Mental Health &
The Gut-Brain Axis
It can be really frustrating when you’re feeling anxious or down and you’re told, “Just eat something healthy and you’ll feel better” or “you just need to be healthier”.
Answers like these may feel overly simplistic and it might leave you wondering whether the person is truly listening to how you’re feeling.
It is important to have a good support network around you that knows what works for your mental health, but what if some of the suggestions you’re given about your diet are based on science?
Should you ignore those comments and go straight for the comfort food and easy snacks when you’re not feeling yourself? Well, it’s not that simple, so let’s unpack some of the science behind it.
One of the latest areas of interest in mental health research is the role of the gut-brain axis (GBA). Now, what is this?
The Gut-Brain Axis (GBA)
The GBA is a system in your body that allows the signals from your gut to reach and affect the processes in your brain and vice versa; in this way, it’s bidirectional (going both ways).
Usually, the GBA is a great communication method where your gastrointestinal system can communicate with your brain to ensure your body continues to function as normal and to correct itself when needed (Cryan et al., 2019).
The way this works is that signalling molecules (such as hormones, neurotransmitters or immune factors) are produced in your gut and signal to your brain what is happening. In a situation where your gut isn’t at its healthiest, the signalling molecules that are produced can actually affect the balance of neurotransmitters that play a role in mental health disorders, as shown below in Figure 1.
Poor diet or an illness such as irritable bowel syndrome (IBS) or Crohn’s disease is known to affect the health of your gut or the ‘microbiome’. This is the regular order of those hormones, neurotransmitters and immune factors in your gut that keep up the normal signalling to the rest of your body and brain. A poor diet over a long period of time is known to increase inflammation in the brain and this is shown in research from birth all the way to adulthood.
Mental Health Markers
One of the markers (or physical symptoms) for many common mental illnesses such as depression, anxiety or schizophrenia is inflammation in the brain. Inflammation is helpful when your body is protecting itself from an injury—such as swelling after twisting your ankle. However, long term or ‘chronic’ swelling can actually cause ‘oxidative stress’ (lack of oxygen to the cells in your brain). This oxidative stress can result in cell death or malfunction, and this process is known to create an increased risk of mental illness.
We know that a common marker for some mental illness is inflammation in the brain but there are also other symptoms that indicate gut involvement. This can be anything from an increase or loss of appetite in depression to stomach aches, or an increase or decrease in bowel movements in anxiety. This functional link as well as the inflammation in the brain further shows the relationship between these mental illnesses and what’s going on in your gastrointestinal system.
Mental Health & Diet
A standardised population study of around 70,000 people was conducted in the UK taking into account factors such as age, wealth and sex. In the study, they observed the diets of people with the most common mental illnesses, such as depression, bipolar and schizophrenia. The study found that they all consumed “significantly more carbohydrates, sugar, fat and saturated fat than the mentally healthy control population”.
We know that the intake of poor choices of food, which negatively affect your gut health or ‘microbiome’, can increase inflammation which then increases the chance of mental illness. However, according to the National Centre for Biotechnology Information, people that are already diagnosed are more likely to “make poor food choices and select foods that might actually contribute to depression”.
A recent study also observed the effect of a nutritionally balanced diet on mental illness patients and found these patients improved most when their diet changed, irrespective of whether they also received counselling and medication.
So, is this really a chicken-and-egg argument? Is a poor diet a factor that is causing our mental illness or do we crave foods that aren’t good for us when we’re not well?
Gut and mental health varies from person to person, and things that work for you might not work for others. However, it is important to know that diet does play a role in mental illness. Whether you’re eating too much or too little, or even normal amounts of poor-quality food, it’s important to keep this in mind. The research shows that a happy microbiome will put you in the best place for a happier you.
Promoting A Happy Microbiome
What can you do to help promote a healthy gut microbiome? Fermented foods are super popular, so drinking kombucha or indulging in some kimchi with your next rice bowl could go a long way. The best thing to do is to eat balanced meals that contain fewer carbohydrates, sugar, fat and saturated fat, and eat more wholefoods that promote optimal gut health.
However, a treat now and then isn’t going to affect your gut health. If something doesn’t feel right in your gut, it’s best to chat with your GP who can work out a plan that will suit your needs.
Healthy gut microbiota is shown to correlate with less inflammation in the brain, and common mental illnesses such as depression are often categorised by chronic, low-grade inflammation in the brain. Taking care of your diet and dietary health could have a positive impact on your mental health.
Kat Turner – Project & Volunteer Manager
Katherine ‘Kat’ Turner recently completed her Bachelor’s Degree in Health & Medical Sciences with a specialisation in Neurosciences with the University of Adelaide and an Honours degree in Neurosciences with the University of Adelaide and UniSA. She is now a part of the team here at Encounter Youth in a Project & Volunteer Manager role. Kat is passionate about the health of young people and how health education can be utilised to improve their everyday life.
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