Are the gut and brain connected? Science confirms this link — and it is deeper than most people imagine.
Have you ever noticed how, during moments of anxiety or stress, your gut tends to react? That “butterflies in the stomach” feeling, intestinal discomfort, or changes in digestive rhythm are not mere coincidences. Science confirms that there is direct communication between the gut and the brain — known as the gut–brain axis — which plays a fundamental role in mental health.
The “Second Brain” Living in the Gut
The gut contains a vast network of neurons known as the enteric nervous system. It is so complex that, in 1996, American neuroscientist Dr. Michael Gershon, from Columbia University, referred to it as the “second brain,” becoming one of the first researchers to defend the gut’s autonomous importance in emotional regulation. Gershon popularized the phrase:
“We have more neurons in the gut than in the spinal cord.”
Although the claim that there are “more neurons than in the brain” is often repeated in popular contexts, the accurate figure is that the gut houses around 100 million neurons — fewer than the brain, but more than many other organs, underscoring its enormous importance.
The Gut Microbiota and Neurotransmitters
Beyond neurons, the gut is home to trillions of beneficial bacteria that make up the gut microbiota. These bacteria produce substances such as serotonin, dopamine, and gamma-aminobutyric acid (GABA) — neurotransmitters that communicate with the brain and are directly linked to mood, sleep, motivation, and feelings of well-being, while also playing metabolic and immune roles.
It is estimated that about 90% of the body’s serotonin is produced in the gut. This means that an intestinal imbalance — known as dysbiosis — can directly affect emotional balance.
When the Gut Suffers, the Mind Feels It
Dysbiosis occurs when beneficial bacteria decrease and harmful bacteria increase. This imbalance can lead to inflammation, increased intestinal permeability, and the release of toxins that affect the brain. The result may include irritability, anxiety, depression, and even cognitive problems.
This relationship works both ways: negative emotional states also affect the gut, causing symptoms such as constipation, diarrhea, gas, and abdominal pain. When the gut is unwell, the mind feels it — and vice versa.
Neurological Conditions Under Study
Recent studies suggest that microbiota imbalance may be linked to conditions such as depression, anxiety, autism, and Parkinson’s disease. While definitive conclusions have not yet been reached, science has increasingly demonstrated how gut bacteria influence brain function and behavior.
Diagnosis and Treatment
Noticing changes in bowel habits, bloating, gas, and frequent emotional discomfort may signal an imbalance. Tests such as the breath test for small intestinal bacterial overgrowth (SIBO) and routine checkups — including blood, stool tests, and even colonoscopy — can help detect irregularities early.
Treatment may include targeted antibiotics, probiotic supplementation, dietary changes, and stress management. Medical supervision is essential.
How to Protect the Gut–Brain Axis
To care for the mind, you must care for the gut. Recommended practices include:
• Consume fiber (fruits, vegetables, and whole grains).
• Include fermented foods (such as kefir, plain yogurt, sauerkraut, kombucha).
• Reduce ultra-processed foods.
• Eat slowly and chew thoroughly.
• Exercise regularly and prioritize quality sleep.
• Reduce stress through techniques such as meditation or mindful breathing.
Science no longer has doubts: the gut directly influences mood, cognition, and emotional balance. While it is not the sole factor in mental health, it is a key piece for those seeking overall well-being. As Dr. Gershon stated, understanding the gut as a “second brain” is essential for a new way of caring for both body and mind.
The full study is cited in the article’s source at the following link: National Library of Medicine