The Human Microbiome: do not underestimate microbes!

Over the last two decades research has revealed the importance of our gut bacterial flora to our health and wellbeing. This collection of microbes is called the microbiome and consists of millions of symbiotic bacteria, mostly in our guts, which are necessary for our digestion and general health. Within these millions of bacteria, there are of course pathogenic bacteria and viruses, but these are kept in check by the microbiome, unless they become a serious infection. A typical human has over 10tn cells, but there are 10x more cells that make up the microbiome, giving it a mass of about 3Ibs in total, roughly the same as a human brain.


Research is beginning to unravel the importance of these microbes to our digestion, immune system and even behaviour.  It has been being suggested that modern life styles have caused imbalances in the microbiome and this may be the reason for many modern prevalent diseases, such as diabetes, irritable bowel syndrome, obesity, asthma and eczema.  Poor diet, smoking, alcohol, processed foods, sanitation and medication, all may play a role in the imbalance of the biome and hence, symptoms and diseases that are far too common in the industrial world, yet often significantly less common in the underdeveloped economies. But it is not just our guts we need to worry about – let us not forget the bugs that inhabit our mouths, our genitals and our skin.

When born by natural means, a baby gets a mouthful of bacterial flora as its passes through the vaginal canal and then receives further microbes from the mother’s skin. It is interesting to note that babies born via caesarean section are statistically associated with high rate of a broad range of diseases and conditions. For example, children born through c-section are 20% more likely to be obese.

The microbiome is also an essential modifier of the immune system, as 80% of our immune system is located in the gut. There is evidence for the so-called “hygiene hypothesis”, which helps explain the explosion of autoimmune and allergenic diseases that have appeared over the last half century. Children brought up on farms or in households where they are exposed to pets or more dirt and soil are less likely to develop asthma or diabetes, for example. Although there is no absolute proof of the hygiene hypothesis, there is growing evidence. It also explains why many scientists believe that we use far too many disinfectants in our homes in an attempt to keep our houses clean. Such actions may also negatively impact on our health in the long term, especially for children who will not be exposed to a natural background of microbes so that they can develop acquired immunity.  The other big issue is the amount of antibiotics people take; 4 out of 5 US Americans were prescribed antibiotics. Clinicians and healthcare providers prescribed 258 million courses of antibiotics in 2010, for a population of 310 million. The impact on the microbiome is considerable, especially in the use of wide spectrum antibiotics, which are less discriminating in their anti-bacteriostatic or anti-bactericidal effects.


So if you have an unbalanced microbiome and always have an upset stomach or other irritating condition, what can you do?  Well you can start eating a wider variety of foods and make your intake more like that of our ancestors thousands of years ago, with a rich mix of nuts, berries, root vegetables and a limited supply of meat. You can also consider probiotics, but the volumes you need to ingest are so large that they are not really that effective in their commercial forms. You can, however, eat foods that are high in probiotics such as artichokes, leeks, celeriac and chicory.

Finally, there is the ultimate way to get your biome rebalanced – the fecal transplant or Fecal Microbiota Transplant , which involves taking a healthy stool sample from an individual and placing it inside a patient who has suffered from gastrointestinal problems, probably  owing to an imbalance in their microbiome. The procedure is especially useful when a patient has become overrun by a nasty bacterium called Clostridium difficile, which can take over a colon following an infection.

What is fascinating is that for some many years, biologists and clinicians have looked to physiology and biochemistry for answers in relation to the development of certain diseases. It was well understood that certain pathogens are the causative agents of diseases, such as Mycobacterium tuberculosis for tuberculosis or TB, but what was not clear was the influence that the microbiome had on our general health, disease, behaviour and psychology.


John Dalton, 2015

Head of Science 

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