If you have been keeping up with the news lately you will have seen that there is strong evidence to suggest that your gut microbiome can influence your mood and potentially prevent depression. Sounds like something we can all benefit from by improving.
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So, what is your microbiome? The gut microbiome refers to the billions of bacteria and other microorganisms that colonise your digestive system (1). Not only are these bugs involved in the digestion of food, metabolism and immune function but they are also important in your mental health (1).
Our gut microbiome starts developing from birth, and is influenced by genetics, the environment, stress, medication and diet (1). Research has shown us that diet in particular can dramatically change our gut microbiota (1). A study involving a diet swap between Rural Africans and African Americans showed just this (2). Rural Africans predominantly eat a plant-based high fibre diet, while African Americans predominantly eat a highly processed low fibre diet. Within only two weeks of swapping diets there was a significant increase in markers of cancer risk found in the bowels of the rural Africans and a decreased risk found in the African Americans. However, once the study finished the microbiome returned to a healthy baseline, proving that you need to consistently eat a good diet to make lasting changes to your microbiome.
So now you are probably thinking, what does this all mean in relation to my mental health? Well did you know that our gut and brain are linked? They are linked via the gut-brain axis, which refers to the bi-directional connection between the gut and the brain.
You know when you are nervous before giving a big speech and you feel butterflies in your stomach? That is the gut brain axis in action. This highlights that what is happening in the gut can directly influence our brain function and behaviour. Dysbiosis in the microbiome, which refers to an imbalance of microbes within the microbiome has been found to directly influence the gut-brain axis’ normal functioning, resulting in mental health conditions such as depression and anxiety. Recently, a study transferred gut microbiota samples from persons with major depression and re-colonised them in healthy rats (3). Later, the rats went on to show behavioural changes related to depression, suggesting that gut microbiota may play a causal role in the development of features of depression (3).
So how can we alter our gut microbiome and improve our gut health? The best way to diversify your microbiome and improve your gut health is to eat a well-balanced diet including plenty of fibre, fresh fruit & vegetables and limit highly processed foods and alcohol (4). Probiotic and prebiotic foods are also crucial in our gut health (5). Probiotics refer to the live micro-organisms, or ‘gut bugs’, that live inside your gastrointestinal tract, hence by consuming probiotics you are helping to diversify your microbiome (5). Foods sources of probiotics include fermented foods such as greek yoghurt, kefir, kimchi, kombucha, miso and tempeh. Prebiotics act as a source of food for the probiotics, keeping our gut bugs active, happy and healthy (5). Foods sources of prebiotics include asparagus, legumes, green bananas, chicory, garlic and whole grains.
With large studies showing that those who eat a balanced diet have lower rates of mental illness, it may be of great importance to begin to prioritise our dietary intake on a daily basis (6,7). In saying this, research is still in its infancy and we need many more human studies before we can say with certainty how to best harness the microbiota in order to improve brain function and mental health.
To conclude, we know that optimising our microbiome is key to living a healthy life, both physically and mentally. By beginning with managing our daily nutritional habits we can make big steps towards achieving this.
What can I start doing today to improve my gut health?
- Eat 25g of fibre per day for females and 30g each day
Not sure what foods to eat to help you achieve this? Check out this resource http://www.nutritionaustralia.org/national/resource/fibre
- Diversify your intake. Don’t eat the same foods every week, your microbiome thrives off different foods. Consume plenty of different fruit, vegetables, grains, legumes as well as sources of probiotics and prebiotics.
- Limit processed foods such as processed meats, fried
foods, soft drink, lollies and chocolate.
Written by Accredited Practising Dietitian and Sports Dietitian Atlanta Miall
1. Bull MJ, Plummer NT. Part 1: The Human Gut Microbiome in Health and Disease. Integr Med (Encinitas). 2014 Dec; 13(6): 17–22.
2. O’Keefe SJD, et al. Fat, fibre and cancer risk in African Americans and Rural Africans. Nat. Commun. 2015 Apr; 6: 6342.
3. Kelly JR. Transferring the blues: Depression-associated gut microbiota induces neurobehavioural changes in the rat. J Psychiatr Res. 2016 Nov; 82:109-18.
4. Singh RK. Influence of diet on the gut microbiome and implications for human health. J Transl Med. 2017; 15: 73.
5. Pandey KR, Naik SR, Vakil, BV. 2015. Probiotics, prebiotics and synbiotics- a review. Journal of Food Science and Technology. Dec; 52(12): 7577–7587.
6. Jacka FN, Mykletun A, Berk M, Bjelland I, Tell GS. The association between habitual diet quality and the common mental disorders in community-dwelling adults: the Hordaland Health study. Psychosom Med. 2011 Jul-Aug;73(6):483-90
7. Jacka FN et al. A prospective study of diet quality and mental health in adolescents. PLoS One. 2011;6(9):e24805.