Gut health and mental health: what's the link?

Going with your gut

Ever faced a tough decision or struggled to figure out how you feel about something? Chances are you might have been advised to 'go with your gut'!

As it turns out, our gut may be even wiser - and more involved with the workings of our mind - than we thought.

The link between gut health and mental health forms the basis of an emerging field of research which is sparking a lot of interest in the scientific world. A lot of the research available is fairly new, but the number of studies seems to be increasing with each passing year.

Could it be that what we eat directly affects our state of mind? And what role does the gut have to play in all of this?

What do we mean by the 'gut'?

For lots of us, the term 'gut' is quite fuzzy, referring generally to your lower digestive tract where nutrients from food are absorbed.

However, when talking about the link between gut health and mental health, we need to consider another major stakeholder: your gut bacteria.

Your gut is home to about 100 trillion bacteria.(1) Their collective weight adds about four pounds of biomass to each person - which is more than the weight of our brains!

Some of these bacteria are really beneficial to our health, while others are less helpful. Generally speaking, the 'good' bacteria help to keep the 'bad bacteria in check by maintaining their populations at a healthy level. They live in a delicate balance which is, at least in part, dependent on the food you eat. All together, this fascinating ecosystem of bacteria is known as your gut microbiome.

What's more, your gut microbiome is as unique to you as your fingerprint. Even if you eat the same diet, your gut microbiome will be slightly different from that of other members of your family or your friends.

It performs so complex a role in our bodies that some scientists have even begun to refer to it as the 'third brain'.

Gut health and mental health

So, we know that the bacteria in our gut have a bigger role to play in our health and wellbeing than we realised. But how do they affect your mental health?

If you have ever suffered from difficulties with your mental health, you will know that stress is a major trigger for many disorders. Capable of setting off panic attacks, increasing anxiety and leading to depression, stress is a factor that many people have to manage daily to maintain their mental health.

Scientists have discovered that the gut microbiome plays a very important role in allowing us to manage stress normally.

Researchers looked at what happened when there are no microbes living in the gut. This helped them to understand exactly how the gut microbiome influences our lives.(1) They discovered that, without gut microbes, a process called 'myelination' does not happen as usual.

Myelin is a substance made up of protein and fatty substances which forms a layer around nerve fibres. It acts as insulation, preventing electrical signals from escaping and helping them to reach the right place. Without myelination, nerve signals stay isolated. Myelin also helps our brains to stay fluid and adaptable.(2)

Gut microbes seem to be instrumental in helping to form the genes that tell us how to create myelin.

A lack of myelin affects our response to anxiety and fear. It also slows down our learning and cognition. Stress becomes insurmountable. Together, all of these things are a major burden on what we think of as mental health, and the brain becomes less able to handle everyday obstacles. As a result, our mental and emotional resilience declines.

In short, we need myelin for our mental health, and we need our gut bacteria to make myelin.

Can you alter your gut microbiome?

As mentioned above, your gut microbiome is completely unique to you. However, unlike your fingerprint or your DNA, it's perfectly possible to alter your gut bacteria.

We know that a healthy diet is instrumental in creating and maintaining a gut microbiome. Lots of diversity in your diet, and plenty of fibre, help too. Avoiding taking unnecessary courses of antibiotics is sensible as well, as these medicines tend to wipe out a lot of the beneficial bacteria in your gut as well as eliminating the bad ones. It may take you some time to build your normal gut microbiome back up after a course of antibiotics.

If you're interested in changing your gut microbiome with a view to improving your mental health, there are certain types of food which may be especially helpful.

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Prebiotics, probiotics and psychobiotics

These three terms refer to groups of foods which may help your gut microbiome to stay healthy.

Prebiotics are not digestible by humans, but they can be fermented and broken down by your gut bacteria, which are then able to extract their valuable nutrients. Prebiotics include vegetables. like Jerusalem artichoke, tigernuts, asparagus, onions and garlic. Think of prebiotics as a little care package which reaches your gut bacteria intact and provides them with a nourishing meal.

Probiotics are foods which contain live bacteria. The idea is that these beneficial bacteria reach your gut and either increase the population of 'good' bacteria, or add another type of useful bacteria into the mix. Examples of probiotics include live yoghurt, sauerkraut, pickles and tempeh.

Want more ideas on which prebiotic and probiotic foods to add to your diet? Head over to our article on prebiotic and probiotic foods.

Meanwhile, 'psychobiotics' refers to live bacteria which, when eaten, are thought to have a positive impact on your mental health. However, it's important to note that research on psychobiotics is in its very early days. Psychobiotics don't (yet) constitute their own group of foods, but rather it's thought that some bacteria found in prebiotics and probiotics may act as psychobiotics. → View Related Products

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Gut health disorders and mental health disorders

Researchers have also observed links between gut disorders and mental health problems.

For example, more than a third of people suffering from Irritable Bowel Syndrome (IBS) also struggle with depression.(3) Another study looked at patients suffering from gastrointestinal disorders who were later referred to psychiatrists. More of these patients were diagnosed with psychotic disorders than patients who were referred directly to psychiatrists.(4)

Moreover, 36.5% of patients who have functional gastrointestinal disorders such as functional dyspepsia also have psychiatric disorders. These are often connected to panic or anxiety.(5)

Finally, 60% of patients suffering from acute, consistent constipation also exhibited mental or spectrum disorders.

In some cases, it could be that the symptoms of a gut disorder such as IBS may cause a depression or anxiety response as they can be distressing and disruptive to normal life. However, it's also possible that there may be a more causal link between gut health disorders and mental health issues.