Happy Hormones & the Gut-Brain Connection
- Julie Smullen
- Jul 25
- 6 min read
Understanding Oxytocin, Dopamine, Serotonin & Endorphins from a Holistic Perspective
Writer: Julie Smullen | Functional Nutrition Consultant, Certified GAPS Practitioner, Certified GAPS Coach & SmartDNA Practitioner.
This article is for educational purposes only and does not constitute medical advice
If you’ve ever been told your mental health struggles are simply the result of a “chemical imbalance in the brain,” you’re not alone. That theory was once the foundation of mainstream psychiatry, but it has since been largely debunked.
Current scientific research no longer supports the idea that anxiety, depression, or mood disorders are caused by a simple neurotransmitter deficiency.
Instead, we now know that mental health is deeply influenced by the health of your gut, your nervous system, inflammation levels, nutrient status, stress response, trauma history and environmental inputs.
From a holistic and functional perspective, emotional wellbeing is about restoring balance across multiple body systems not just taking a pill to “boost serotonin.”
In fact, most of your brain chemicals including serotonin, dopamine, and GABA, are either made in the gut or regulated by it. That’s why the GAPS Nutritional Protocol (Gut and Psychology Syndrome) is so effective at addressing mental health from the ground up. It’s not just about food, it’s about healing the gut-brain axis, calming inflammation, restoring digestion, and creating the environment for your happy hormones to function naturally.
Let’s explore the four major mood-supporting chemicals - oxytocin, dopamine, serotonin, and endorphins and how you can support them through gut health, lifestyle, and holistic nourishment.
Oxytocin - The Love & Connection Hormone
Oxytocin is your bonding hormone. It helps you feel emotionally connected, safe, affectionate, and loving. It’s released during hugging, cuddling, breastfeeding, eye contact, and even through petting animals or meaningful conversation. When oxytocin is flowing, we feel supported and calm in relationships.
Oxytocin isn’t made in the gut, but it’s heavily influenced by gut health. Chronic inflammation, trauma, or dysbiosis can keep the nervous system stuck in “fight-or-flight,” which blocks oxytocin signaling. I often see this in GAPS clients, especially children or adults with sensory issues, who gradually begin to seek more connection and touch as their gut heals and their nervous system calms.
Support oxytocin with:
Cuddling and physical affection
Playing with pets
Deep connection with loved ones
Warm meals and shared mealtimes
Massage, skin-to-skin contact, and co-regulation
Dopamine - The Motivation & Reward Hormone
Dopamine gives us energy, focus, and that rewarding feeling when we complete a task or achieve a goal. It helps us feel accomplished, alert, and driven. Low dopamine can lead to procrastination, brain fog, emotional flatness, and a lack of motivation.
Dopamine is made from protein-rich foods, but only if your digestion is strong enough to break them down. If your gut is inflamed or your stomach acid is low (which is extremely common), your body may not be absorbing the amino acids needed to make dopamine. Gut microbes also influence how dopamine is metabolised and whether your brain can actually use it.
On the GAPS protocol, we address this at the root. By healing the gut lining, restoring stomach acid, and feeding the body with nutrient-dense, healing foods like meat stock, eggs, and probiotic
ferments, we create the conditions needed for dopamine production to recover.
Support dopamine with:
Completing small tasks and celebrating them
Eating high-quality protein (eggs, meat, meat stock)
Doing things that give you purpose
Limiting sugar and social media binges
Mindful goal-setting and self-care routines
Serotonin - The Mood Stabiliser
Serotonin is often referred to as the “happy hormone,” but it’s actually more about emotional stability, sleep regulation, and resilience. Serotonin supports gut motility (yes, pooping!), appetite control, and a calm, steady mood. Interestingly, about 90–95% of serotonin is produced in your gut, not your brain.
Your body needs the amino acid tryptophan, along with nutrients like B6, zinc, magnesium, and iron to make serotonin. But if your gut lining is damaged or you’re not digesting properly, that whole process breaks down. On top of that, inflammation and leaky gut directly interfere with your ability to produce or utilise serotonin.
GAPS provides the framework to restore these systems, from healing the lining of the gut to restoring beneficial bacteria that support tryptophan metabolism. Once these pieces fall into place, it’s common to see mood swings ease, sleep improve, and overall emotional balance return.
