It’s a Bug’s Life!

Most people are aware that the human body is filled and covered with trillions of bacteria, they outnumber our own cells 10 to 1 and we symbiotically co-exist – with an absolute interdependence. And yet the perception that bacteria are bad persists. Well of course some are, but many aren’t, read on to find out just what a valuable role they play in our lives.

Microbes inhabit different tissue niches within our anatomy as well as organ specific sites, and these various Microbiomes are generating a huge amount of research at the moment, enabled by new DNA technology. Microbial species that have evolved over millennia, and are much older than human life, have adapted to include us in their ecosystem and cross-talk and migrate within the body.  Phyla that hang out on the skin can also be found in the gut and though we used to think of the uterus as a sterile environment, we now see that maternal microbes move into the placenta and guts of embryos prior to birth, it’s not just the delivery route of newborns that transfers maternal bacteria.1,2 The arrival of bacteria in the new-born gut is essential to the full development of a balanced immune system.3

An American study (2014) involving 64,000 kids who’d taken antibiotics in the first 2 years of life, showed a significant associated increased risk of obesity to age 5, due to altered gut flora resulting from the antibiotics. Other studies show risk of allergy and asthma rises in children after antibiotics.

Recent research has also shown how non-caloric artificial sweeteners will alter the microbial ecology in the gut, and drive the development of glucose intolerance, raising risk of metabolic disease and diabetes.3 Artificial sweeteners are designed to pass through the gut without being digested, but nobody anticipated their effect on our gut microbes, enhancing the exact epidemic they were designed to halt.

There can be no doubt that modern behaviour and modern diets are altering the microbial ecology of humans. Proponents of the hygiene hypothesis know that a sterile environment growing up, increases risk of allergy as it’s the bugs that educate and keep our immune response balanced and appropriate.2  ‘Nurture your Microbiome’, could become the best piece of advice that a health practitioner gives, because it transpires they don’t just hitch a ride, our microbes aid detoxification, contribute nutritionally, inform the immune system, influence mental health and when imbalances occur, can not only influence our propensity to gain weight,  their absence – post antibiotic use – has repercussions for the gut’s barrier function leading to inflammation – which underpins all chronic disease.1


The last 50 years has witnessed an explosion of antibiotic use, both as medicinal prescriptions but also in the food chain. Don’t get me wrong, clearly antibiotics have their place, they revolutionised twentieth century control of infection, but balance is required now with antibiotic resistant pathogens evolving faster than ever. In addition, antibiotics exact a high price in the gut, with collateral damage to our microbial friends, so what are the repercussions of this?

Microbes hang out in the mucous layer as guardians of our gut’s ’barrier’ function. This allows dietary nutrients through, while keeping out unwanted intruders and undigested foods. So if antibiotics have disrupted the microbes and therefore this barrier function, it can result in more permeable intestines.

An overly ‘leaky-gut’ where passport control is less than effective will not only activate the immune system, the increased flow of toxins and antigens to the liver can potentially overload its detoxification capabilities. This can produce headaches and might exacerbate skin conditions, and I’ve no doubt the chemicals absorbed through our skin, from our lotions and potions add to the liver’s burden, whilst also affecting the surface skin’s microbiome. Have a look at the long list of unpronounceable chemical ingredients in your favourite body lotion. We absorb much of that and expect our poor old liver to deal with it, and that’s before we add 3 glasses of our favourite tipple to its load, just to wind down on Friday night!


So how should we nurture our gut Microbiome? Through good food choices! Vegetables in particular directly impact the diversity and ability of different species to flourish. Most people are aware of the health attributes of the Mediterranean diet, as it’s been shown to lower cardiovascular risk. A recent study threw up a very interesting fact: it looked at the food habits of 818 people aged 70 and over, from Sweden, Greece and Australia, and followed them over a 7 year period. It found elderly Greek-born Australians with a high prevalence of obesity and Coronary Vascular risk factors none-the-less had the lowest risk of death. How had they achieved this? The study concluded that it was not just their healthy Mediterranean diet in isolation, it was the fact that this diet – high in vegetables – beneficially altered their gut microbiomes and the resulting metabolites.5 A few years ago the researchers’ focus would have been to extrapolate single nutrient benefits from such a diet. Now we know that in addition, the whole vegetables themselves nurture abundant microflora in the gut, whose protective presence and metabolic effect induce enormous health benefit.

Gut – Brain axis

So what of brain health? How are our gut microbes influencing the central nervous system, with implications for neurodegenerative conditions, and autoimmune conditions like multiple sclerosis? Recent findings suggest that while certain gut microbes are protective against inflammation, others actually induce pro-inflammatory conditions like multiple sclerosis.6 Inflammation – a common, underlying factor in all autoimmune conditions – is likely resulting from toxic by products of pathogenic bacteria, passing through overly leaky gut tissue. Inflammation is common to all chronic, age-related disease, as well as mood disorders like depression, and a less than healthy gut – with or without symptoms – can be a constant source of systemic inflammation. So this represents really fertile ground for researchers who hypothesize that dysfunction within the gut microbiota, associated with altered diets, may affect the gut-brain axis and could be implicated in the development of mental illness and neurodevelopment disorders like autism.7

For integrative Functional Medicine, these are exciting times, with exciting implications for areas of disease that have so far struggled to make headway with conventional drug treatments.  Bottom line – eat more veg, to look after your friendly bugs who in turn will look after you!



1 Collins F (2014) Not Sterile After All:  The Placenta’s Microbiome. National Institutes of Health. Online:

2 Aagaard K et al., (2014) The placenta harbours a unique microbiome. Science Translational Medicine 6(237):237ra65

3 Suez J et al., (2014) Artificial sweeteners induce glucose intolerance by altering the gut microbiota

4 Hsin-Jung Wu Eric Wu (2012) The role of gut microbiota in immune homeostasis and autoimmunity. Gut Microbes 3(1): 4–14.

5 Kouris-Blazos AItsiopoulos C. (2014) Low all-cause mortality despite high cardiovascular risk in elderly Greek-born Australians: attenuating potential of diet? Asia Pac J Clin Nutr. 23(4):532-44.

6 Ochoa-Repáraz J et al., (2011) Gut, bugs, and brain: role of commensal bacteria in the control of central nervous system disease. Annals of Neurology 69(2):240-7.

7 Borre YE et al., (2014) The impact of microbiota on brain and behavior: mechanisms & therapeutic potential. Adv Exp Med Biol. 817:373-403

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