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The Role of The Gut In Health & Wellbeing

The role of the gut in overall well-being has been recognised for centuries. Hippocrates was spot on when he mentioned the gut as being the root of all disease. He followed this statement up by saying that bad digestion is the root of all evil. Nobel Prize winning author Elie Mitchnikoff made the famous quote “death begins in the colon” in the 1900s.

Modern research is increasingly pointing to the role of the gut in mood, immunity and allergies/intolerances. In particular, studies are linking the gut microbiome to a range of body functions and behaviours including appetite, cravings, mood, and emotions. Increasingly the gut is being linked to psychiatric and neurological disorders including anxiety, depression and autism.




The human body contains trillions of microbes which are collectively referred to as microbiome. This colony of gut flora is estimated to weigh two to six pounds – up to twice the weight of the human brain. This gut flora resides in the gut and intestines where it helps us to digest food, synthesise vitamins, and fight off infections.

Microbes make some of the same chemicals that our neurons use to communicate with one another, such as dopamine and serotonin. Microbes in our gut can deliver these neurological molecules to the dense web of nerve endings that line the gastrointestinal tract. A number of recent studies have shown that gut bacteria can use these signals to alter these signals to alter the biochemistry of the brain and therefore influence our behaviour[1].

Dr Sarkis Mazmanian, a researcher at the California Institute of Technology, is investigating the connection between gut bacteria, gastrointestinal disease and autism. He has found that the gut microbiome communicates with the brain through molecules that are produced by gut bacteria and then enter the blood stream. These molecules are strong enough to change the behaviour of the mice. Research has shown that this a metabolite produced by the gut bacteria is sufficient to cause behavioural abnormalities associated with autism and with anxiety when it is injected into otherwise healthy mice[2].

The microbiome is also though to influence the brain during development. Tracey Bale, professor of Neuroscience at the University of Pennsylvania has found that microbiome in mice are sensitive to stress and that stress-induced changes to a mother’s microbiome may be passed on to her baby and alter the way in which her baby’s brain develops. There a key developmental windows where the brain is more vulnerable to the mother’s microbiome as it is setting itself up to respond to the world around it. If the mother’s microbial ecosystem changes due to infection, stress or diet the newborn’s microbiome may also change which may have a lifetime effect[3].

Speculative research also points to the role of the microbiome in neurodegenerative diseases such as Alzheimers and Parkinsons disease.



Interestingly, new evidence is also pointing to the role of gut microbiome in determining our weight and our predisposition towards insulin resistance and Type 2 diabetes.

Gut bacteria is being shown to be increasingly important in determining how we store fat, balance levels of glucose in the blood, and how we respond to hormones that make us feel hungry or full.

A study demonstrating the cause and effect of intestinal bacteria and gut microbiome involved researchers raising genetically identical baby rodents in a germ-free environment so that their bodies would be free of any bacteria. The guts of the rats were then populated with intestinal microbes collected from obese women and their lean twin sisters. The mice ate the same diet in equal amounts, yet the animals that received bacteria from an obese twin grew heavier and had more body fat than mice with microbes from a thin twin. As expected, the fat mice also had a less diverse community of microbes in the gut[4]

The wrong mix of bacteria may also set the stage for obesity and diabetes from the moment of birth. Formula fed babies and infants delivered by cesarean section have a higher risk for obesity and diabetes than infants who are breastfed or delivered vaginally. Infants that are born through the vaginal canal swallow bacteria that will later help them digest milk. This is believed to be as a result of substances found in breast milk nurturing beneficial bacteria and limiting the colonization of harmful ones.



According to a Canadian study, the gut bacteria in formula fed babies versus breast fed babies are very different. The presence of gut bacteria from formula fed babies before the gut and immune system have matured may explain why these babies may be more susceptible to allergies, asthma, eczema, and celiac disease as well as obesity[5].

Studies have also found that children born via vaginal delivery have fewer allergies in subsequent years. Researchers believe is may be due to the babies having picked up certain helpful microbes from the vagina while physically being delivered through the vaginal canal[6].

New research is also pointing to the role of specific microbes in “desensitising” the body to allergies. A team led by Cathryn Nagler from the University of Chicago exposed three groups of mice to peanut allergens: germ-free mice without any resident bacteria, mice given antibiotics as newborns to reduce their GI bacteria, and control mice with a normal cohort of GI bacteria.

Germ-free and antibiotic-treated mice showed strong immunological responses, producing higher levels of antibodies against peanuts allergens — compared to mice with normal gut bacteria, which seem to provide some degree of protection against food allergies[7].


PROFILE: Anna Mitsios (Gut & Psychology Syndrome, Naturopath, Nutritionist)

As a nutritionist and naturopath, the foundation of Anna’s approach comes firstly from a place of sincere care and compassion and an unfounded determination to assist every client who crosses her path. Anna specialises in assisting people with autoimmune disease, children with autism/ADHD and behavioural disorders as well as people suffering from anxiety and depression. Anna is a certified Gut and Psychology (GAPS) Practitioner and focuses on healing the gut lining, intestinal dysbiosis and digestive disorders as the core of her treatment protocol.

Anna’s own experience with an autoimmune disease provides her with a strong understanding of nutrition, exercise and herbal therapy. It has also given her a deep empathy and a genuine desire to work together with you to deeply understand you and your health concerns and to provide you with the tools to make profound and lasting changes to not only your health but to your life. Anna’s previous life in the finance industry has given her a unique perspective of the demands of balancing a successful career and healthy lifestyle. So she particularly enjoy sharing insights on how to achieve work life balance given the demands of modern life. One of the things she particularly enjoys is helping you to find your true passion and calling in life and it is here that often the life changing component of her work begins.


[1] Stilling, R. et al. 2014. Microbial genes, brain and behaviour – epigenetic regulation of the gut–brain axis. Genes, Brain and Behavior. Vol. 13, 69–86.

[2] Hsiao, E. et al. 2013. Microbiota modulate behavioural and psychological abnormalities associated with neurodevelopmental disorders. Cell. Vol. 155 (7), 145-1463.

[3] Jasarevic, E. 2015. A novel role for maternal stress and microbial transmission in early life programing and neurodevelopment. Neurobiology of Stress, Vol. 1, 81-88.

[4] Ridaura, V. et al. 2013. Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science, Vol. 341 (6150).

[5] Horta, B. et al. 2007. Evidence on the long-term effects of breastfeeding: systematic review and meta-analyses. Geneva: World Health Organization. pp. 1–57.

[6] Azad, M. 2013. Gut microbiota of healthy Canadian infants: profiles by mode of delivery and infant at 4 months. CMAJ. Vol. 185 (5), 385-394.

[7] Stefka, A. et al. 2014. Commensal bacteria protect against food allergen sensitization. Proceedings of the National Academy of Sciences.

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