What is the Gut-brain Axis?
In recent years, scientists have discovered a remarkable link between your gut and your brain - a connection known as the gut-brain axis. This two-way communication system plays a vital role in how we think, feel and function, influencing everything from digestion and immunity to mood and mental wellbeing.
In this article, we’ll explore what the gut-brain axis is, how it works and what it means for your overall health.
Whether you're managing digestive symptoms, dealing with stress or simply curious about your body's inner workings, understanding the gut-brain axis could help you take a more proactive approach to your physical and mental wellbeing.
Understanding the gut-brain axis
The gut-brain axis is the two-way communication system between your brain and your gut. They constantly share information through:
-
Nerve signals (especially the vagus nerve)
-
Hormones
-
Immune system messages
-
Gut bacteria (the trillions of microbes in your gut)
This means your gut can influence your mood and brain function just as much as your brain can affect your digestion.
How does the gut communicate with the brain?
The gut has often been described as the body’s "second brain" - and for good reason. The enteric nervous system (ENS) contains around 500 million neurons, and it works largely independently to manage digestion and gut motility. But it also sends signals to the brain, helping to regulate mood, behaviour and stress responses.
Some of the key ways the gut and brain communicate include:
-
Vagus nerve signals: This long nerve runs from the brainstem to the abdomen and acts as a primary communication channel between the brain and the gut.
-
Neurotransmitters: Many neurotransmitters that affect mood, such as serotonin and dopamine, are either produced or regulated in the gut.
-
Immune cells and cytokines: These can travel through the bloodstream, affecting both gut inflammation and brain function.
-
Gut microbiota: Although serotonin from the gut doesn’t cross the blood-brain barrier, it still affects mood indirectly. Gut microbes produce compounds like short-chain fatty acids that influence brain function and behaviour through the gut-brain axis.
What role do gut bacteria play in brain health?
One of the most exciting discoveries in recent years is the role of gut microbiota in shaping how we think and feel. The balance of bacteria in your digestive tract can impact:
-
Mental health: An imbalance of gut bacteria (dysbiosis) has been linked with anxiety, depression and even neurodegenerative conditions like Parkinson’s and Alzheimer’s.
-
Immune function: Around 70% of your immune system resides in the gut, and the microbiota help regulate immune responses.
-
Cognition and memory: Some studies suggest that healthy gut bacteria can enhance cognitive function and protect against cognitive decline.
-
Stress resilience: The gut microbiome can influence the hypothalamic-pituitary-adrenal (HPA) axis, which controls how we respond to stress.
Signs your gut-brain axis may be out of balance
Because the gut-brain axis influences such a wide range of bodily systems, problems with this communication channel can show up in many different ways.
Common signs of gut-brain imbalance may include:
-
Persistent digestive issues (bloating, constipation, diarrhoea, IBS-like symptoms)
-
Low mood, anxiety or frequent mood swings
-
Fatigue or poor sleep
-
Brain fog or difficulty concentrating
-
Frequent colds or infections (linked to immune system disruption)
-
Food intolerances or sensitivities
If you notice a combination of digestive and mental wellbeing symptoms, it may be worth exploring how your gut health could be playing a role.
What causes disruption in the gut-brain axis?
Several factors can interfere with the healthy communication between your gut and brain. These include:
Poor diet: A diet high in processed foods, sugar and saturated fat can promote inflammation and disrupt the balance of your gut bacteria.
Stress: Chronic stress can affect the nervous system and gut motility, leading to digestive issues. It can also alter the composition of your gut microbiome.
Lack of sleep: Sleep and gut health are closely linked. Disrupted sleep patterns can throw off your gut bacteria, which in turn may affect your mental clarity and mood.
Antibiotic use: While often essential, antibiotics can wipe out beneficial gut bacteria, which may take time to recover.
Lack of physical activity: Regular exercise has been shown to promote microbial diversity in the gut and support a healthier gut-brain connection.
How to support a healthy gut-brain axis
The good news is that small lifestyle changes can help support your gut health, and by extension, your brain health too.
Eat more fibre-rich foods A diet rich in prebiotics (non-digestible fibres that feed your good gut bacteria) can help promote microbial diversity. Good sources include garlic, onions, leeks, asparagus, bananas and whole grains.
Add fermented foods Fermented foods like yoghurt, kefir, kimchi, sauerkraut and kombucha contain probiotics - live bacteria that can support a healthy gut. These options are becoming more common in UK supermarkets and can help boost the balance of good bacteria in your digestive system.
Manage stress Practices such as mindfulness, meditation, yoga and deep breathing exercises can help regulate the stress response and improve gut function.
Exercise regularly Just 30 minutes of moderate activity a day can promote a healthy gut microbiome and improve both mood and digestion.
Get enough sleep Aim for 7–9 hours of quality sleep per night to allow your gut and brain to rest and reset. Consider a gut health check
If you're unsure how your digestive health may be impacting your wellbeing, a gut health test can provide valuable insights.
How Bluecrest Wellness can help
At Bluecrest Wellness, our comprehensive Health MOTs include a range of blood and health tests designed to give you a detailed understanding of your overall health, including digestive function, inflammation markers and more.
If you’re concerned about symptoms that may relate to your gut-brain axis, such as fatigue, stress or digestive issues, we can help you identify potential imbalances early. Every full health assessment includes:
-
Convenient, fast appointment at a local clinic
-
Expert analysis and an easy-to-read Results Report
-
Free 24/7 GP helpline for a year
-
Tailored advice on next steps
By proactively checking in on your health, you can take meaningful steps to support your body and mind, starting with the gut.
