Most people have heard the phrase “trust your gut,” but fewer realize just how literal that advice can be. The gut and the brain are in constant conversation—sending chemical, electrical, and hormonal messages back and forth all day long. This communication system is called the gut–brain axis, and understanding it helps clear up many misconceptions about mood, digestion, and why emotional wellbeing often begins with a healthy gut.

Your Gut Has Its Own Nervous System

The gut is home to a specialized nervous system—often called the “second brain.” It contains more than 100 million nerve cells, and research in John Hopkins Medicine shows that this system can function independently. It senses what’s happening inside the gut and sends instant feedback to the brain through the vagus nerve, our main mind–body communication highway.

This means sensations like “gut instinct,” tightness, butterflies, or nausea during stress aren’t imagined. They are real neurological signals, created by the same networks that help regulate digestion.

Your Gut Plays a Massive Role in Mood Chemicals

One of the most surprising facts is how many of our “feel-good chemicals” are influenced by the gut. Research published in Cell (Yano et al., 2015) shows that about 90% of the body’s serotonin is made in the gut, not the brain. Serotonin helps regulate mood, emotional balance, digestion, and sleep-wake cycles. While gut-made serotonin doesn’t cross into the brain, it communicates through nerves and immune pathways that shape how we feel.

Your microbiome—the trillions of microbes living in your intestinal tract—also helps produce neurotransmitters like GABA and acetylcholine. These chemicals help regulate calmness, focus, and emotional steadiness. So yes: the gut truly has the biochemical tools to influence your mind.

Your Microbiome Talks to Your Brain

Studies show that gut bacteria send signals that can affect stress responses, inflammation, sleep, and even decision-making. When your microbiome is diverse and thriving, these signals tend to promote steadier mood and calmer stress reactions.

When the microbiome is imbalanced—often due to stress, illness, antibiotics, or low-fiber diets—the messages it sends can shift. This helps explain why digestive issues and emotional changes often appear together.

Stress Starts in the Brain—but the Gut Feels It First

Stress may begin in the mind, but the gut often feels it before we do. The vagus nerve senses tension and triggers physical changes like slowed digestion, cramping, nausea, or appetite shifts. A study in Biological Psychiatry found that chronic stress can even alter microbiome diversity, which then sends different signals back to the brain that influence mood and resilience.

This two-way loop is exactly why emotional wellbeing and gut wellbeing are inseparable.

A Healthy Gut Helps Support a Healthy Mind

You don’t need a complicated routine to support your gut–brain axis. Evidence-backed steps include:

• Eating more fiber-rich foods to feed beneficial bacteria (PubMed, 2025)
• Adding fermented foods, which research shows can increase microbiome diversity (Science Direct, 2025)
• Getting consistent sleep to regulate microbiome rhythms and stress hormones
• Supporting gut balance with clinically studied prebiotics and probiotics

Your gut is not just a digestive organ—it’s a sensory, neurological, and biochemical control center that influences how you feel every day. When it’s nourished, the signals it sends to your brain can support calm, clarity, and steadier emotional wellbeing.

Your gut feelings aren’t “in your head.” They’re in your neurons, your microbes, and your biology—and now you know the science behind them.

References

Johns Hopkins Medicine — The Brain-Gut Connection (2025) The Brain-Gut Connection. Retrieved from https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-brain-gut-connection

PubMed. Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis. Yano JM, Yu K, Donaldson GP, et al (2015). Cell, 161(2), 264–276. doi:10.1016/j.cell.2015.02.047

Biological Psychiatry. Stress, inflammation, and gut microbiota — gut–brain axis review in Biological Psychiatry (2023) doi:10.1016/j.biopsych.2023.01.659

PubMed. The Gut-Brain Axis and Mental Health: How Diet Shapes Our Cognitive and Emotional Well-Being. The Gut-Brain Axis and Mental Health: How Diet Shapes Our Cognitive and Emotional Well-Being. Retrieved from https://pmc.ncbi.nlm.nih.gov/articles/PMC12366197/

ScienceDirect. Recent article on microbiome and gut–brain connection. (2025). Mahmut Bodur, Betül Kocaadam Bozkurt, Osman Bozkurt, et al. Retrieved from https://www.sciencedirect.com/science/article/abs/pii/S0955286325003572