What is the gut-brain axis?

The brain and digestive tract are always communicating to help control eating, digestion, and other behaviours.

Experts believe that the vagus nerve connects the central nervous system (CNS – made up of the brain and spinal cord) and the enteric nervous system (ENS – layers of nerve cells lining your digestive system from your oesophagus to your rectum), so they can send signals to each other.

This network is an effective alarm system between the brain and the gut. For example, it helps us know whether we’ve eaten the wrong thing or are experiencing a highly stressful event, controlling the digestive system to react accordingly.

Why does it matter?

The gastrointestinal system is very sensitive to emotion and stress. This may be because it is a controlled part of the body’s fight-or-flight response, which can affect digestion – needing the toilet is not a priority when a perceived threat is looming. This means that experiencing constant high levels of stress can have a long-lasting effect on the digestive system, causing issues such as IBS or functional bowel problems, including constipation or diarrhoea.

It has also been suggested that the digestive system may contribute to changes in mental health and mood. Studies have indicated that patients with functional gastrointestinal disorders are likely to develop mental health issues such as depression or anxiety.

There is evidence that the gut microbiome (healthy bacteria in the gut) also influences the brain, in addition to the nervous system connection.

“More and more research is revealing that the gut microbiome can influence the brain and behaviour across a variety of different animals,” says Elaine Hsiao, associate professor in integrative biology and physiology at the University of California, Los Angeles (UCLA)[1].

Gut microbiomes produce neurotransmitters (chemical messengers to the brain) that the brain uses to regulate physiological functions. These chemicals also help regulate mental processes such as learning, memory, and mood. Inflammation or an unbalanced microbiome can send signals to the brain, causing an issue with mood regulation and leading to feelings such as anxiety or depression.

Symptoms and conditions

If somebody is experiencing gut-brain disconnection, they may experience symptoms such as:

• Bloating
• Indigestion
• Feeling something is stuck in the throat
• Regurgitation
• Constipation
• Diarrhoea
• Abdominal pain
• Incontinence

Conditions that might be affected by the gut-brain axis include functional dyspepsia and dysphagia, gastroparesis, chronic stress/fatigue/pain, obesity, neurodevelopmental disorders (e.g. autism), neurodegenerative disorders (e.g. Parkinson’s disease), and nerve-related pain disorders (e.g. multiple sclerosis).

Looking after your gut-brain axis

Diet has the most significant impact on the gut microbiome, so taking the necessary steps to improve your diet may improve your mood.

There are a range of foods and drinks that can improve gut health, including:

• Green tea
• Yogurt with live active cultures
• Almonds
• Miso
• Kefir
• Leafy greens, such as spinach and kale
• Lean protein
• Avocado

It is important to talk to a dietician about implementing these changes into your diet healthily, particularly if you experience gastrointestinal issues. At Digestive Health UK, we work with expert dieticians who can provide evidence-based nutritional advice tailored to your condition or issue.

Taking supplements such as pre- or probiotics can also help grow a variety of good bacteria and create a healthier gut microbiome.

Managing your stress and mental health also significantly impacts your gut health. Some things you can do to help manage stress include yoga, meditation, physical activity, being outside, therapy, or getting a good sleep routine. Also, complementary therapies in the form of acupuncture and/or gut-directed hypnotherapy can help improve gut symptoms for many patients.

Although there is still so much to learn, there are promising steps forward toward finding treatment and further connections between the brain and the digestive system.

If you are looking to investigate the cause of your digestive problems and learn more about your condition, book an appointment with us today. Our expert gastroenterologist will thoroughly assess your health to determine the most suitable treatment for you.

We also offer a second opinion service if you would like another assessment.

[1] https://www.bbc.com/future/article/20230120-how-gut-bacteria-are-controlling-your-brain