The Gut-Brain Connection: How Your Digestive Health Impacts Mood, Anxiety, and Mental Clarity

During my teenage years, I rarely considered how the food I ate might affect my health—especially my mental health. I had a sweet tooth like no other. Like most teens, I’d buy sweets after school, treat chocolate like it was its own food group, and demolish tubs of ice cream at sleepovers until I felt physically sick.

Back then, I thought food was just something to keep you full—or a quick fix when you were stressed. If I was tired, I figured I hadn’t slept enough. If I felt low or anxious, I blamed stress or hormones. Food, I assumed, had nothing to do with it. What I didn’t realise was that my diet was playing a massive role in how I felt mentally.

I would binge on sugar-laden snacks or salty, processed foods and then find myself crashing emotionally. I was moody, anxious, and often overwhelmed—and although I suffered greatly with IBS, I couldn’t see the connection between my brain and gut.

It wasn’t until I lost my period and dove headfirst into the world of nutrition and holistic health that I discovered the relationship between my gut and brain - something called the gut-brain axis.

And once I started to work with my body, rather than unknowingly against it, everything began to shift.

This blog post is for anyone who’s ever thought, “Why do I feel off?” without any obvious reason—because sometimes, the answer lies in your gut.

The Gut-Brain Connection: What Is It, Really?

The gut-brain connection refers to the complex communication network between your gastrointestinal (GI) system and your central nervous system (CNS)—specifically, your brain. This two-way highway of signals is how your gut and brain constantly keep each other updated on what’s happening in your body.

And this connection runs deeper than most people realise.

During early fetal development, both the brain and the gut actually form from the same type of embryonic tissue—called the ectoderm. Embryonic tissue is essentially the building block material that forms all of our body’s organs and systems in the womb. The fact that the brain and gut share this common origin helps explain why they’re so closely linked—even after they’ve developed into separate systems.

As the body grows, the brain and gut begin to specialise, but they stay in constant communication through an intricate web of nerves, hormones, and chemical messengers. This developmental bond is one of the reasons the gut is often referred to as the “second brain.”

It’s not just metaphorical when we talk about “gut feelings”—there’s a real, biological relationship at play.

How the Gut-Brain Connection Works

The relationship between the gut and the brain is incredibly dynamic—and it all starts with what’s living in your gut.

1. The Gut Microbiome: Your Internal Ecosystem 🌱

Your gut is home to trillions of microorganisms—mostly bacteria, but also fungi, viruses, and other microbes—collectively known as the gut microbiome. This diverse microbial community helps digest your food, regulate your immune system, protect against pathogens, and produce essential nutrients.

But beyond those roles, your microbiome also plays a key part in mental and emotional wellbeing. Certain strains of bacteria can influence your mood, memory, and stress levels, while others may promote inflammation and increase the risk of mental health struggles if they become too dominant. The balance of “good” and “bad” microbes matters—a lot.

Gut microbes aren’t just passive residents—they’re chemically active. They produce compounds that interact with your nervous system and influence how you feel on a daily basis.

Here are a few of the most important ones:

Neurotransmitters 🧠:

Around 90–95% of serotonin—your feel-good, mood-regulating neurotransmitter—is produced in the gut, not the brain. Gut bacteria help produce and modulate serotonin levels, along with other key neurotransmitters like dopamine (responsible for feelings of motivation and pleasure) and GABA (responsible for calming the nervous system and reducing anxiety). When your gut microbiome is thriving, these feel-good chemicals are more balanced too.

Short-Chain Fatty Acids (SCFAs) 🥦:

When your gut microbes break down fibre from plant-based foods, they produce short-chain fatty acids—like butyrate, acetate, and propionate. These compounds play a crucial role in maintaining a healthy gut lining, reducing inflammation, and even supporting brain function. SCFAs can influence how genes are expressed, help regulate the immune system, and may even reach the brain via the bloodstream—helping to protect against mood disorders, brain fog, and neuroinflammation. A fibre-rich diet feeds the good bacteria that produce these powerful, brain-supportive compounds.

Toxins & Inflammatory Molecules ⚠️:

When the gut microbiome becomes imbalanced—due to things like poor diet, stress, antibiotics, or infections—certain harmful bacteria can overgrow and begin producing toxic by-products. These substances can irritate the gut lining, increase intestinal permeability (a.k.a. “leaky gut”), and trigger an inflammatory response. Some of these inflammatory molecules can enter the bloodstream and make their way to the brain, where they may contribute to symptoms like low mood, anxiety, fatigue, and brain fog. Keeping your gut balanced and supported helps reduce this systemic inflammation and its mental health ripple effects.

2. The Vagus Nerve: The Gut-Brain Superhighway 🚗

The vagus nerve is the primary nerve connecting the brain and the gut. It is the longest cranial nerve in the body (meaning it emerges directly from the brain), running from the brainstem all the way down through the neck and chest into the abdomen, directly linking the two organs.

Many of the neurotransmitters and microbial by-products mentioned above can stimulate receptors in the gut lining which activates the vagus nerve, which then sends electrical signals up to the brain, influencing mood, emotional regulation, stress responses, and even memory and decision-making.

In fact, studies have shown that certain probiotics can only affect mood and behaviour if the vagus nerve is intact—meaning the gut-brain dialogue literally depends on that connection.

So, when we talk about the gut-brain connection, we’re really talking about how your gut microbes:

• Create neuroactive compounds 🧬

• Modulate inflammation 🔥

• Send signals through the vagus nerve⚡️

All of this adds up to a profound influence on your emotional and cognitive wellbeing—making your gut a powerful player in how you think and feel every day.