Support serotonin with:
Morning sunlight
Walking in nature or grounding barefoot
Fermented foods (sauerkraut, kefir, yoghurt if tolerated)
B6-rich foods like liver and egg yolks
Gentle routines that create safety and calm
Endorphins - The Body’s Natural Painkillers
Endorphins are your inner pharmacy. They reduce pain, buffer stress, and help us experience joy and relief. We produce endorphins during laughter, exercise, deep breathing, music, and acts of kindness. If your endorphin levels are low, life can feel dull, heavy, or emotionally numbing.
Chronic gut inflammation, unresolved stress, and poor detoxification can all suppress your body’s natural ability to make and release endorphins. That’s why a big part of healing on GAPS involves not just the food, but also rebuilding joy and sensory nourishment, things like warm baths, dance, safe connection, and laughter.
Support endorphins with:
Laughing with others or watching something funny
Listening to music you love
Dancing, stretching, or moving your body
Taking detox baths (like Epsom salts)
Doing something kind or generous each day
Mental Health Is Not a Chemical Imbalance - It’s a Whole-Body Issue!
We now know that the idea of depression or anxiety being caused solely by a chemical imbalance is outdated and not supported by modern science. Mental health is multi-dimensional, involving your gut, immune system, nervous system, liver, hormones, trauma history, and daily environment.
From a holistic perspective, this means true healing must address the whole person. We don’t just want to manage symptoms, we want to rebuild the foundation for emotional wellbeing by supporting the gut-brain axis, calming inflammation, improving nutrient absorption, and nourishing the nervous system.
GAPS is one of the most powerful tools we have for this process. And when combined with personalised insights, like SmartDNA testing, which can reveal how your body uniquely processes neurotransmitters, nutrients, and detox pathways, we gain even deeper clarity on how to support your healing.
Ready to Restore Your Emotional Balance?
If you’re feeling stuck in cycles of anxiety, low mood, or burnout, please know, your body is not broken. It may simply need the right support to restore the systems that regulate your emotions.
I’d love to help you begin that journey.
Together, we’ll create a personalised plan to bring you back to balance, from the inside out.
Disclaimer: This blog is intended for informational and educational purposes only. It does not provide medical advice, diagnosis, or treatment. Supplements should be used responsibly and under the guidance of a qualified health professional. Always consult your healthcare provider before starting any new supplement or health program.
References
Moncrieff, J., Cohen, D., & Jacobs, N. (2022). The serotonin theory of depression: a systematic umbrella review of the evidence. Molecular Psychiatry, 27(10), 2193–2201. https://doi.org/10.1038/s41380-022-01661-0
Shows there's no consistent evidence supporting serotonin imbalance as the cause of depression.
Cryan, J. F., & Dinan, T. G. (2012). Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience, 13(10), 701–712. https://doi.org/10.1038/nrn3346
Foundational work connecting gut health and mental health.
Dash, S., Clarke, G., Berk, M., & Jacka, F. N. (2015). The gut microbiome and diet in psychiatry: focus on depression. Current Opinion in Psychiatry, 28(1), 1–6. https://doi.org/10.1097/YCO.0000000000000117
Highlights dietary and microbiome factors in mental health.
Genuis, S. J., & Bouchard, T. P. (2012). Celiac disease presenting as autism. Journal of Child Neurology, 27(6), 704–707. https://doi.org/10.1177/0883073811427202
Shows how gut and immune dysfunction can impact neurological development.
SmartDNA. (2023). Clinical DNA Nutrigenomics Report – Practitioner Overview. Retrieved from: https://www.smartdna.com.au
Tool used in clinical practice to investigate key gene variants affecting detoxification, mood, inflammation, and more.
Campbell-McBride, N. (2010). Gut and Psychology Syndrome: Natural Treatment for Autism, ADHD, Dyslexia, Dyspraxia, Depression and Schizophrenia. Medinform Publishing.
The foundational GAPS text explaining how gut healing restores neurological function.
Dinan, T. G., & Cryan, J. F. (2017). The microbiome–gut–brain axis in health and disease. Gastroenterology Clinics of North America, 46(1), 77–89. https://doi.org/10.1016/j.gtc.2016.09.007
Further explores how microbial health impacts mood and cognition.
Young, S. N. (2007). How to increase serotonin in the human brain without drugs. Journal of Psychiatry & Neuroscience, 32(6), 394–399. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2077351/
Details natural methods for supporting serotonin, such as diet and lifestyle.
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