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10% Human: How Your Body's Microbes Hold the Key to Health and Happiness.

How would you react if you found out that there are approximately 3 microbes inhabiting our bodies per cell we have (which adds up to more than 100 trillion microscopic organisms using us as their host)? To some, the thought of being colonised by such a massive number of practically invisible bacteria may seem terrifying; after all, we’ve all been taught numerous times by our friends and family about the dangers of infectious micro-organisms like E-coli and Vibrio Cholerae. From here derives our constant need for hand-sanitisers and wipes rich in alcohol, among other disinfectants.

However, what most aren’t aware of is that without our colony of microbes, we wouldn’t be able to eat, think or even live like a normal human being.

Unfortunately, this was the case for David Vetter, most commonly known as ‘Bubble Boy’. The young boy suffered from a genetic disease known as Severe Combined Immunodeficiency, or SCID for short, which made him utterly vulnerable against pathogens. Having already lost their first son to the same disease, David’s parents decided to go through with his pregnancy, since doctors claimed that a cure for SCID was just around the corner. Therefore, David was born by C- section to minimise his contact with bacteria, and was immediately placed in a sterile plastic bubble after birth.

Throughout his life he was unable to leave his bubble, and never came into contact with another human being unless sterile gloves and equipment were involved. In this way, David managed to live a mostly microbe-free life (although doctors did find a small community of harmless bacteria in his faecal waste) until his death from lymphoma at age 12. Had David truly lived a completely germ-free life, forensics might have uncovered the effects of a lack of a microbiome on the human body during his autopsy: an enlarged caecum the size of a football and a small intestine with an abnormal small surface area were only two of the observations noted by scientists dissecting germ-free mice.

In order to understand the importance of our microbiome, we first need to establish the difference between what is most commonly known as ‘bad’ and ‘good’ bacteria. ‘Bad’ bacteria or pathogens are microbes which are harmful to us. When they invade their host (through contaminated food or water for example), they begin to reproduce at rapid rates and then proceed to carry out their ‘attack’ in different ways depending on the type of infection.

Some of these harmful bacteria naturally live within our own microbiome, yet are usually kept under control by the other species of beneficial microbes. Clostridium Difficile, for example, naturally lives in our gut. A disturbance to our microbiota could provide C. Diff with the perfect opportunity to take over. Dehydration, abdominal pain, kidney failure and a toxic megacolon are among the deadly symptoms experienced by sufferers of this troublesome bacterial infection, which also conveniently happens to be extremely resistant to antibiotics.

‘Good’ bacteria, on the other hand, first colonise our bodies during birth, as we pass from sterile conditions in the amniotic sac to an environment abundant in bacterial species belonging to genera like Lactobacillus and Prevotella when we transit our mother’s vagina. Both of these could be described as ‘milk-eating’, since they help us to digest milk and dairy, hence explaining why babies can drink only milk until they turn around 6 months old. Different species of microbes continue to colonise our body at different stages of our development, until the community is fully formed at around 3 years old.

Hippocrates once stated that ‘all disease begins in the gut’. As crazy as that may sound, it is not far from the truth— in fact about 80% of our immune system resides there, meaning that any disturbances to the balance of our gut microbiome could lead to the development of several diseases, some of them being potentially incurable and lethal.

It is believed that many 21st century illnesses like allergies, autism, diabetes and obesity could be caused by different alterations of our bacterial communities. However, the cause of such alterations may seem surprising to many; antibiotics. Thats right, antibiotics, which have prevented countless deaths from infection since their discovery in 1928 by Alexander Fleming, could be responsible for these vicious epidemics which we are fighting against today, as paradoxical as that may sound. Yet this theory becomes less ludicrous when taking into consideration the basic function of antibiotics, killing bacteria. An undesirable yet inevitable effect of taking these drugs means that ‘good’ bacteria will be eliminated too, hence the overuse of antibiotics (which is rapidly become a widespread cause of concern) could have grave repercussions on our microbiome.

Scientists are still far from fully understanding the human microbiota and its secrets, yet simply finding out about its existence has already meant a breakthrough for the scientific community, who is closer everyday to fully comprehending how our mental and physical health is linked to our microscopic allies, and hence what we can do to protect them.

Victoria M, Year 13

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