters that the enteric nervous system uses on a daily basis to communicate with your brain.1 Here are a few of the mood-enhancing chemicals that depend on your gut bugs for optimal performance:
• Serotonin. Nearly 95% of your body’s serotonin—the “happy” chemical that affects everything from your mood and appetite to your sleep and memory—is manufactured in the gut by bacteria.2
• Dopamine. Beneficial bacteria also produce dopamine (50% of which originates in the intestine), which serves as a chemical messenger in the gut and plays a big role in the brain’s reward system.
• GABA. Also known as the “calming” chemical, GABA helps to calm irritability, nervousness, and anxiety and is manufactured by gut probiotics.3
• Cortisol. Friendly flora can reduce levels of cortisol, the hormone that becomes elevated in times of stress.2
• Oxytocin. Probiotics work to boost levels of the hormone oxytocin, which increases feelings of love and bonding.4
By manufacturing and monitoring levels of these brain chemicals, producing short-chain fatty acids, and by communicating with your body’s own cells, probiotics in your gut have a big influence on your mood, cognition, and emotional state, all of which contribute to your glorious gut instincts.
What Can Your Gut Tell You?
As the only group of organs that can function without input from the brain in your head, it’s clear that your gut can call its own shots, and it wants you to pay attention!
It’s true that the initial stimulus that sparks a gut feeling (like a phone call in the middle of the night) can begin its cascade as a thought in your mind (“is my teenager okay?”), but your gut responds nearly instantaneously, like a primitive warning system alerting you that something is amiss.
Before you can even process the thoughts running through your brain, your gut knows enough to start preparing your body for “fight or flight” so you can respond right away. In this case, butterflies in your stomach at that first ring of the phone can indicate blood being ushered away from your digestive tract to your extremities so you can take immediate action.
You see, even when your thoughts are responsible for triggering your gut reactions, you often feel the effects in your gut first, which can be an important signal (as long as you pay attention to it!) that it’s time to check in with your brain to see what’s going on...and figure out how to respond. It’s the same with chronic stress—digestive discomfort and an uneasiness in your gut may be the first bodily symptoms telling you to slow down and find your center.
But sometimes your gut really is the first responder. For example, an irritated digestive tract afflicted with occasional gas, bloating, irregularity, or diarrhea can trigger feelings of temporary depression and anxiety. The good news is that supplying the gut with what it needs to heal—often a balanced microbiome—can alleviate both the physical and emotional symptoms.5
And what about food? In times of stress, your gut can initiate production of ghrelin, a hormone that sends hunger signals to your brain, prompting you to eat certain foods that will calm and satiate you (comfort food, anyone?). In one study, volunteers agreed to receive either saline or fatty acids via a feeding tube while listening to sad music and viewing sad pictures. Within minutes, the brain scans of the group receiving the fatty acids showed activated sections of the brain that moderate emotions, proving that your gut really can change your mood.6
No matter how you look at it, your gut not only influences your emotional state, but it serves as a barometer of sorts for what’s going on in your head. So, how you can make sure you listen to and trust your valuable gut instincts?
How to Trust Your Gut Instincts
A trustworthy gut—one that you can count on to both nurture and advise you—begins with a healthy gut. Remember how your masses of good guy bacteria work so hard to produce chemicals that regulate your mood and communicate with your brain?
Well, that can only happen if you have enough beneficial bacteria (around 85% in a balanced microbiome) to do the job—and in this day and age, that’s not always an easy feat. So many things can deplete your populations of beneficial bacteria, from antibacterial cleaners and antibiotics in food and as medicine to overzealous hygiene habits, indoor lifestyles, and stress.
We know that the key to a healthy gut is a thriving population of friendly flora, so follow these three simple steps to create and maintain a gut that you can trust:
1. Build. To replenish your ecosystem of good bacteria, take a high-quality daily probiotic supplement like PRO-15 that delivers billions of live bacteria deep into your gut.
2 Feed. Nourish your gut bacteria with a prebiotic supplement like prebiotic powder, a perfect mix of organic prebiotic fibers that promote the growth of your healthy bacteria.
3. Maintain. Live a gut-healthy life that focuses on ways to build your microbiome (stay active, get dirty, eat well, and relax!) and steers clear of anything that can deplete your precious microbes.
As humans, we evolved as hunters and gatherers to have a highly intuitive, interconnected system that could warn us in times of danger and keep us safe from the many lurking threats. And although our lifestyles have changed significantly since then, our nervous systems haven’t—we still have the capacity to tune into that primitive intuition.
Focusing on cultivating a healthy gut and listening to and trusting your gut instincts can enable you to dial into your innermost thoughts and feelings, so you can live your healthiest days with purpose and joy.
1. Jonge, W. J. (2013). The Gut’s Little Brain in Control of Intestinal Immunity. ISRN Gastroenterology,2013, 1-17. doi:10.1155/2013/630159
2. Kato-Kataoka, A., Nishida, K., Takada, M., Kawai, M., Kikuchi-Hayakawa, H., Suda, K., . . . Rokutan, K. (2016). Fermented milk containing Lactobacillus casei strain Shirota preserves the diversity of the gut microbiota and relieves abdominal dysfunction in healthy medical students exposed to academic stress. Applied and Environmental Microbiology, 82(12), 3649-3658. doi:10.1128/aem.04134-15
3. Bravo, J. A., Forsythe, P., Chew, M. V., Escaravage, E., Savignac, H. M., Dinan, T. G., . . . Cryan, J. F. (2011). Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proceedings of the National Academy of Sciences, 108(38), 16050-16055.
4. Poutahidis, T., Kearney, S. M., Levkovich, T., Qi, P., Varian, B. J., Lakritz, J. R., . . . Erdman, S. E. (2013). Microbial Symbionts Accelerate Wound Healing via the Neuropeptide Hormone Oxytocin. PLoS ONE, 8(10).
5. Distrutti, E., Monaldi, L., Ricci, P., & Fiorucci, S. (2016). Gut microbiota role in irritable bowel syndrome: New therapeutic strategies. World Journal of Gastroenterology, 22(7), 2219-2241.
6. Oudenhove, L. V., Mckie, S., Lassman, D., Uddin, B., Paine, P., Coen, S., . . . Aziz, Q. (2011). Fatty acid–induced gut-brain signaling attenuates neural and behavioral effects of sad emotion in humans. Journal of Clinical Investigation,121(8), 3094-3099. doi:10.1172/jci46380
Emily Courtney is a Writer and Editor at Hyperbiotics and mom to two fun and active boys. Emily is passionate about natural wellness and helping others learn about the power of probiotics for vibrant health! For more ideas on how you can benefit from the power of probiotics and live healthier days, be sure to subscribe to our newsletter.