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Your Gut Is Running Your Mood — And Most People Have No Idea

Written by Fevin Reyes | May 15, 2026 3:15:29 PM

When I survived my stroke, I came out the other side with something no doctor prescribed — a bone-deep understanding that our bodies are our most valuable asset. I want you to feel that too, before something forces you to.

I lost part of my vision permanently from my stroke. I live with hemianopsia — half my visual field is gone. And while I'd never wish that on anyone, it cracked me open to truths about health that most people never encounter until it's too late.

One of the biggest? The reason you feel anxious, depressed, exhausted, or can't sleep at night may have very little to do with your mindset — and everything to do with what's living in your gut.

 

It Starts in a Place You'd Never Expect

Deep in your large intestine, there's a colony of roughly 100 trillion bacteria — about 500 different species — called your microbiome. Think of it as a secret organ your body never told you about.

These bacteria don't just help digest your food. They help run your entire system: your hormones, your immune function, your energy levels, your ability to build muscle, and — here's the part that floored me — your mood, your stress levels, and your ability to sleep deeply.


A healthy microbiome means a better shot at feeling calm, rested, and resilient. An imbalanced one? You feel it everywhere — and you probably already do.

 

Your Brain Runs on Chemicals Made in Your Gut

Your nervous system communicates through chemicals called neurotransmitters — messengers that travel between your 86 billion nerve cells to regulate how you think, feel, move, and rest. You've probably heard of some of them:


Now here's what most people are never told: most of these neurotransmitters are made in your gut.

About 95% of your body's serotonin is produced in the lining of your colon — through direct interaction with your gut bacteria. GABA? Produced directly by bacteria in your microbiome and absorbed into your nervous system.

Your gut bacteria are literally manufacturing the chemicals your brain needs to function. Let that sink in.

 

The Research Is Undeniable

When researchers removed gut bacteria from mice entirely and compared them to mice with a healthy microbiome, the results were staggering:

And in humans? People suffering from depression and anxiety consistently show distinctly different microbiome profiles — specific bacteria are elevated or depleted in very exact, measurable ways. Scientists can actually see the difference.

This isn't alternative medicine. This is science. And for those of us who've experienced brain-level trauma, it's deeply personal.

 

As a Stroke Survivor, This Changed Everything for Me

💙 Personal Note

When I was recovering from my stroke, nobody talked to me about my gut. Nobody connected my mood struggles, disrupted sleep, or elevated stress to what was happening in my digestive system.

But living with permanent hemianopsia — losing half of my visual field — taught me something powerful: the brain and body are one system. What happens in one place echoes everywhere else.

Protecting my gut is protecting my brain. Supporting my microbiome is supporting my nervous system, my recovery, and my resilience. This is why I say — over and over — that our bodies are our most valuable asset. We have to tend to them at every level, not just the parts we can see.

What You Can Actually Do About It

The good news? You have real power here. The bacteria that produce your calming neurotransmitters thrive on:

  1. Quality protein & essential amino acids — these feed the bacteria that produce GABA and serotonin. Ever feel calm and sleepy after turkey? That's tryptophan (an essential amino acid) feeding your GABA-producing bacteria.

  2. Greens and plant-based foods — fiber-rich vegetables give your beneficial bacteria the nutrients they need to thrive.

  3. Probiotics — especially important after antibiotic use or a period of poor diet. They help recolonize the bacteria your gut needs.

  4. Cut out processed sugars — they feed the wrong bacteria and disrupt the entire ecosystem.