12/10/2025
GUT CHAT: Understanding the Gut–Brain Axis
Trust Your Gut – There’s Science Behind It
You’ve probably heard the phrase “trust your gut.” It turns out that’s more than old wisdom — it’s physiology.
The gut isn’t just a digestive tube; it’s an information hub that constantly talks to your brain. Around 90–95% of your serotonin— the neurotransmitter linked with mood, motivation, and sleep — is produced in your gut by specialised cells and bacteria.
So when your gut is out of balance, your brain feels it too. Low mood, brain fog, poor motivation, disrupted sleep — these can all start in the gut before they ever reach your head.
The connection between the gut and brain is called the gut–brain axis, and it’s one of the most exciting areas in modern health science.
It explains why your digestion, immune system, and mood are all part of the same conversation — a conversation that runs along a remarkable nerve called the vagus nerve.
The Two-Way Conversation Between Gut and Brain
The gut and the brain talk in both directions. Signals travel through nerves, hormones, and immune messengers. When your gut bacteria are balanced and your intestinal lining is healthy, this communication runs smoothly.
When inflammation or stress disturb that system, the messages get distorted — leading to digestive issues, fatigue, anxiety, or even depression.
Stress is one of the biggest disruptors of gut integrity. Chronic stress lowers blood flow to the intestines, weakens the gut barrier, and increases inflammation.
That in turn affects the blood–brain barrier (BBB), allowing inflammatory compounds to reach the brain and trigger what’s known as neuroinflammation.
Neuroinflammation blunts neurotransmitter production, disrupts sleep, increases cravings, and drains energy. It’s a vicious loop — stress damages the gut, the gut alters brain chemistry, and the brain sends more stress signals back to the gut.
The antidote is restoring communication through two main systems:
• The microbiome (your population of gut bacteria)
• The vagus nerve (your internal communication line)
Meet Your Microbiome: The Inner Ecosystem
Inside your gut live roughly 100 trillion microbes — bacteria, yeasts, and other organisms collectively called the microbiome. They outnumber your human cells ten to one, and they have a huge impact on your metabolism, immunity, and mental state.
A healthy microbiome:
• Produces neurotransmitters such as serotonin, dopamine, and GABA
• Regulates inflammation through short-chain fatty acids (SCFAs)
• Protects the intestinal wall
• Supports balanced blood sugar and energy
When your microbiome loses balance — a state called dysbiosis — inflammatory bacteria take over, the gut lining becomes “leaky,” and undigested food particles or toxins can pass into the bloodstream. This immune activation can drive fatigue, poor focus, joint pain, and low mood.
One striking fact: germ-free mice (bred with no gut bacteria) show higher anxiety and less curiosity than those with healthy microbial colonies. When researchers transplant balanced bacteria into their guts, their behaviour normalises. The gut literally changes behaviour.
How Diet Shapes the Microbiome
Your gut bacteria eat what you eat. Diet is the fastest way to shape the microbiome — changes can occur within 24 hoursof switching foods.
• High-fibre, diverse plant diets feed beneficial bacteria and increase species diversity.
• High-sugar, low-fibre diets feed inflammatory microbes and reduce diversity.
• Fermented foods (such as kefir, kimchi, sauerkraut, and live yogurt) introduce beneficial bacteria and natural enzymes.
• Resistant starches (from cooled potatoes, oats, beans, and green bananas) act as prebiotics — fuel for friendly microbes.
A healthy, diverse microbiome is like a thriving rainforest. A damaged one is like a monoculture farm — overworked, stripped of nutrients, and vulnerable to weeds.
Aim for at least 30 different plant foods per week. That includes herbs, spices, seeds, nuts, and vegetables. It’s easier than it sounds — a sprinkle of mixed seeds, a handful of berries, and a colourful salad quickly rack up your count.
