Last week we spoke more about the importance of the microbiome and how it is constituted. We mentioned that most of the microbiome is found in the large bowel, but also inhabits almost every surface and organ in the body. Various estimates indicate between 40-200 trillion micro-organisms – obviously no one can actually count them.
Let us talk a bit about the various types of micro-organisms in the gut. As was mentioned last week the Escherichia coli bacteria was one of the first to be identified. There are numerous other bacteria. The most beneficial are Lactobacilli, Bacterioides, Bifidobacteria and even Clostridium, (Clostridium welchii is commonly associated with gangrene, but most Clostridium species are actually beneficial, if not essential).
There are hundreds of different types of bacteria, some easily cultured in the laboratory and other not yet possible with current techniques. The diversity of gut microflora varies between 300-1000 species. Diversity is the key to gut health. We will learn later how that, as our diet has become more processed, the diversity of the gut has dramatically changed over generations, which means significant impact on our health and well-being and especially of our offspring.
There are many fungi genera that inhabit the gut, including Candida (yes Candida albicans is one of the harmful ones causing thrush, but there are many normal Candida species), Saccharomyces, Aspergillus, Penicillium etc.
Archaea is a group of organisms that is found in some of the most inhospitable places on earth – e.g. in methane vents at high temperatures in under sea canyons kilometres below the surface. These organisms in the bowel work in harmony with bacteria. According to Dr William Bulsiewicz they have been shown to protect us from coronary artery disease. Some bacteria cause the production of TMA from the digestion of carnitine in red meat and energy drinks, and choline in meat, eggs, high fat dairy and in some plants. TMA is converted into TMAO in the liver, and high blood levels of TMAO are associated with heart disease, but Archaea can inhibit the production of TMA and thus TMAO.
Very little is known about the protozoa (protists) that normally inhabit the gut that are not disease producing (such as amoeba, plasmodium, Giardia, etc). Numerous viruses are found there but these mostly inhabit the bacteria. Bacteriophages are the most numerous organisms on the planet, even far more than all types of bacteria combined. They are found within bacteria everywhere, including in the sea.
A fascinating article which is far too detailed to discuss in this short blog suggests that the fetal environment in the uterus is not sterile, and in fact the maternal mouth micro-flora has more impact on the intra-uterine microflora than the vagina, skin or nasal microbiome.
However some studies have also shown that maternal intestinal microflora may be transmitted through the blood stream into the placenta. It used to be taught that meconium (that greenish, slimy first “poo” that babies produce at or after birth) was sterile, but it has now been proved that there is already a healthy variety of organisms at that stage. Once birth has occurred the gut microbiome spectrum undergoes fundamental shifts, to mimic more that of the mother. This can be heavily influenced by the method of child-birth – whether vaginal delivery or C-section, exposure to antibiotics, whether breast or bottle fed and sanitary practices. It has been reported that mother’s milk has up to 700 different species of bacteria.
The diversity and composition of the microbiota significantly changes in the first 3 years of life to resemble that of an adult.
“Therefore the first 3 years of life represent the most critical period for dietary interventions to improve child growth and development. The composition of this microbiota is a vital asset for health and neurodevelopment”. This fact means that how and what we feed our children in their early years can impact their lifetime health. Anyone wanting to read more about the changes in the gut microbiota and its effect on childhood development can read this very comprehensive article
An interesting fact brought out by Dr Bulsiewicz, alluded to above, is that our diet can significantly impact the diversity of our gut microbiome. This then affects the gut diversity of a mother’s children and even her grandchildren, each losing significant diversity and resulting in dysbiosis – or disturbed micro-flora. A woman may start out with around 1000 different species of bacteria, but with eating a Western type refined diet, she may reduce her diversity to say around 600 species. She passes this on to there children. If they adopt a similar diet, her daughters may pass on a significantly reduced diversity to their children.
Next week we will talk about prebiotics, probiotics and postbiotics (a new concept).
Also covered in this blog will be ways in which we can enhance the growth of a healthy microbiome, as well as how to damage it. This is particularly relevant in terms of how we are able to handle viral infections such as Covid-19. Remember a large part of the immunity of the body resides in the gastro-intestinal tract.
Stay safe, and maintain safe preventive practices.
Dave Glass
Dr David Glass graduated from UCT in 1975. He spent the next 12 years working at a mission hospital in Lesotho, where much of his work involved health education and interventions to improve health, aside from the normal busy clinical work of an under-resourced mission hospital.
He returned to UCT in 1990 to specialise in obstetrics/gynaecology and then moved to the South Coast where he had the privilege of, amongst other things, ushering 7000 babies into the world. He no longer delivers babies but is still very clinically active in gynaecology.
An old passion, preventive health care, has now replaced the obstetrics side of his work. He is eager to share insights he has gathered over the years on how to prevent and reverse so many of the modern scourges of lifestyle – obesity, diabetes, ischaemic heart disease, high blood pressure, arthritis, common cancers, etc.
He is a family man, with a supportive wife, and two grown children, and four beautiful grandchildren. His hobbies include walking, cycling, vegetable gardening, bird-watching, travelling and writing. He is active in community health outreach and deeply involved in church activities. He enjoys teaching and sharing information.
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