Your Life, Your Gut

Updated: Sep 20, 2020

There has been so much recent research into the effect that the make up and changing composition of our gut microbiota has on both physical and mental health.

A recent lecture that I listened to by Dr. Helena Popovic, ambassador for the Gut Foundation of Australia opened my eyes to yet more influences, beyond food, on the gut microbiota.

All of this goes to highlight the importance of a whole lifestyle approach to a healthy body and mind, and to keeping the gut 'happy' because of its far reaching effects on just about everything else.


No-one knows what the perfect composition of the gut microbial population might be. The likelihood is that it is slightly different for everyone. What we do know is that a wide diversity of types of microbes, and high numbers of microbes is good, and that certain species tend to not be helpful, whereas others do tend to be beneficial. We do want bacteria which produce short chain fatty acid metabolites, but very specific strains of bacteria are helpful for different conditions, and so it is hard to generalise. Lactobacillus and Bifidobacteria species are good species to have plenty of. However, although we associate E.Coli with food poisoning there are actually some strains of E.Coli which are beneficial.


So what, other than way we eat, can influence the make up of our gut microbiota?

The answer is almost anything.



Even before we are born, a mother's stress levels affect her microbiota, which are transferred to the baby on birth. Caesarean section means that the baby misses out on these bacteria which are acquired in the passage through the vagina. There has even been talk of probiotics to make up for that lack in Caesarean born babies! After birth, the connection continues through breast milk, thus happy, relaxed mum, happy baby! On the flip side, a stressed mother's vaginal lactobacilli are altered and this affects the amino acids that are available for interconnecting the baby's brain regions, thus brain development can be affected.


Our microbes are also affected by whether we live in an urban or rural environment (hint: get some soil on your hands!), our pets, whether or not we exercise and how much, antibiotic use, siblings, conflict, sleep, medication use, mouth wash use, bullying and whether we had our tonsils or appendix out before the age of nine years. Who knew?!


Feeling overwhelmed and powerless in the face of all that information?

The key is to recognise what you can influence and what is in the past.


Childhood trauma, whether at home or school manifests as a very different microbiota compared to children who did not experience trauma. This often results in gut symptoms such as tummy aches and, later on, irritable bowel syndrome (IBS). Up to 50% of people with IBS have experienced childhood trauma. Their history cannot be changed, but seeking help to deal with the trauma may be as useful as dealing with the IBS symptoms as the microbiota is highly changeable. With positive changes in composition come mental health benefits. Equally, with stress reduction, come beneficial changes to the microbiota, therefore it is a mutually interdependent system. However, small incremental changes and patience may be required since a poor 'baseline' microbiota may make improvements slower to achieve.

Conflict is an an interesting case. One would expect that 'losers' would have more 'damage' to their microbial population than 'winners'. However, in hamsters (studied because they fight for dominance at a young age), microbial diversity is reduced in both winners and losers after conflict. Even stranger, researchers could tell from looking at the microbial species in hamsters before a fight which was more likely to win!


Bullying, or anything that affects your sense of self worth, causes breaches in the blood brain barrier. This causes inflammation which in turn makes you more vulnerable to depression.


Medications which interact with the microbiota are numerous. The interplay is two way - medicines affecting the microbiota and the microbes affecting the efficacy of response to drugs. This is not confined to antibiotics, even non-antibiotic medications can affect the microbiota, in fact a study found that 250/923 medications inhibited at least one strain of bacteria commonly found in the human gut. There are 40 common medicines which affect at least 10 bacterial strains! The strongest microbial disruptors are laxatives, Metformin (diabetic drug) and oral steroids, such as the Pill. Oral steroids seem to be associated with a rise in methalogenic bacteria which are associated with weight gain, which may explain why women report weight gain when on the Pill.

Antacids (proton pump inhibitors) are also a common medication that affect the microbiota. They are often used in conditions such as acid reflux. The higher the dose, the more likely it is that the patient will experience depression. Luckily, the one most commonly prescribed in Australia - Amiprozal - is also the one least associated with depression.


The microbes harboured in our bodies are not just in the large intestine. Many are found in the mouth. There are bacteria in the mouth which recycle nitric oxide which we produce when we do physical exercise in order to dilate blood vessels. Therefore physical exertion lowers blood pressure. However, using mouthwash affects those oral bacteria and reduces the systolic blood pressure lowering effect of exercise by 60%! Even when used at a totally different time to when physical activity is carried out, the mouthwash still compromises the blood pressure lowering effect. It also raises the acidity of the oral environment, making us more prone to tooth decay. The moral is that unless you have compelling reasons to use a chlorhexidine mouth wash, don't!


There is so much to explore in this area. Suffice to say that everything in our bodies and the environment is interrelated. All manner of things affect our gut microbial population, and therefore our health.


Some simple things that you can do, beyond eating a diet high in fibre and plant foods, to benefit your gut are:

- Sleep. Seven or more hours per night of undisturbed sleep is ideal.

- Exercise. Regardless of diet, exercise increases diversity and favours short chain fatty acid producing bacteria in the gut. Half an hour per day on 6/7 days is enough to see the benefit, but you have to keep it up!

- Get out in Nature. Getting out in nature makes you less prone to stress, anxiety and depression. This may be partly due to inhalation of bacteria! Mycobacterium vaccae in the garden stimulates cells to produce serotonin, the happiness hormone! Weirdly however, in prisons and hospitals, patients/inmates fare better when they have a room with a nature view, not even contact with nature!


Everything that we do affects our gut flora. Live simply, interact with nature and minimise your use of chemicals. And of course EAT well!


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