The Gut-Brain Connection

You’ve probably heard the phrase “gut-brain connection” before. It appears in articles, podcasts, and supplement advertisements. But what does it truly feel like to experience that connection?

If you’ve ever noticed changes in your digestion during a stressful week or felt unexpectedly anxious after a meal that you typically tolerate, then you already have a sense of this link. It’s more than an abstract concept; it's physical and emotional. This connection often develops more gradually and messily than most people anticipate.

As a functional nutritionist, I don’t view the gut-brain connection as a concept to be “optimized.” Instead, I see it as a relationship that needs nurturing. Like any complex relationship, it requires observation, honesty, and sometimes some space to renegotiate its terms.

Here are various ways in which the gut and brain influence one another, along with some less obvious entry points that I keep in mind when supporting this connection.

1. Mornings set the microbial tone

Many people view morning routines primarily as a form of mental hygiene, encompassing activities such as journaling, stretching, and taking cold showers. However, from a microbial standpoint, the first 90 minutes of your day play a vital part in how your gut communicates.

If you start your day by checking messages in bed, skipping breakfast, and rushing through your coffee on an empty stomach, your body interprets these actions as signals that it needs to conserve energy. These signals not only indicate stress but also a sense of unpredictability. Microbes benefit from predictability, and your gut, which is connected to your brain's circadian rhythm, continuously adapts to your daily patterns.

I often ask my clients: What is your gut learning from your morning habits?

2. Mood symptoms may be gut flare-ups in disguise

Sometimes, the most telling sign of a gut imbalance isn't bloating or reflux; it's feelings of irritability, apathy, or an unexplainable feeling of doom that seems to hit around 3 pm.

Clients often report, “I feel fine in the morning, but by late afternoon, I feel completely overwhelmed.” Frequently, there’s no clear trigger, whether it be a specific food or an external stressor. However, upon closer examination, we identify a pattern: an inflamed, overloaded, or dysregulated microbiome that sends signals upward to the nervous system.

It's helpful to consider the question: Is this mood genuinely mine, or is it originating from a deeper issue within my body?

3. Constipation changes cognition

Slowed digestion not only impacts the colon; it can also affect cognitive function. When the gut is sluggish, it can impair thinking, decrease motivation, and subtly change how we perceive our surroundings.

I've had clients describe this experience as feeling "like I'm underwater" or "watching my day instead of living it." Many are surprised to find that a bowel movement can greatly clear this mental fog.

This phenomenon isn't just a placebo effect; it involves biochemistry. Toxins and neurotransmitters circulate differently based on what is moving (or not moving) through the system. A sluggish gut can lead to a sluggish mind.

4. A gut that doesn’t feel safe won’t digest well

Digestion is closely linked to the state of the nervous system. When your body feels unsafe, your gut doesn’t receive the signals it needs to digest, assimilate, or repair itself properly.

So, what does it mean to feel “safe” in this context? It’s not only about feeling relaxed; it also involves predictability, warmth, and a sense of sufficiency. It's about making sure that your body isn’t in a state of high alert.

This feeling of safety might come from enjoying a calm dinner environment, knowing that you won’t check your phone while eating, or giving yourself permission to eat something without feeling guilty.

Safety is contextual, and your gut senses all of these factors.

5. Microbial diversity affects emotional range

The diversity of your microbiome appears to enhance the flexibility of your brain, affecting not only mood regulation but also emotional capacity. This connection is supported by research and evident in clients' experiences: "I used to spiral for hours, but now it feels more like just a passing wave." "I still get overwhelmed, but I recover more quickly."

These changes are more than shifts in mindset; they likely involve microbial influences as well. Microbial diversity is not only a sign of gut health -- it may also determine the extent of emotional endurance you can maintain without feeling destabilized.

6. Social withdrawal can signal microbiome depletion

When someone says, “I don’t feel like seeing anyone,” we often associate it with depression or burnout. However, I have learned to ask: what’s your gut been up to lately?

A sluggish microbiome can dampen reward processing, reduce dopamine signaling, and make basic social interactions feel challenging. That disinterest in small talk and resistance to eye contact might derive from a nervous system overwhelmed by internal noise.

7. Microbiome repair supports mental resilience, not perfection

There is a common misconception that healing the gut will lead to permanent calmness or boundless energy. In reality, what most people experience is a form of expansion: a greater space between stimuli and reactions, increased flexibility, and reduced rigidity. Your gut doesn’t eliminate difficult days, but it can help you face them with greater resilience. For most of us, that is what true resilience looks like.

When people ask whether the gut-brain connection is “real,” I don’t point them to a study. Instead, I ask them to describe what changes they have experienced in their bodies during times of grief, burnout, or transition. Most people have an understanding; they just lack the words to express it.

Content Copyright © 2026, MBK Cultivate Skin & Nutrition Wellness   

PERMISSION TO REPRINT: You may use any items from this article in your print, blog, magazine, or electronic newsletter. However, you must include the following paragraph, which should contain a link to www.mebykatie.com.   

"Information courtesy of www.mebykatie.com; Katie Marshall is a certified Medical Esthetician, Acne Specialist, Functional Nutrition Counsellor, Holistic Chef, and Integrative Nutrition Health Coach. Specializing in skin health, gut health, hormone health, and the whole body. The basic premise is that functional nutrition addresses the root cause of the problem and resolves the underlying issue. This differs from conventional medicine, which often prescribes multiple medications to address symptoms, with little regard for resolving their underlying causes. Functional nutrition is more personalized, customized, and holistic in approach. My job is to work with your medical team and advocate for you if necessary."   

Health/Medical Disclaimer:   

The content of MBK Cultivate Skin & Nutrition Wellness, either through these social media pages, websites, or any other materials distributed by MBK Cultivate Skin & Nutrition Wellness, is intended to provide helpful and informative material. Please note that my personal and professional opinions expressed on these social media pages and websites are entirely my own. This site provides information on skin, diet, fitness, health, and nutrition, and is intended in good faith for educational purposes only. Care has been taken to confirm the accuracy of the information and describe generally accepted practices. However, the authors, editors, and publishers are not responsible for errors, omissions, or any consequences from the application of the information in these publications and make no warranty, expressed or implied, concerning the currency, completeness, or accuracy of the publication's contents. It would be best not to rely on this information as a substitute, nor does it replace professional medical advice, diagnosis, or treatment.   

I, Katie Marshall, am not a doctor or medical provider and do not provide medical advice. Readers are advised to research and make decisions in partnership with their healthcare provider.   

If you are pregnant, nursing, have a medical condition(s), or take any medication(s), please consult your family physician.   

Always consult your family physician or other qualified healthcare providers with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you read on my social media pages or websites.   

If you have a medical emergency, call your family physician, go to the nearest emergency department, or call 911 immediately. Reliance on any information provided by MBK Cultivate Skin & Nutrition Wellness or Katie Marshall, or on content presented for publication on these social media pages or websites, is solely at your own risk. Administrators and Moderators are not liable for your actions.   

Health Canada & FDA Disclaimer:   

Neither Health Canada nor the Food and Drug Administration has evaluated the advice and statements on this page.