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 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.
1
