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Antibiotics and the Gut Microbiome: Implications for Health or Disease

Did you know that you are technically more bacteria than human? In fact, it is estimated that we have around 40 trillion bacterial cells residing in our bodies and only 30 trillion human cells. Regardless of bacteria having acquired a bad name (and for a good reason too) given their disease-causing reputation, whether you agree with it or not, your life depends almost entirely on these infamous microscopic organisms. 

Of the countless bacteria living in our bodies, the majority of these occupy our gut and their functional role in ensuring our survival has caused us to form a symbiotic relationship with them (where both humans and bacteria benefit) throughout the course of our evolution. From aiding us to assimilate and absorb nutrients released from digestion to secreting a toxic cocktail of acids that inhibit the growth of various diseases in our bodies, it is no wonder that the microbiome has famously been labelled as a “supporting organ” given its major role in the smooth functioning of our body processes.

The microbiome consists not only of trillions of bacteria of approximately 1,000 different species, but it also consists of viruses, fungi, parasites and countless other microscopic organisms. What’s more, each individual comes with its own unique microbiota system that is not only influenced by DNA, but also by diet and by various environmental factors, and therefore explains its contingent nature. 

As memorably described by the Harvard School of Public Health, “Picture a bustling city on a weekday morning, the sidewalks flooded with people rushing to get to work or to appointments. Now imagine this at a microscopic level and you have an idea of what the microbiome looks like inside our bodies, consisting of trillions of microorganisms…”

However, the microbiome is not only constituted by symbiotic microbes, a sizable portion of it is also made up of pathogenic bacteria. Although these typically coexist with each other in a peaceful accord, that is assuming that the body is healthy, issues may arise if there is a disbalance in one of these two. This is typically brought about through the abuse of medications, sickness, certain diets and many others, which can ultimately disrupt the smooth running of these interactions.

Now that you have acquired a general overview of the microbiome and its important role in maintaining the normal functioning of the body, let’s jump straight into the heart of the matter and discover how these often underrated superheroes actually benefit our bodies.

  • How does the microbiome affect our bodies?

This formidable army of microorganisms is not only involved in the disintegration of certain toxic compounds found in our food, but it also plays a major role in safeguarding us from pathogenic intruders that have entered the body via the ingestion of contaminated food and/or beverages. Even better, they help to synthesise, by their individual array of enzymes, a range of vitamins and amino acids, with B vitamins and vitamin K being amongst the most essential ones. In babies, these bacteria are especially important as they digest the sugars found in breast milk, which are essential for growth.

The microbiome in the gut further contributes to gut health by digesting carbohydrates that are harder to break down, including fibres and starches. Once the food has reached the lower part of the large intestine, these microorganisms secrete their unique digestive enzymes, thereby promoting the fermentation of these fibres, and subsequently breaking them down to their respective building blocks, short-chain fatty acids (SCFA). SCFA are not only said to be utilised by the body for muscle function and for preventing chronic diseases, but studies argue that they could serve as a potential treatment for ulcerative colitis, Crohn's disease, as well as antibiotic-associated diarrhoea. 

The microbiome’s extensive job does not only stop there. The bacterias’ job also includes inducing an immune response against myriads of dangerous viruses, including the norovirus, the flu virus and the infamous rotavirus, responsible for causing diarrhoea. These potent bacteria protect us from these countless viruses by instructing immune cells to secrete powerful antiviral proteins that target these viruses and eventually banish the infection. Even more, they inhibit the reproduction of dangerous bacteria by competitively acquiring the nutrients and binding sites located in one of the body’s most important places of immune activity, the mucous membranes of the gut.

Needless to say, the microbiome plays an essential and functional role in the stability of our body processes and contributes to our overall health. However, oftentimes, we may or may not be aware of some of the detrimental practices contributing to the harm done to these important microorganisms. Namely, the abuse of antibiotics is arguably amongst the most harmful ones that are worth mentioning.

Antibiotic treatments targeting bacterial infection are so good at their job that they also eradicate the beneficial bacteria inhabiting our gut that are susceptible to the specific medicine. Even if the antibiotic-resistant bacteria end up reproducing and taking the place of those eliminated, a disbalance is nonetheless displayed as a reduced divergence of the species accompanied by increased pathogenic development. Likewise, the overconsumption of antibiotics also contributes to the apoptosis (programmed cell death) of our intestinal cells and also impacts their reproduction. 

Further complications may also include certain changes to the immune system by potentially ebbing the mucous density covering the lining of our colon, thereby increasing the risk of infection. However, additional studies are still being carried out for further research. However, among the most commonly known impacts is antibiotic resistance, which is usually defined as “...the bacterium’s ability to elude the effects of certain antibiotics…”. 

Nonetheless, the effects of antibiotics on gut health depend on a variety of factors as each one may vary in their efficiency and intensity. For instance, whilst some may reduce microbiome diversity for only 4 months, others can disrupt this balance for up to 18 months! Other factors such as the length of the antibiotic course, the number of previous courses taken and even the overall health of the individual’s gut prior to antibiotic intake certainly influence the extent of the harm done both in the short term and in the long term.

It therefore goes without saying that we must do everything in our power to protect and maintain the overall health of the microbiome by limiting antibiotic use. Sometimes, taking antibiotics to treat minor infections such as sinus and ear infections may be tempting due to their rapid soothing effects. However, these usually leave on their own with time, and getting rid of them faster is probably not worth the pressure and strains put on our hard-working and dedicated micro friends.

The use of probiotics, which can restore gut flora to some extent, may also reduce the negative impact of antibiotic use. However, these must be taken with precaution regardless and consulting a doctor before use is always recommended. Also, maintaining good hygiene by constantly washing your hands for at least 20 seconds, using hand sanitizer containing 60% alcohol at best, and many other practices can prevent the formation of bacterial infections and can ultimately reduce the need to take antibiotics.

Overall, the next time you are tempted to make use of these powerful killers, reflect upon whether the illness is so terrible that it is worth the innocent bacteria’s brutal death and also consider whether the disease can typically cure by itself, just over a slightly extended length of time. 


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