Mental Symptoms That Could Be Linked to Gut Health

You may be surprised to learn how many mental and emotional symptoms can be linked to gut health. Here are some common ones:

1. Brain Fog 💭

That cloudy, fuzzy, can’t-think-straight feeling? It’s often tied to blood sugar imbalances, inflammation, or dysbiosis (an imbalance in the gut microbiome). When your gut isn’t functioning properly, the brain doesn't receive the fuel and messaging it needs to stay sharp.

2. Low Mood or Depression 😞

Studies have shown that people with depression often have a different composition of gut bacteria compared to those without. An inflamed gut can disrupt the production of serotonin and other mood-regulating chemicals.

3. Anxiety 😰

The gut-brain axis plays a huge role in regulating anxiety. Gut bacteria influence the stress response and the production of calming neurotransmitters like GABA. If your microbiome is out of balance, your nervous system can feel more on-edge.

4. Irritability and Mood Swings 😡

Fluctuating blood sugar levels (often caused by diets high in refined carbs and sugar) can cause mood highs and lows. Combine that with poor gut function and inflammation, and it's a recipe for emotional turbulence.

5. Poor Stress Resilience 😖

A healthy gut helps modulate the body’s stress response. When the gut is compromised, you may find it harder to cope with even minor stressors, leading to burnout or feeling emotionally overwhelmed.

6. Fatigue and Lack of Motivation 💤

If your digestion isn’t working properly, your body can struggle to absorb key nutrients like B vitamins, iron, magnesium, and omega-3s—all crucial for brain function and energy production.

Why Does This Happen? The Science Behind It

Let’s break it down a bit more:

• Inflammation 💥: Chronic inflammation in the gut—often due to poor diet, alcohol, food intolerances, or stress—can trigger the release of inflammatory molecules (like cytokines). These molecules can cross into the brain and affect mood-regulating pathways.

• Nutrient Deficiencies 🍎: Many essential nutrients for brain function are absorbed in the gut. However, if your gut lining is damaged or your digestive enzymes aren’t working effectively, your body might struggle to absorb key nutrients - leading to deficiencies that can impact mental health.

• Microbiome Imbalance ⚖️: when there’s dysbiosis (too many “bad” microbes and not enough “good” ones), it can reduce the production of short-chain fatty acids—compounds that are anti-inflammatory and protect the brain. It also interferes with neurotransmitter production (especially serotonin) and can dysregulate the immune system.

• Stress: Chronic stress slows down digestion and alters gut motility, leading to symptoms like bloating, constipation, or diarrhoea. It also raises cortisol levels, which can further damage the gut lining and upset the microbiome.

How Nutritional Therapy Can Support Mood, Mental Clarity & Anxiety

This is where nutritional therapy becomes an absolute game-changer. Instead of trying to “fix” your mood with quick fixes or just focusing on the brain, nutritional therapy takes a root-cause approach—looking at the whole body, especially the gut.

Here’s how it helps:

1. Restoring Gut Health

Through diet and lifestyle recommendations, nutritional therapists support digestion and rebalance the microbiome. This might include:

• Adding in prebiotic and probiotic foods (e.g., fermented foods, fibre)

• Identifying and reducing food intolerances or triggers

• Supporting stomach acid and digestive enzymes

2. Balancing Blood Sugar

Keeping your blood sugar stable is key for emotional regulation. Nutritional therapy can help you:

• Build meals that contain quality protein, healthy fats, and fibre

• Avoid energy crashes and mood swings

• Reduce sugar and processed carb intake gradually and sustainably

3. Supporting Nutrient Status

We assess whether you're getting enough of the key nutrients your brain needs to thrive. Common ones include:

• Omega-3 fatty acids (anti-inflammatory, support mood)

• Magnesium (calms the nervous system)

• B vitamins (energy production and mental clarity)

• Zinc and iron (neurotransmitter support)

4. Reducing Inflammation

By helping you identify what might be causing inflammation in your body and altering your diet to increase anti-inflammatory food choices (like leafy greens, berries, oily fish), we reduce the systemic inflammation that contributes to mental fog and low mood.

5. Lifestyle & Nervous System Support

Nutritional therapy doesn’t just stop at food. It often incorporates lifestyle support to calm the nervous system, such as:

• Encouraging mindful eating practices and activation of the vagus nerve (‘’rest and digest’’)

• Stress management tools (like breathwork or grounding)

• Sleep hygiene guidance

Final Thoughts: Listening to Your Gut—Literally

If you're feeling low, anxious, mentally foggy, or just not quite yourself, it’s worth considering the role your gut might be playing. Gut health has a powerful influence on the brain, and it's often overlooked when thinking about mental and emotional wellbeing.

The good news? Supporting your gut doesn’t require a complete lifestyle overhaul. Small, mindful changes can make a big difference. Start by noticing how certain foods affect your mood, energy, and focus.

Tuning into your gut—both physically and intuitively—can offer valuable insight into what your body and mind really need. Sometimes, those “gut feelings” are more accurate than we think.

Need support with your gut health or mood?
I offer personalised nutritional therapy sessions where we explore your unique needs and create a plan that fits your lifestyle. If you would like advice on how to improve your gut health and mood then please reach out via the ‘Book Now’ page on my website or via direct message on Instagram to @mindfulnutritionie 😊

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Thanks for reading,

Mindful Nutrition x