Summary of Follow Your Gut by Rob Knight

BookSummaryClub Blog Summary of Follow Your Gut by Rob Knight

Bacteria are everywhere. They have acclimated to some of the harshest environments on the planet and continue to thrive. If we really think about it, if it were not for microbes, life as we know it would not exist. They play an integral part in decomposition and the nutrient cycle. Can you imagine what it would be like if they did not exist? Sure, diseases like cholera and tuberculosis would not exist, but then again, how would our body break down food and obtain the nutrients necessary for survival? 

In fact, there are more microbes in our bodies than there are cells. Surely, this is a clear indication of how important these tiny things really are. Maybe it’s time that we start giving them a bit more of our attention.

In this book summary readers will discover:

  • Why microbes are essential to your health from the time you are born
  • How microbes influence anxiety and weight
  • Probiotics, Prebiotics and Antibiotics

Key lesson one: Why microbes are essential to your health from the time you are born

When babies are in the womb, they are essentially protected from everything, including microbes. But even though, babies in utero have yet to come into contact with microbes directly, they indirectly benefit from the microbes in their mother’s gut. When women are pregnant, the microbes in their gut actually changes to enable the extraction of more nutrients. This ensures that both mother and child have enough nutrients during pregnancy.

Babies pick up their first microbes whilst being born. As they pass through the birth canal, they are exposed to their mother’s microbes. In fact, scientists have actually found evidence that some microbes increase in pregnant women’s genitals in preparation for birth. As the baby passes through the birth canal, these microbes are transferred from mother to child and act as a protective layer.

Therefore, one can clearly see that children born via caesarean section do not receive these microbes. These children pick up microbes from their mother’s skin as opposed to the birth canal. So, the protection they receive may not be as strong as children born naturally. More studies need to be conducted to establish the exact difference between caesarean section and naturally born babies however, it has been shown that caesarean section babies may be more susceptible to microbe related diseases. Since it is quite common and convenient for most children to be born via caesarean section, mothers must be aware of the microbial consequences as well. There is a way to work around this, as the Knight and his wife found out. When their child was born via caesarean section, they transferred microbes from the birth can to the baby using sterile cotton swabs. Once swabbing the birth canal, the microbes were applied to areas in which they would have naturally settled during birth. This ensures that the baby gets what it needs.

The microbial cells in our body continue to proliferate as we grow and eventually outnumber the cells in our body. We have almost 10 times more! And whereas all humans share 99.99 per cent of their DNA, the microbes in our gut are no more than a 10 per cent match. Scientists can even identify your computer mouse with 90 per cent accuracy given the microbes in and on your body! The microbes on our hands are 85 per cent different from others. Therefore, everyone has a microbial fingerprint. The microbes on your skin can even make you more or less attractive to mosquitoes! This is why some people get bitten more than others. The microbes feed on the secretions on our body and determine our body odour and this scent can be more attractive to mosquitoes.

The microbes within you are also responsible for a variety of tasks. The vast majority of microbes within us are found in our intestines. They aid in digestion, processing dietary fibre, how many calories are extracted from food and even how your medication affects you. 

Key lesson two: How microbes influence anxiety and weight

Did you know that microbes determine how much you weigh? Very few diets acknowledge this. Scientists have proved that microbes can determine weight using mice. They transferred the microbes of an obese mouse to a slim mouse and monitored the effects. The slim mouse became obese. They then transferred the microbes of a slim human to a mouse living with an obese mouse. This seemingly prevented the transfer of microbes of the obese mouse to the other, keeping it slim. 

But, other than your weight, the microbes in your gut can also have an effect on your anxiety level and how your brain works. A connection exists between your gut and your brain. It is called the microbiome-gut-brain axis. To understand this connection, let’s take a closer look at depression. When one experiences a depressive phase, they often also experience inflammation in the bowels as well. This inflammation can cause a type of bacteria called oscillibacter, to produce gamma-aminobutyric acid which is a natural tranquillizer. Gamma-aminobutyric acid can calm the brain and is used in sleep supplements but, it can also lead to depression. 