Short-Chain Fatty Acids: The Unsung Heroes
When your gut bacteria ferment fibre, they produce short-chain fatty acids (SCFAs) like butyrate, propionate, and acetate. These are powerful anti-inflammatory molecules that:
• Strengthen the intestinal barrier
• Protect the blood–brain barrier
• Support serotonin and dopamine production
• Reduce systemic inflammation
Low SCFA levels are linked with anxiety, depression, and neurodegeneration. You can boost them naturally by eating fibre-rich vegetables, pulses, nuts, and resistant starches.
Amino Man clients often combine this approach with amino acid-based gut repair nutrients such as glutamine, zinc carnosine, and collagen peptides — nutrients that help rebuild the intestinal lining and support immune regulation.
Inflammation, Mood, and the “Tryptophan Steal”
When the immune system is constantly switched on, inflammation can divert the amino acid tryptophan — normally used to make serotonin — down another biochemical route called the kynurenine pathway.
This process, often nicknamed the “tryptophan steal,” lowers serotonin levels and can lead to low mood, fatigue, and sleep issues.
Reducing inflammation helps bring that pathway back into balance. Practical ways to do that include:
• Eating anti-inflammatory foods (berries, oily fish, turmeric, olive oil, and dark leafy greens)
• Avoiding processed fats and sugars
• Supporting gut integrity with L-glutamine, omega-3s, and probiotics
• Managing stress through breathwork, meditation, or time outdoors
Inflammation doesn’t just happen in the gut — it’s a whole-body communication signal. Calming it through lifestyle and nutrition is one of the fastest routes to better mood and clearer thinking.
The Vagus Nerve: Your Inner Superhighway
The vagus nerve runs from your brainstem through your lungs, heart, and digestive organs. It’s the main channel of the parasympathetic nervous system — the “rest, digest, and recover” branch that counterbalances stress.
When vagal tone is strong, you digest well, feel calm, and recover faster. When it’s weak, you may experience anxiety, gut disturbances, or chronic tension.
Ways to Strengthen Vagal Tone
• Deep, diaphragmatic breathing (especially longer exhales)
• Singing, humming, or chanting
• Cold exposure (a cold shower or splash of cold water on the face)
• Gentle yoga or tai chi
• Massage and touch
• Gratitude and positive social connection
• Regular exercise and restorative sleep
Supporting the gut–brain axis means training your vagus nerve just as deliberately as you train your muscles. Every breath and every mindful meal strengthens that system.
From Leaky Gut to Leaky Brain
Your gut lining is just one cell thick, and it regenerates rapidly — roughly every three days. It’s made mostly from amino acids like glutamine, glycine, and threonine. When inflammation, infections, or poor diet damage this lining, it becomes “leaky,” allowing particles to pass through.
This same mechanism can affect the blood–brain barrier (BBB), creating “leaky brain.” Once inflammatory molecules cross that line, they can trigger fatigue, brain fog, and neuroinflammation.
The fix is straightforward but consistent:
• Remove irritants (excess alcohol, processed foods, and artificial sweeteners)
• Replace with whole, unprocessed, nutrient-rich foods
• Reinoculate the gut with probiotics and prebiotics
• Repair the lining with amino acids, collagen, and polyphenol-rich plants
This is known as the 4R approach: Remove, Replace, Reinoculate, Repair.
It’s a framework Amino Man often uses when supporting clients with digestive or cognitive issues.
The Apple Skin Story – Feeding Your Friendly Bacteria
Among the many beneficial microbes, Akkermansia muciniphila stands out. It helps maintain gut barrier integrity and metabolic health, and it thrives on polyphenols — particularly those in red apple skins.
So the old saying “an apple a day keeps the doctor away” may have a microbial truth behind it. Red apples, berries, and colourful plant foods nourish the species that keep your gut lining intact.
Gut Health and Metabolism
Your microbiome doesn’t just influence mood — it directly affects metabolism and energy.
Studies show that obese individuals often have less microbial diversity and more bacteria that extract energy from food, promoting weight gain. Balanced gut bacteria help regulate insulin sensitivity, fat storage, and appetite hormones.
