4 minute read
How do we benefit from the microorganisms that live within us?
By Nancy Stitt, U6 JHB
Our bodies are an ecosystem of trillions of microorganisms that live within us: science calls it our “microbiome”. We consist of approximately 10 trillion human cells, but inside us we harbour as many as 100 trillion microbial cells. We are vastly outnumbered by our microbial companions, but how is this beneficial to
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us? We are only beginning fully to understand our complex and crucial relationship with our microbiome, but already there has been significant progress, especially in the fields of obesity, immunity, digestion and mental health.
We benefit from our mother’s internal microorganisms at the very beginning of life. As a foetus, we are encased in an amniotic sac and muscly uterus that prevents us from coming into contact with a single microbe. We will never again be so safe from infection. However, as soon as there is a break in the amniotic sac, colonisation begins. While 100% of the cells that make us up when we start life are human cells, we are soon colonised by so many microbes, that by the age of 3, only 10% of our cells are human - microorganisms account for the other 90%. If you are born vaginally, the first bacteria that you come into contact with are your mother’s vaginal flora. This useful layer of bacteria coats the sterile body of the baby as it is born and is absorbed into its stomach, where it produces lactic acid, preventing our large intestine from being colonized by harmful bacteria, and promoting good gut health. Breastfeeding also provides us with microorganisms that populate our gut. Colonising our gut so early, these can be crucially important in the development of later bodily functions, like the immune or metabolic systems. Children who have not been breast fed may have insufficient Bifidobacteria in their gut in their first year, which shockingly increases their risk of obesity in later life.
The microorganisms that live within us also benefit our immune system, 80% of
which is located in the gut. The majority of microbes in our gut protect us by simply occupying spaces that would otherwise be free for harmful bacteria to colonise. Some of these microorganisms release compounds that decrease inflammation, keeping beneficial microbes safe by blocking attack from our immune system. A study showed that people with less inflammation have a lower risk for cancer.
Our digestive system also benefits from the microorganisms that live within us. Our gastrointestinal tract contains over a thousand different species of bacteria,
in addition to minority populations of viruses, yeasts and fungi. These microbes increase the value of our food by releasing nutrients that would otherwise be undigested; up to 10% of the calories we absorb from food are made available by microbes.
We also benefit from our internal microorganisms mentally. Our microbes produce compounds which signal brain cells to divide and are thought to be so important for learning in developing brains, that they are often added to baby formula. Our gut is surrounded by 500 million neurones, which can sometimes be called ‘the second brain’. Information is mainly transmitted between the gut and the brain through the vagus nerve, which reaches certain areas of the brain associated with emotion, motivation, memory and morality. This suggests that
the health of our gut and its microbes may have a certain influence over our mental wellbeing. We often say phrases like “I have a gut feeling” or “I have butterflies in my stomach”, but may not realise that our gut microbiota may actually be affecting and even benefitting our mental health.
As our understanding of the relationship between our bodies and our
microbiome increases, our ability to diagnose and treat diseases will also develop. One exciting treatment that has developed from research into our microbiome is for the disease commonly known as C diff, a serious condition that causes patients to suffer from frequent bouts of diarrhoea. A 21-month old Hispanic girl with recurrent Clostridium difficile infection suffered for a whole year without an effective treatment, but amazingly, after a ‘maternal donor faecal microbiota transplantation was performed’, her symptoms cleared up, and she has been free of the disease for the past 5 years. In future, this way of harnessing our microbes may lead to increased use of probiotics to regain a healthy microbiome, better
diagnosing of disease, the creation of personalised diets, and may even play an important role in a whole new era of personalised medicine. We can be sure that exciting progress lies ahead in understanding the beneficial link between our microbiota and our wellbeing. Microbes are not our enemies, but our healthgiving friends!
