Is Gut Health The Key To Better Mental Health And Wellbeing?

Mental Health

Tammy George

A lady preparing fresh vegetables to maintain overall health and wellbeing

The latest research shows a clear link between gut health and overall health, including your mental health. Scientists refer to the connection between your gut and your brain as the “gut-brain axis” and they are finding more and more evidence for a connection between gut bacteria and issues such as anxiety and depression.

What is Gut Health and Why is it Important?

Good gut health means having a healthy balance of gut microbiota with sufficient beneficial bacteria in your gut. Gut microbiota is the name scientists use for the microbes living in your intestine - there are over 100 trillion microbial cells in your gut. They contribute to food digestion, metabolism, the immune system (protecting the body from other microorganisms) and can have an impact on mental health, mood, weight and digestive disorders.

Poor gut health and digestive disorders have symptoms that include one or more of the following:

  • Diarrhoea

  • Constipation

  • Gas and bloating

  • Acid reflux

  • Obesity & weight gain

  • Foul smelling faeces

  • Skin problems

  • Bad breath

  • Poor mood

  • Poor immune system (getting sick more often than normal)

What is Microbiota?

Microbiota was previously referred to as gut flora and is the microbe population that lives in our intestines. The trillions of microorganisms are made up of 1000 different species of bacteria, fungi, yeasts, viruses and protozoans which weigh 2kg, heavier than the average brain. The ecosystem contains about 3 million genes and is treated by scientists as an organ.

Most people’s microbiota is one-third common to most people and two thirds specific to the individual. Microbiota resides in the intestine and colonisation begins after a baby is born.

Microbiota is responsible for a range of different functions to keep us healthy including:

  • Digesting some foods that weren’t completely digested in the stomach or small intestine

  • Combating aggression from other microorganisms

  • Helping with the production of vitamins B and K, and

  • Assisting the immune system by providing a barrier against viruses

  • Killing cancer-forming carcinogens

  • Sending messages to the brain to control metabolism

Gut Health and Mental Health

Known as the ‘gut-brain axis’, the axis facilitates a bi-directional link and communication between the brain and gut. The vagus nerve carries much of the communication between the two functions. Signals are transmitted from the liminal environment to the central nervous system which can alter brain function.

A lady suffering from a stomach ache due to poor gut health

The Link Between Gut Health, Depression & Anxiety

For decades, doctors have thought that depression was due in part to the genes we were given but, with recent research showing a link between gut health and depression, there is now hope that we can have more influence on depression by addressing gut health.

Other research has shown a possible connection between gut bacteria and anxiety. A recent study found that the brains of mice which were missing good gut bacteria didn’t function normally in regions that are linked to anxiety and depression.

Another study found that anxiety levels in mice were reduced when a strain of “good bacteria” was added to their gut. To make it even more interesting - when the vagus nerve (connecting the brain and gut) was blocked, the anxiety-reducing effect could not be observed. This indicates there could be a connection between the gut, brain and anxiety.

Mood altering bacteria in the gut has been dubbed ‘psychobiotics’ by a neuroscientist. While we can’t alter the genes our parents passed on to us, we can alter our microbiome largely through diet. Our microbiome has one hundred times more genes than the human genome we inherited.

Studies have linked gut microbiota with people suffering post-traumatic stress disorder (PTSD). People with PTSD have lower than normal levels of gut bacteria.   

Research Linking Gut Health and Autism

Research has shown there is a strong link between gut bacteria altering the biochemistry of our brain. A study in 2013 showed that mice with features of autism had much lower levels of a gut bacterium called Bacteroides fragilis than mice without autism. When the mice were fed the bacterium, their autism symptoms reversed. Many people living with autism now take a daily probiotic as part of their treatment. It is the reason why the gut is now being considered as the second brain.   

Scientists are hopeful that with more research, it will be possible to analyse gut microbiota to diagnose some brain diseases and mental health problems and treat them.

How to Test Your Own Gut Health

If you aren’t sure what condition your gut’s microbiota is in, you can take a test.

To understand how healthy or otherwise your gut is, you can take a Gastrointestinal Tract test.   Complete Digestive Stool Analysis (CDSA) can report on bacteriology, mycology (yeasts), parasitology, short-chain fatty acids, biochemical markers and sensitivities (bacteria/yeasts).

In-home microbiota tests also help analyse the nutrients and toxins being produced by the gut microbiome and recommend foods to improve gut health.

What’s The Best Diet for Gut Health?

The gut is no different to most parts of the human body, it relies on you eating a healthy diet to work optimally.

Foods that Improve Gut Health

By changing what you eat, you can change your gut’s microbiota in as little as 24 hours. Colourful, plant-based foods allow good bacteria to flourish. Foods high in fibre such as fruits, vegetables, whole grains, nuts and legumes are vital for a good gut health. Some foods have better properties than others.

An array of fresh healthy foods such as vegetables, whole grains and legumes.

