The gut-brain connection:

How gut health impacts your mood.


For a long period of time, scientists have gone along with the theory that mental illness and mood imbalances are linked to a chemical imbalance in the brain. Often this is addressed with antidepressant medication. Unfortunately, antidepressant drugs quite often come with side-effects, such as:

  • low libido
  • weight gain
  • loss of, or increased appetite
  • sleep disturbances
  • digestive disturbances
  • joint pain
  • poorer emotional outcome, such as suicidal thoughts
  • nutrient depletions such as B vitamins (particularly folate), magnesium, CoQ10


Nobody wants to go through their day forcing every move, feeling like they don’t have the mental capacity to carry out their day, or like they aren’t good enough. Mental illness, of any severity, can be debilitating and can change your life. And everyone wants to be able to feel their best.


Luckily, there are ways that we can improve mood naturally.


With or without genetic influences, mental illness doesn’t have to be a life sentence.


Studies are now beginning to debunk the ‘brain-chemical imbalance’ theory, and more research is linking gut health and inflammation to mental health.


Even when there is a chemical imbalance, (neurotransmitter excess or deficiency) there is always an underlying cause. These imbalances in the brain do not just happen.


Mood disturbances are driven by other imbalances in the body. Addressing the underlying cause, as is a naturopathic philosophy, is the way to improve mood and mood-related disorders and result in a longer term solution, rather than having to depend on medication and ‘put up with’ side effects just to feel like a functional human being.



What does gut health have to do with mood?


You might know what it’s like to get a bit of a stomach ache when you get nervous or stressed, but the impact that the brain has on the gut, and vice-versa, goes much deeper than this. Naturopaths have long held the theory that all illness starts in the gut. 70% of our immune system is found in the gut. It is an important population of microbes which can communicate with all parts of the body, especially the nervous system.


In recent years, this has been termed the gut-brain-axis (GBA).


The gut can communicate with the brain, and vice-versa, by means of hormonal, neural, and immune mechanisms. The gut and brain are connected directly via the vagus nerve.


Microbes that inhabit the gut can stimulate and influence the vagus nerve, mediating the effects of mood and behaviour. This can be done by stimulating the release of inflammatory or anti-inflammatory mediators and certain neurotransmitters, resulting in beneficial or disadvantageous outcomes.



Leaky gut


The gut has a semi-permeable barrier, which in a healthy state, can allow beneficial nutrients and other substances into the bloodstream to reach other parts of the body, and also prevent undesirable substances from getting through, such as waste products, pathogenic bacteria and endotoxins.

Leaky gut, also termed intestinal hyperpermeability, is when this process is compromised, leaving the potential for unwanted substances escaping the gut and entering systemic circulation. This can trigger inflammation, immune dysregulation and other issues in various locations, including the brain. Leaky gut can be found at the core of many health complaints, including:

  • mood and behavioural disturbances
  • digestive complaints such as bloating, malabsorption of nutrients and constipation
  • fatigue
  • ‘brain fog’, poor memory and poor concentration
  • autoimmune diseases such as Hashimoto’s thyroiditis, type 1 diabetes and Crohn’s disease.


I talk a little bit more about leaky gut and what causes it in this blog post.



Nutrient deficiencies related to poor gut health


The small intestines assist in synthesising many important nutrients. For example, beneficial bacteria use dietary fibre to synthesize short-chained fatty acids (SCFA). Some bacteria consist of important enzymes needed to synthesize nutrients such as some proteins and B vitamins (especially B12). An estimated half of our daily intake of vitamin K, involved in bone and cardiovascular health and calcium and vitamin D metabolism and absorption, is also synthesized by our gut bacteria.


Now that the link between gut and mood makes a little more sense (I hope!)… What can we do to address it?


This will differ from person-to-person and can be quite complex. Addressing the underlying issue(s) can require some further investigation. However, there are some simple things you can do to improve the way you feel every day. And yes, a lot of it does come down to the way you look after your body.



Stay tuned for my next post, which covers some important things you can do in order to improve your mood. To be notified when it’s up and ready for you read, you can sign up to my newsletter to get the latest updates!

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