How the Gut Influence Brain Health


Did you know that you can influence brain health via the gut? 

The nervous system is predominantly associated with the brain, as well as the spinal cord and nerves. But scientists have also identified a nervous system within the lining of the gut – and this “second brain” directly communicates with the brain in the head. 

Consider the impact that feelings can have on your body – especially your gut: “butterflies” in your stomach when you are nervous, and how your stomach feels and responds when you are excited, fearful, angry, upset, and even joyful or newly in love. Have you noticed how certain strong emotions may make you lose your appetite, feel nauseous, or even vomit or have diarrhoea? 

These are examples of the gut reacting to signals from the brain. 

Likewise, the brain also reacts to signals from the gut.

This connection is known as the gut-brain axis. And it has enormous implications for your mental and emotional well-being.

What is the Gut-Brain Axis?

The gut-brain axis is the direct relationship between the brain and the trillions of microorganisms that live in the lining of the gut (i.e. the microbiome), particularly in the intestines. It profoundly affects the way the nervous system functions as well as mental health and resilience. 

The gut and brain are connected via:

  1. The vagus nerve modulates the brain-gut axis and helps regulate digestion, heart rate, respiratory rate, constriction and dilation of blood vessels, and reflex actions including sneezing, coughing, swallowing, vomiting, and more. The vagus nerve is the gut’s direct Physical connection to the brain. (The vagus nerve is also responsible for the nausea some people experience when they have a headache or migraine).

2. Chemicals including hormones and neurotransmitters send messages between the brain and the gut – and vice versa. 

The Gut consists of the:

  • Oesophagus
  • Stomach
  • Small Intestine
  • Large Intestine
  • and the Liver, Gallbladder, and Pancreas.

The lining of the gut is known as the “second brain”. This is because the human gut contains almost 500 million neurons, which connect to the brain via nerves. Stress and emotional upheaval harm the vagus nerve and are strongly associated with the development of gastrointestinal disorders.

A Symbiotic Relationship…

The gut produces 90% of serotonin (the “happy” hormone), 50% of dopamine (the “pleasure-seeking” hormone), as well as oxytocin (the “love” hormone) and melatonin (the “sleep” hormone). 

The hormones and neurotransmitters created by and which influence the brain are directly impacted by the gut microbiome. This is the colony of microscopic bacteria, fungi, and viruses that live in the gut. The microbiome is a delicate balance and, if this healthy balance is disrupted or the gut-brain axis is out of sync, illness, disease, and other negative impacts can occur.

A disturbed or disrupted gut-brain axis may, for example:

  • Cause inflammation of the brain that can lead to the development of stroke, multiple sclerosis, Parkinson’s disease, and Alzheimer’s disease. 
  • Promote weight gain by changing metabolism, eating behaviours, satiety control, and creating sugar cravings.
  • Negatively influence both mood and behaviour.

The Gut and Mental Health

Medical scientists have identified a very strong relationship between mental health conditions and gastrointestinal problems. A lot of people who suffer from chronic stress, depression, and/or anxiety also experience a higher-than-average incidence of symptoms including indigestion, heartburn, appetite loss or overeating, gastroesophageal reflux, pain, bloating, cramping, gas, constipation, and/or diarrhoea. The symptoms of irritable bowel syndrome (IBS) are more common and more pronounced in people with diagnosed mental health conditions or who are under high levels of chronic stress. 

Researchers have also discovered that an unbalanced gut microbiome or gut inflammation can cause certain symptoms that mimic other issues including depression, anxiety, and even autism, ADHD, and Parkinson’s disease.

Conversely, experiencing mental health issues such as depression and anxiety can alter the microbiome in the gut due to the body’s natural stress response. 

Healthy Gut, Healthy Mind

Supporting a healthy gut will also support a healthy mind – and vice versa. 

You can help achieve this by:

  1. Maintaining a healthy diet – plenty of vegetables, fruits, lean meats, whole grains, and healthy fats (e.g., nuts, avocadoes, fatty fish, olive oil). Omega -3 fatty acids found in fish oils directly benefit gut health (as well as that of the heart and metabolism).

2. Minimise or avoid eating processed, fried, sugary, or salty foods.

3. Moderate alcohol.

4. Don’t smoke.

5. Consume prebiotic foods – these are high in healthy fibre and help by feeding the good microorganisms in the gut. Prebiotic foods include just-ripe bananas, onions, garlic, asparagus, mangoes, apples, tomatoes, and berries.

6. Consume probiotics. These are colonies of live, good bacteria that exist in some foods and are also available in supplement form. They help build and support a healthy microbiome. Find probiotics in foods including yoghurt with live, active cultures, apple cider vinegar, kefir, miso, tempeh, kimchi and sauerkraut (unpasteurised), and kombucha.

7. Only take antibiotics for a confirmed bacterial infection or when otherwise completely necessary (e.g., before or after surgery). Antibiotics are ineffective for viral infections. They do kill the bacteria that cause diseases, but they also kill good bacteria and can wreak havoc on your gut microbiome. This is why a lot of people get symptoms of an upset stomach, diarrhoea, and thrush infections during or just after a course of antibiotics. Many doctors will recommend taking probiotics with antibiotics.

Final Thought

Looking after your gut is a critical first step to supporting your mental health and emotional well-being. A strong microbiome is the foundation of a healthy body, a robust immune system, and a resilient mind. 



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