Foods high in the soluble fibre Inulin have a strong prebiotic potential. Asparagus, leeks, onions and bananas travel to the colon and ferment into healthy flora.

Bananas are also excellent for harmonising the bacteria community and reducing inflammation due to their high levels of potassium and magnesium.

Broccoli, kale, cauliflower release substances that reduce inflammation and latch on to carcinogens in the colon, taking them out of the body.

Legumes help strengthen and feed the good gut bugs to regulate a healthy gut and improve the absorption of nutrients.  

Gut Health Supplements & Probiotics

Many people reach for probiotic supplements as soon as they have finished a course of antibiotics or feel that their gut isn’t as balanced as it should be. Some probiotic supplements are designed to improve skin conditions, for example, more than mental health.

Prebiotic foods feed the good bacteria in our gut so include non-digestible foods like bananas, onion, garlic, brussel sprouts and broccoli.     

Probiotics are live bacteria and yeasts that are good bacteria. Probiotics aren’t just available as supplements, they can also be consumed through food. Think fermented foods such as sauerkraut, miso, kimchi and yoghurt. These foods contain Lactobacillus and are ideal for people who can’t digest lactose in dairy products. Bifidobacterium is found in dairy products and can help with IBS symptoms.  

How to Improve Your Gut Health Naturally

Highly processed foods high in fat and sugar can have a harmful effect on your gut bacteria.

The best thing you can do for the health of your gut is to eliminate junk foods like soft drink, fruit juice, lollies, chips, fast food and biscuits and consume healthier, high fibre foods in their place.

When some gut bacteria are destroyed, your microbiota becomes less diverse and makes you more susceptible to some diseases.

Along with the foods and supplements available to improve gut health, there are also lifestyle changes you can make to improve your microbiota.

Cut Out Alcohol

Consuming alcohol can be a double whammy as it can cause mental problems and have a harmful effect on gut bacteria. But not all alcohol has the same impact. Red wine increases the abundance of good gut bacteria due to the polyphenol content when consumed in moderation. Spirits, however, decrease the number of beneficial gut bacteria so if you make the change from spirits to red wine you will be doing your gut a favour.  

Get Enough Sleep

Sleep deprivation has been linked to a range of health conditions. A 2016 study examined the effects of sleep deprivation on gut flora. After two nights of four hours sleep compared to two nights of 8.5 hours, there were subtle changes in gut flora that increased the bad bacteria.

Vary your Diet

By eating the same foods you aren’t exposing your body to a wide variety of bacteria. Different families of bacteria grow on different food types so eating a wide range of foods will expose your body to different bacteria. Aim for at least 30 different foods each week.   

Reduce the Fat in your Diet

Diet has an obvious impact on your intestinal flora and gut health. One study showed that converting a mice’s diet from low fat and low sugar to a high sugar and high-fat diet, the number of good bacteria declined rapidly.  

Reduce Stress

Try to limit the amount of stress in your life as it can impact on all parts of your digestive system including your microbiota. During a stressful time, your central nervous system can shut down blood flow and contractions in your digestive system. Inflammation of the gastrointestinal system can occur. The colon can also be impacted by high stress causing you to have diarrhoea or constipation.

A man meditating to reduce stress and maintain good digestive health

Monitor any Food Intolerances

A food intolerance is one of the causes of Irritable Bowel Syndrome (IBS), which affects up to 25% of the population. Multiple studies have confirmed that the intestinal flora of IBS sufferers is different from the flora of healthy people. Intestinal flora may affect the visceral sensitivity, inflammatory response and the gut-brain axis which leads to IBS.  


Some prescription and over-the-counter medications can cause everything from intestinal constipation, diarrhoea, a delay in emptying the stomach contents, and stomach irritation. If a new medication causes any kind of stomach upset, see your doctor.  

The medication that causes the biggest problem for your gut is antibiotics which can wipe out the good bacteria while it goes after the cause of an infection. 

Exercise Every Day

As well as a healthy diet, exercise is thought to encourage a variety of gut bacteria. The wide variety of bacteria makes for a varied gut microbiota which can reduce your risk of some disease and ailments.   

Treat Digestive Conditions

When digestive health is compromised, it can show in one of several digestive system conditions.

The most common digestive conditions include:

Diverticulitis – infection or inflammation of pouches in the lower large intestine.    

Stomach ulcers – ongoing, low level inflammation of the stomach caused by the bacteria Helicobacter pylori which causes ulcers in some people.

If you are suffering from a digestive problem, seek treatment from your doctor rather than learning to live with the discomfort. By not treating digestive conditions and living with the symptoms, you are not only doing harm to your digestive system but potentially your whole body including your brain.  

So, the evidence indicates that if you want to look after your mental health, look after your gut. Eat a varied balanced diet and restrict your fat and sugar intake. Get plenty of sleep, exercise and keep the stress levels down to maximise your gut’s healthy bacteria.

Tammy George

Please note: Tammy's blog is general advice only. For further information on this topic please consult your healthcare professional.

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