In practical terms:
• A diverse, fibre-rich diet supports metabolic flexibility.
• Regular exercise boosts microbial diversity and SCFA production.
• Combining exercise with gut-support nutrients can enhance both recovery and mental wellbeing.
In the Amino Man philosophy, metabolic health, gut health, and brain health are part of the same triangle — you can’t optimise one without addressing the others.
Antibiotics, Inflammation, and “Awakenings”
One remarkable story illustrates how gut inflammation links to brain function. In a dementia case study, a patient temporarily regained clarity and memory after receiving intravenous antibiotics.
The theory: by reducing gut inflammation and bacterial toxins, the brain’s inflammation dropped, restoring communication temporarily.
While antibiotics aren’t a long-term strategy, the case underscores how gut inflammation drives neuroinflammation.
A clean, balanced gut ecosystem supports the brain’s ability to repair, regenerate, and maintain mental sharpness.
Feeding Your Gut for Mental Clarity
Here’s a practical checklist to keep your gut–brain axis firing on all cylinders:
Top 8 Gut Habits
1. Chew thoroughly and eat in a relaxed setting.
2. Load up on vegetables — aim for colour diversity.
3. Include fibre (beans, oats, nuts, seeds, whole grains).
4. Add fermented foods daily.
5. Include polyphenol-rich foods (berries, olive oil, herbs, spices).
6. Balance plant and animal protein — avoid excess processed meat.
7. Stay hydrated and limit alcohol.
8. Support gut health with probiotics, omega-3s, and amino acids like glutamine.
Avoid These Gut Stressors
• Chronic stress and shallow breathing
• Excess caffeine or alcohol
• Artificial sweeteners
• Repeated antibiotics without replenishment
• Sleep deprivation
Lifestyle Tools to Boost the Gut–Brain Axis
• Exercise – increases microbial diversity and strengthens the vagus nerve.
• Intermittent fasting – gives the gut lining time to repair and enhances metabolic balance.
• Breathwork or meditation – activates the parasympathetic system and improves vagal tone.
• Cold exposure – stimulates norepinephrine and reduces inflammation.
• Amino acid support – ingredients like tryptophan, tyrosine, glycine, and glutamine provide the raw materials for neurotransmitter and gut lining repair.
Key Nutrients and Supplements to Support the Gut–Brain Axis
• Glutamine – primary fuel for gut cells, helps repair leaky gut.
• Zinc Carnosine – clinically shown to support gut barrier function.
• Beta-Alanine a precursor to carnosine.
• Omega-3 Fatty Acids – anti-inflammatory, support brain and gut membranes.
• Probiotics – restore healthy microbial balance.
• Polyphenols – from plants, tea, coffee, and dark chocolate.
• Beta-glucans and inulin – prebiotic fibres that feed good bacteria.
• Amino acid complexes – foundational support for neurotransmitter synthesis.
These are the kind of evidence-based ingredients found in many Amino Man formulations, designed to help rebuild the gut–brain link from the inside out.
Closing Thoughts: Your Second Brain Deserves Training Too
The gut–brain axis isn’t a theory — it’s a two-way communication network that shapes how you think, feel, and perform.
You can’t separate mental clarity from digestion or emotional balance from inflammation.
By combining gut-friendly nutrition, mindful stress management, and consistent exercise, you strengthen every level of the system — from microbial diversity to neurotransmitter balance.
Think of it like training:
• Feed your microbes with fibre and polyphenols.
• Calm your vagus nerve with breathwork and gratitude.
• Fuel your brain with clean proteins, omega-3s, and amino acids.
When you support the gut, the brain follows — sharper, calmer, stronger.
And that’s not just a gut feeling.
Natural formulas to support health and fitness goals created by Elite Nutritionist, Matt Lovell. Sleep, recover, perform and train better. Amino Acid, vitamin, mineral and botanical formulas designed for elite performers.
