When we think about intelligence and emotions, we usually picture the brain in our heads. But did you know that your body has another “brain” — in your gut?
Often called the second brain, the gut is home to the enteric nervous system (ENS) — a vast network of neurons embedded in the walls of the digestive tract. This system doesn’t just help you digest food; it also influences mood, memory, and even decision-making. And unlike any other part of the body, it can operate independently of the brain in your skull.
In this article, we explore why the gut has earned the title of the “second brain,” how this remarkable system functions, and what you can do to keep it thriving.
What Is the “Second Brain”?
The term second brain refers to the enteric nervous system (ENS) — a network of over 500 million neurons that line your gastrointestinal tract from oesophagus to anus. That’s more neurons than in the spinal cord [1].
What makes the ENS special is its autonomy. It can control gut behaviour — such as muscle contractions, enzyme secretion, and nutrient absorption — without needing instructions from the brain. Researchers have found that even when the vagus nerve (which links the brain and gut) is severed, the ENS can still function [2].
This independent system can sense the environment inside the gut, react to changes, and even learn from past experiences — which is why scientists sometimes call it a “mini-brain” [3].
The Gut Thinks, Feels, and Talks
Though the gut doesn’t “think” like we do, the ENS uses many of the same neurotransmitters as the brain — including serotonin, dopamine, and gamma-aminobutyric acid (GABA). In fact, around 90–95% of your body’s serotonin is found in the gut, where it helps regulate bowel movements, pain sensitivity, and mood [4].
This is one reason why gut issues like irritable bowel syndrome (IBS) are often linked with anxiety and depression — the ENS and the brain share a two-way communication channel through the gut-brain axis [5].
Additionally, the gut has a form of “emotional memory”. Studies show that stressful life events can change gut sensitivity or motility, and that calming the gut can sometimes ease mental health symptoms [6].
Why the Second Brain Matters
Far from being just a digestive organ, the gut plays a key role in:
- Mood regulation: Through serotonin and other neurotransmitters
- Stress response: By signalling cortisol release through the hypothalamic-pituitary-adrenal (HPA) axis.
- Cognitive health: Influencing memory, learning, and even neurodegenerative disease risk.
- Immunity and inflammation: About 70% of your immune system is located in the gut lining.
- Decision-making: Gut instincts are real — they’re guided by subconscious signals from your enteric system [7]
This means when your gut is out of balance, it may affect more than just digestion. You might notice mood swings, brain fog, sleep problems, or even immune issues.
How the Microbiome Shapes the Second Brain
Living inside your gut are trillions of bacteria, fungi, and other microbes — collectively known as the gut microbiome. These microbes don’t just break down food; they produce neuroactive compounds that can communicate directly with the ENS [8].
Certain species of gut bacteria can:
- Stimulate serotonin or GABA production.
- Influence how stress is processed.
- Modulate the immune system and brain inflammation.
- Affect how neurons fire in the brain and gut [9]
Because of this, maintaining a healthy gut microbiome is essential for the second brain to function properly.
How to Support Your Second Brain
Now that you know how powerful your gut really is, here are five key strategies to support it:
1. Feed It with Prebiotics
Prebiotics are types of fibre that “feed” the good bacteria in your gut, helping them flourish. Foods like garlic, onions, leeks, bananas, and oats are natural sources [10].
2. Include Fermented Foods
Probiotic-rich foods like yogurt, kefir, kimchi, and miso introduce live beneficial bacteria that interact with the ENS.
3. Manage Stress
Chronic stress can disrupt gut-brain communication and trigger inflammation. Practices like mindfulness, yoga, and breathing exercises can help calm the ENS.
4. Limit Ultra-Processed Foods
Diets high in sugar, additives, and artificial sweeteners can reduce microbial diversity and alter neurotransmitter production.
5. Consider Probiotic or Psychobiotic Supplements
Certain probiotic strains — sometimes called psychobiotics — have been shown to support mental well-being by interacting with the gut-brain axis.
The Bottom Line
Your gut is far more than a digestive tube — it’s a thinking, sensing, and communicating organ in its own right. This “second brain” plays a vital role in emotional balance, stress resilience, and mental clarity.
When supported with the right diet, lifestyle, and microbial care, your gut can help you feel better not just physically — but emotionally and mentally too.
So, the next time you say you have a “gut feeling”… trust it. Science is finally catching up to what we’ve instinctively known all along.
Connect with us on:
Available at:
References
- Furness, J.B. (2012) ‘The enteric nervous system and neurogastroenterology,’ Nature Reviews Gastroenterology & Hepatology, 9(5), pp. 286–294. https://doi.org/10.1038/nrgastro.2012.32.
- Gershon, M.D. (1999) ‘The enteric nervous system: a second brain,’ Hospital Practice, 34(7), pp. 31–52. https://doi.org/10.3810/hp.1999.07.153.
- Grundy, D. et al. (2006) ‘Fundamentals of Neurogastroenterology: Basic Science,’ Gastroenterology, 130(5), pp. 1391–1411. https://doi.org/10.1053/j.gastro.2005.11.060.
- Yano, J.M. et al. (2015) ‘Indigenous Bacteria from the Gut Microbiota Regulate Host Serotonin Biosynthesis,’ Cell, 161(2), pp. 264–276. https://doi.org/10.1016/j.cell.2015.02.047.
- The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems (2015). https://pubmed.ncbi.nlm.nih.gov/25830558/.
- Moloney, R.D. et al. (2013) ‘The microbiome: stress, health and disease,’ Mammalian Genome, 25(1–2), pp. 49–74. https://doi.org/10.1007/s00335-013-9488-5.
- Cryan, J.F. and Dinan, T.G. (2012) ‘Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour,’ Nature Reviews. Neuroscience, 13(10), pp. 701–712. https://doi.org/10.1038/nrn3346.
- Dinan, T.G. and Cryan, J.F. (2016) ‘Gut instincts: microbiota as a key regulator of brain development, ageing and neurodegeneration,’ The Journal of Physiology, 595(2), pp. 489–503. https://doi.org/10.1113/jp273106.
- Strandwitz, P. (2018) ‘Neurotransmitter modulation by the gut microbiota,’ Brain Research, 1693, pp. 128–133. https://doi.org/10.1016/j.brainres.2018.03.015.
- Slavin, J. (2013) ‘Fiber and Prebiotics: Mechanisms and health,’ Nutrients, 5(4), pp. 1417–1435. https://doi.org/10.3390/nu5041417.
