The Gut-Brain Axis: How your gut influences mood, focus and mental clarity
Carissa Heath
Most people think of digestion and cognition as two separate jobs happening in two separate places. One is happening in the gut, one in the brain. However, your gut and your brain are in constant, two-way conversation and the language they speak is chemical, electrical, and microbial.
Scientists call this conversation the gut-brain axis: a communication network linking the trillions of microbes and hundreds of millions of neurons in your intestines to the central nervous system, via the vagus nerve.
Did you know?
The gut is sometimes nicknamed the "second brain" because it contains its own semi-independent nervous system (the enteric nervous system) made up of more than 100 million neurons. That's more neurons than you'll find in your spinal cord.
The gut is sometimes nicknamed the "second brain" because it contains its own semi-independent nervous system (the enteric nervous system) made up of more than 100 million neurons. That's more neurons than you'll find in your spinal cord.
The chemistry of the conversation.
A large share of your body's serotonin (80 – 90%), the neurotransmitter most associated with mood and calm isn't made in the brain at all. It's made in the gut, largely under the influence of gut bacteria. When the microbial environment shifts, serotonin levels shift with it. The same is true for dopamine your reward and motivation neurotransmitter.
The vagus nerve is the physical cable running the length of this relationship, carrying signals from gut to brain roughly ten times more often than from brain to gut. This is one reason a "gut feeling" is a physiological reality, not just a turn of phrase.
Short-chain fatty acids (SCFAs) metabolites your gut bacteria produce when they ferment prebiotic fibre, are a major part of the message being sent. Butyrate, the most extensively studied SCFA, is produced when beneficial bacteria ferment fibres, and researchers have specifically investigated butyrate's role in modulating the gut-brain axis, alongside its established role supporting the integrity of the gut lining and reducing inflammation.
The research.
A randomised, placebo-controlled human trial specifically studied a butyrate-generating supplement for its effects on the gut-brain axis, a sign of how seriously this connection is now being taken in clinical research, not just wellness commentary.
A randomised, placebo-controlled human trial specifically studied a butyrate-generating supplement for its effects on the gut-brain axis, a sign of how seriously this connection is now being taken in clinical research, not just wellness commentary.
Why an unsettled gut can mean an unsettled mind.
If digestion is uncomfortable, inflamed, or irregular, the enteric nervous system must work harder, and it doesn't do this work quietly. Discomfort, bloating and irregularity generate their own signals up the vagus nerve, which is part of why a rough gut day so often arrives with a foggy, flat, or irritable head day attached.
Studies on partially hydrolysed guar gum (PHGG), a well-studied prebiotic fibre, have specifically measured markers like salivary cortisol alongside gut microbiome changes, reflecting a broader research interest in whether feeding the right bacteria in the gut can influence the body's stress response pathways.
How Gut Restore is formulated with this connection in mind.
Gut Restore brings together ingredients chosen to support the gut environment that this axis depends on:
↳ Sunfiber® PHGG is a prebiotic fibre that feeds beneficial gut bacteria, supporting the fermentation process that produces SCFAs like butyrate.
↳ CoreBiome® Tributyrin is a source of butyrate itself, delivered via a tributyrin structure designed to survive the upper gut so more of it reaches the colon where it's needed.
↳ Bifidobacterium lactis HN019 is a clinically studied probiotic strain researched for its role in supporting healthy bowel function, with proposed mechanisms involving the gut-brain-microbiota relationship via serotonin signalling pathways.
↳ L-Glutamine is a conditionally essential amino acid that serves as a primary fuel source for the cells lining the gut, supporting the structural foundation the enteric nervous system sits within.
↳ Ginger Root and Fennel Seed Extract are traditionally used to support digestive comfort, helping settle the kind of gut discomfort that competes for your attention and clarity.
Practical takeaways.
↳ Feed your fibre-fermenting bacteria daily. SCFA production depends on regular substrate (fibre), not occasional effort.
↳ Notice the pattern: if foggy, flat days tend to follow bloated or irregular ones, your gut may be trying to tell you something.
↳ Consistency matters more than intensity. The gut-brain axis responds to sustained microbial and dietary habits, not one good week.
Researchers now describe the gut microbiome as functioning almost like an endocrine organ, producing signalling molecules that travel well beyond the digestive tract.
Supporting a healthy gut environment is one of the most evidence-backed, foundational ways to support how you think and feel day to day. It won't replace sleep, movement, or a good support network. However, it’s the foundation everything else stands on.
This article is provided for general educational and informational purposes only and does not constitute medical advice. It is not intended to diagnose, treat, cure, or prevent any disease. Switch Nutrition Gut Restore is a formulated supplementary sports food intended to support general digestive wellbeing as part of an appropriate diet and is not suitable for children under 15 years of age, or pregnant or lactating women. It should be used under medical or dietetic supervision in conjunction with an appropriate diet and, where relevant, a physical training program. If you have a health concern, please speak with your doctor, dietitian, or another qualified healthcare professional.