One of the giants in scientific discovery was Antonie van Leeuwenhoek, who in 1677 published the first document on micro-organisms. He is universally acknowledged as the father of microbiology. He even developed his own microscope, which was state-of-the-art at the time but very simple by today’s standards. This allowed him to see what he called “animalcules”, now known as protozoa and bacteria. As no-one else had made a microscope, which meant his findings could not be confirmed, he struggled to get his work published, as many scientists thought he just had a vivid imagination!
The study of micro-organisms has come a very long way since then, but especially in the last 20 years with genetic sequencing. Although no-one can actually count them, it is estimated our body contains around 100 trillion micro-organisms, most inhabiting the large bowel, compared to only around 10 trillion human cells in our whole body. That is a ratio of 10 to one. The Human Genome Project estimated that each of us has between 20 000 to 25 000 genes, responsible for everything from the colour of our eyes, to the shape of our nose, the length of our fingers, even to the design and normal functioning of every organ of the body.
It is estimated that a healthy person harbours around 1 000 different species of micro-organisms, which contain approximately 2 million genes, according to the findings of the Human Microbiome Project. Far from being just innocent or harmful passengers, these micro-organisms have profound effects on many aspects of our health. They are responsible for digesting substances in our diet which our own digestive enzymes are incapable of breaking down. They manufacture various chemicals vital for our immune system, the integrity of the intestinal wall, for controlling metabolic functions widely in the body, and even for the production of neuroactive substances used in the brain. A disordered gut microbiome has been fingered in such diverse conditions as depression, Alzheimer’s disease, Parkinson’s and even autism spectrum disorder.
Perhaps the most important products of bacteria are short-chain fatty acids (SCFAs) – butyrate, propionate and acetate (vitamin C). In the gut these SCFAs maintain the integrity of the intestine, stimulate the production of mucus, and protect against local inflammation.
These chemicals are also important in metabolic and endocrine functions. In an article in the on-line journal PMC published last year, SCFAs are reported to have wide effects in the body, including anti-inflammatory, immunoregulatory, anti-obesity, anti-diabetes, anti-cancer, cardiovascular protective, liver protective and neuroprotective activities. Bowel disorders such as ulcerative colitis, Crohn’s disease and antibiotic-associated diarrhoea may be prevented or managed by improving the diversity and quantity of gut micro-organisms.
A common modern phenomenon is gut dysbiosis – a fancy word for the dysfunctional or disordered microbiome. To obtain the full benefit of a healthy gut microbiome we need a wide diversity and a healthy number of these micro-organisms.
Many factors impact that diversity, which we will discuss in future articles. But briefly, our lifestyle – diet, physical activity, stress levels, sleep habits, use of harmful substances – has a profound effect on not only our own health, but also the health of our micro-organisms (the microbiota). The healthier they are, the healthier we are.
To return to the title of this article “Were you ever who you were?”, we are deeply indebted to the health of our 100 trillion microbiota for our well-being. They deserve our respect and nurture. What we eat has much to do with their health. How we accomplish that will be the subject of our next article.V This health column is written by Dr Dave Glass, a retired obstetrician/gynaecologist living in Somerset West for just over a year. He is also chairperson of the South African Lifestyle Medicine Association (Salma). Glass, with a MBChB, FCOG(SA) and DipIBLM, has a passion for preventing and addressing the root causes of chronic diseases such as diabetes, heart disease, auto-immune diseases, obesity, dementia and cancer.