Microbes in the gut can also prevent autism. Scientists at CalTech isolated the molecule responsible for autistic behaviour, 4-EPS and injected it into mice. All the mice thereafter exhibited autistic behaviour. However, if these mice were injected with a microbe called Bacteroides fragilis, some of the symptoms of autisms were reversed. It also repaired gut and cognitive problems. Human trials have not been conducted but this just demonstrates the power of microbes. They could hold the key to treating and helping people with autism. 

Key lesson three: Probiotics, Prebiotics and Antibiotics

Lucky for us, there are ways in which we can maintain a healthy microbiome. One of these is probiotics. Probiotics are sold as supplements, suppositories and food such as yoghurt. They contain strains of bacteria or other live microorganisms that are considered to be beneficial. However, it is common that these bacteria are already present in your gut. Studies have shown that these probiotics can help adults with irritable bowel syndrome and kids with diarrhoea. 

Besides probiotics, prebiotics also provides a way to improve the way your body’s microbes work. Prebiotics are made up of inulin, lactulose or galacto-oligosaccharides which are all foods that microbes like to eat. So, by taking prebiotics, you are providing the microbes in your body with everything they need to function optimally and multiply. They serve as a substitute for a healthy diet high in fibre. Humans once had healthy diets high in fibre, but that has substantially decreased in modern times. Studies have shown that prebiotics has a positive effect on constipation, insulin resistance, inflammatory bowel disease and Crohn’s disease. 

Probiotics and prebiotics both help microbes, however, it is also worth taking a closer look at the stuff that microbes hate – antibiotics. Ever since Alexander Fleming discovered penicillin, antibiotics have been used to cure all sorts of bacterial diseases. There is no denying their positive impact in the world of medicine. However, antibiotics sometimes have unintentional side effects which can affect our microbes drastically. They don’t differentiate between disease-causing bacteria and beneficial bacteria. They can damage our microbiota by completely killing beneficial bacteria. There have even been studies done where they have shown that antibiotic use in the first six months of life has an effect on the natural development of Bifidobacterium which is an important piece of a healthy immune system. Lack of Bifidobacterium can result in people having asthma and allergies when they are older and can even cause weight gain.

The scenario we are all familiar with is the development of antibiotic resistance. Every time we do not complete a course of antibiotics, there is a risk of creating antibiotic-resistant bacteria within us. This is why we should always complete a course of antibiotics even if we are feeling better. It will benefit us in the long run. 

Antibiotics in agriculture have also been abused because of their effects. Farmers discovered that animals that received low doses of antibiotics gained weight faster. If they gained weight faster, they could be slaughtered earlier and farmers made more money. However, these low doses of antibiotics led to more and more bacteria becoming antibiotic-resistant. Farmers now find themselves in situations where normal antibiotics no longer work on diseases that were previously cured easily. Due to this, the EU has banned low dose antibiotic treatments altogether however it is still practised in other countries. 

Antibiotics can only be helpful if used correctly. The more people do not use them correctly, the more problems we will face in trying to control diseases in the future.

The key takeaway from Follow Your Gut is:

Microbes are much more important than we give them credit for. As much as we can easily appreciate the beneficial microbes in our environment, we often forget our very own little ecosystem of microbes within us. They are with us from the very moment we are born and contribute to our overall well-being. Not only do they determine our weight and physical health, but they also influence our anxiety levels, mood and how much nutrients we take up. We can take an active approach to maintain a healthy microbiome in our bodies by ensuring we follow a healthy diet high in fibre and by using prebiotics and probiotics. We should also always endeavour to use antibiotics wisely to prevent resistance.

How can I implement the lessons learned in Follow Your Gut:

Ensure that your gut and microbiome has everything it needs to function optimally. You need to follow a diet that is high in fibre and take probiotics and prebiotics when needed. This is also extremely important to follow after a course of antibiotics which may have unintentionally destroyed the natural balance of microbes in your gut.

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