What if I told you that more than 90% of the genes and cells in your own body don’t belong to you. I don’t mean that your genes are not “your” genes because they are inherited from your parents. No, I am talking about the genes and cells from other organisms altogether; specifically those that belong to the collection of bacteria and other microorganisms that are found all round the human body. You may have heard about “good bacteria” via some probiotic yoghurt adverts that aired a few years back. Well we are literally teeming with microbes and live, for the most part, in mutually beneficial symbiosis with these microscopic organisms. Up until relatively recently bacteria were primarily thought of as the bad guys but huge advances in microbiology including sequencing methods and analytical techniques are starting to help us understand just how good these guys are for us. This is one of the hottest areas in scientific research just now.
10 Awesomely Cool Microbiome Facts
- Although the terms “microbiota” and “microbiome” tend to be used interchangeably outside of academic circles, technically speaking the microbiome refers to the sum of all the genes of all the microbes in a community whereas the microbiota refers to the sum of all the microbes in a community.
- The typical human has about 10-100 trillion microbial cells – these are primarily bacteria which are found in the gut although the microbes also as well as bacteria there are also viruses, fungi, archaea and protists and as well as the gut there are also microbes in many other parts of the body e.g. lungs, mouth, vagina and skin.
- We are not actually born with our microbiota intact. The first “hit” of microbes occurs as the baby passes through the birth canal and then through breastmilk and through environmental exposure; a baby will have acquired much of its microbiome by the age of 3.
- For this reason babies who are born by C-section and those who are primarily formula fed tend to have lower numbers of microbes compared to vaginal birth and breast-fed babies and the former show higher instances of allergies e.g. asthma and eczema.
- You can alter your microbiome (for better or for worse) through diet. There are “probiotics” which introduce new microbes into your gut and are particularly prevalent in fermented foods. There are also “prebiotics” which feed the existing microbes and are particularly prevalent in foods high in arabinogalactans e.g. onions, kiwi, carrots and radishes.
- Microbes themselves are responsible for creating foods such as wine, cheese, yoghurt, sauerkraut and vinegar.
- Human breast milk contains oligosaccharides, sugar molecules that provide absolutely no nutritional benefit to babies. Why do mothers spend energy making these molecules? It’s to feed microbes that are important for the baby’s developing immune system.
- It is not just humans who share their space with billions of microbes. ALL plants and animals are a so-called “holobiont” consisting of a host and its microbes.
- There are some incredible examples of symbiosis in the animal kingdom. For example some types of bacteria called “wolbachia” infect a range of animals that include insects and roundworms. In some species, the bacteria cause sexual incompatibility. Infected parents can reproduce with each other, and so can uninfected parents. But an infected parent and uninfected parent can’t reproduce together. Wolbachia infection may create the “reproductive isolation” necessary for one species to diverge into two.
- Despite most microbes being at worst harmless and at best essential to humans, a small number can cause disease and have led to millions of deaths across the centuries. We call these microbes “germs” and refer to their symbiosis as “pathogenic”.
Whilst there is a good decade plus of research into microbes and the human microbiome there is a suspicion that we are only just starting to uncover just how important they are to our health and indeed survival. An impaired microbiome (also called “dysbiosis”) is starting to be linked with many illnesses such as depression and axiety, IBS, coeliac disease, obesity, cardiovascular disease and more. Expect to hear more and more about the microbiome and microbiota over the coming years.
I contain multitudes by Ed Yong