The Gut-Brain Axis: How your Diet affects Mental Health and Mood.
Let me start with something I hear almost every week in clinic:
“Becki… I’m not ill. I’m just exhausted, anxious, bloated, foggy and not myself anymore.”
Sound familiar?
If you’ve been dealing with low mood, anxiety, digestive issues, cravings, fatigue or brain fog — you are not weak, broken or ‘just getting older’.
Very often, your gut is quietly running the show.
And when your gut isn’t happy… neither is your brain.
Welcome to the powerful (and often misunderstood) world of the gut–brain axis.
What Is the Gut–Brain Axis (And Why It Matters for Your Mental Health)?
Your gut and brain are in constant communication.
They talk through:
✔️ Nerves (especially the vagus nerve)
✔️ Hormones
✔️ Immune signals
✔️ Gut bacteria
This two-way system is called the gut–brain axis — and it plays a huge role in:
Anxiety
Depression
Stress resilience
Focus
Motivation
Sleep
Energy
Here’s the fascinating part:
Around 80% of your serotonin (your “feel-good” chemical) is made in your gut.
Not in your brain.
In your digestive system.
So if your gut is inflamed, irritated or imbalanced, your mood chemistry often suffers too.
This is why gut health and mental health are inseparable.
When “Trust Your Gut” Stops Working
Many of my clients come to FIT saying:
“I feel on edge all the time.”
“My digestion is unpredictable.”
“My mood crashes for no reason.”
“I’m tired even after sleeping.”
“Coffee is keeping me alive.”
Behind the scenes, I often see:
Food reactions
Gut inflammation
Poor microbiome diversity
Stress overload
Nutrient depletion
Nervous system burnout
When this happens, your body stays in low-level survival mode.
That affects:
Serotonin production
Stress hormones
Blood sugar
Sleep quality
Energy metabolism
Result?
You feel anxious, flat, overwhelmed and disconnected from your old self.
Why Guessing With Diets Rarely Fixes the Problem
Let’s talk honestly about “trial-and-error” dieting:
❌ Cut gluten
❌ Cut dairy
❌ Cut sugar
❌ Cut carbs
❌ Cut everything
❌ Feel miserable
❌ Still feel unwell
Sound familiar?
Random restriction rarely heals the gut.
That’s why, at FIT, I focus on testing before guessing — using practitioner-guided food intolerance testing with YorkTest.
IgG food intolerance testing helps identify foods that may be quietly triggering immune reactions and inflammation.
When we remove the right foods (not all foods):
Inflammation reduces
The gut lining repairs
Microbes rebalance
Energy improves
Mood stabilises
Clients often say:
“I can’t believe how different I feel.”
Calm the Gut, Lift the Mood: How We Rebuild at FIT
Once trigger foods are removed, we don’t stay in “avoid mode”.
We rebuild.
We nourish.
We strengthen.
We restore.
Here are the key gut–brain nutrients I focus on with clients:
Omega-3 Fatty Acids
Anchovies, sardines, mackerel, chia, flax, walnuts
Support brain health and reduce inflammation linked to anxiety and IBS.
Magnesium
Pumpkin seeds, almonds, spinach, dark chocolate
Essential for relaxation and nervous system balance.
B Vitamins (B6, B9, B12)
Salmon, eggs, lentils, chickpeas, nutritional yeast
Needed for serotonin and dopamine production.
Zinc & Iron
Beef, pumpkin seeds, tofu, liver, mussels, spinach
Support energy, focus and motivation.
Tryptophan-Rich Foods
Turkey, tuna, oats, eggs, cottage cheese
Provide raw material for serotonin.
Prebiotics & Polyphenols
Garlic, onions, berries, olive oil, cocoa, green tea
Feed beneficial gut bacteria linked to emotional resilience.
This is where nutrition becomes therapeutic — not just “healthy eating”.
What Research Shows: Food Really Does Affect Mood
One of the most important studies in nutritional psychiatry, the SMILES Trial, showed that a Mediterranean-style diet significantly reduced depression symptoms.
No calorie obsession.
No extreme restriction.
Just:
✔️ Whole foods
✔️ Olive oil
✔️ Fish
✔️ Vegetables
✔️ Legumes
✔️ Nuts
✔️ Fibre
✔️ Colour
In clinic, I see this constantly.
When clients eat for gut health, mood follows.
Your Nervous System Matters Just as Much as Your Diet
Your gut listens to your stress levels.
Busy. Rushed. Overloaded.
Always “on”.
Never resting.
That damages digestion.
At FIT, we work on calming the vagus nerve — your body’s “rest and repair” switch.
Simple tools that work:
Slow breathing (4–6 breaths per minute)
Gentle yoga or meditation
Cold face splash or cool shower finish
Singing or humming
Daily walking
Mindful eating
Small habits. Huge biological impact.
How We Support Clients at FIT Nutrition & Testing Clinic
When we combine:
✔️ Personalised testing
✔️ Guided elimination
✔️ Gut repair nutrition
✔️ Mood-support nutrients
✔️ Stress regulation
✔️ Supported reintroduction
We don’t just improve digestion.
We transform:
Energy
Confidence
Focus
Emotional stability
Relationship with food
Self-trust
This is why my approach works long-term — not just for 6 weeks.
Frequently Asked Questions About Gut Health & Mental Wellbeing
How does gut health affect mental health?
Your gut produces neurotransmitters and sends signals to your brain via nerves and immune pathways. Imbalances can contribute to anxiety, low mood and fatigue.
Can food intolerances affect mood?
Yes. IgG food reactions can increase inflammation and disrupt gut bacteria, influencing serotonin and stress chemistry.
What is the gut–brain axis?
It’s the two-way communication system linking your digestive system, nervous system and immune system.
Can improving gut health reduce anxiety?
Research suggests that improving microbiome balance, reducing inflammation and supporting vagal tone may help regulate stress responses.
How long does it take to heal the gut?
Most clients notice meaningful improvements within 4–12 weeks when following a personalised programme.
My Honest Message to You
I’ve watched hundreds of people walk into my clinic thinking:
“Maybe this is just how life is now.”
And walk out months later saying:
“I didn’t realise how bad I felt… until I felt good again.”
Your gut isn’t meant to be noisy.
Your mood isn’t meant to feel heavy.
Your energy isn’t meant to come from caffeine.
You deserve:
Calm digestion
Clear thinking
Stable moods
Confidence in your body
And it starts in your gut.
Don’t forget to pin it
Ready to Calm Your Gut & Lift Your Mood?
If you’re struggling with digestion, mood, anxiety, fatigue or brain fog — and you’re tired of guessing — I’d love to support you.
Take the quiz or book your FREE health review.
About Becki Hawkins
Becki Hawkins, BSc (Hons), mBANT, CNHC, is the founder of FIT Nutrition & Testing Clinic and a Registered Nutritional Therapist with over 20 years of experience. She specialises in evidence-based personalised nutrition and functional testing, helping clients uncover the root causes of digestive issues, hormonal imbalances, and unexplained symptoms. Becki combines clinical expertise with culinary creativity, translating complex test results into practical, delicious nutrition plans that work in real life. Her approach is simple: test, don't guess. Because guessing doesn't heal. Knowing does.