Month: December 2020

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We are a home for trillions of microbes — bacteria, fungi and viruses — our microbiota, whom we are tightly connected with. Our biological identity and health are intertwined with that of our microbial partners.

You might´ve heard that your gut plays an important role in your overall health & well-being. But I’m convinced that you aren’t even close to fully appreciating what the impact is for you. Every year more evidence keeps pouring in about the importance of gut health and the balance of gut microbes.

Think of it as a very complex highway system, with traffic going back and forth at high speeds on many different levels, directions and junctions. Our body affects the community living in our gut, and these microbes produce metabolites, the small compounds that regulate different functions in our body.

Firstly, the gut microbiota is tightly connected to digestion and metabolism. Gut microbiota helps break down food and absorb nutrients. Our own body can digest most, but not all of the food we eat. The food our body cannot digest, especially dietary fibers, makes its way to the end of the large intestine, which is packed with gut microbes. This is the most largely and diversely populated part, because the environment is stable and rich in nutrients.

In the colon, the end part of the large intestine, gut bacteria break down the undigested food that they use as a source of nutrients. Gut microbiota helps us to get approximately 10–15% more energy from our food — mostly from dietary fibers. While breaking down dietary fibers important metabolites are produced. For example, gut bacteria produce short-chain fatty acids (SCFA), which are important sources of energy for both human and bacterial cells. For example the cells that form the gut lining get up to 70% of needed energy from one of the SCFA, called butyrate. Gut microbes also produce essential K vitamins and different B-group vitamins from dietary fibers.

Secondly, about 80% of our immune system is located in the gut, where gut microbes play a central role in. The metabolites that bacteria produce, communicate also with our immune system both directly and indirectly. In addition, these compounds support the production of mucus in the gut, which forms a supportive and strong gut barrier. This barrier protects against pathogens and toxins that evoke inflammation. And of course diverse communities of microbes protect against the overgrowth of harmful pathogenic bacteria while competing for food and space.

Moreover, gut microbiota forms a linked axis with the brain and nervous system, prompting many scientists to refer to as “the second brain”.

We’ve all probably heard of the “happy hormones” serotonin and dopamine. We used to think these hormones are produced in the brain. But take a moment to really consider this: up to 95% of serotonin and about 50% of dopamine are produced in the gut. These hormones are responsible for controlling your mood and are associated with the feelings of happiness.

All this time we´ve been looking for happiness in the wrong places!

Scientists used to think depression and anxiety caused or contributed to gut problems, but now there is evidence to show it could be the other way around, that inflammation in the gut could influence the development of mental disorders such as depression and anxiety.

To meet the beneficial effects of gut microbes, it is important that the microbiota is diverse and balanced. Otherwise the effect can be the other way round — your allies can become the enemies. An unbalanced microbiota can promote the development of various diseases — metabolic diseases like obesity and type II diabetes, neurological disorders like anxiety, depression, autism spectrum disorders, heart and kidney disease, cancer, autoimmune diseases and many other illnesses.

If you don’t have good relationships with the communities living in your gut, you´ll always be struggling to get into a balanced healthy state.

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The past decade has shed light on the role of the gut microbiome in human’s overall health. Gut microbiome pertains to the collective bacteria, viruses, and fungi that live in our gut. It has become clear that our health is intertwined with our microbes.

Think of it as a very complex highway system, with traffic going back and forth at high speeds on many different levels, directions and junctions. Our body affects the community living in our gut, and these microbes regulate different functions in our body.

Your digestive tract is one of the main contacts of your body to the outside world — all the food that you eat passes through it. Throughout the gastrointestinal tract reside different communities of microbes.

The digestive tract starts from the mouth, which is responsible for grinding the food into smaller chunks. Also the digestion of starch starts in the mouth. Mouth is home for about 20 billion microbes.

Next, food moves through the stomach, which is responsible for partial degradation of proteins. As the stomach is a very acidic environment, there are about 1000 times less microbes than in the mouth.

Then, food moves forward to the small intestine where degradation of macronutrients is finalized. Here the macro- and micronutrients also get absorbed to the bloodstream. The environment here is a lot friendlier than in the stomach, so it is home to about the same amount of microbes that live in the mouth.

However, the digestion is not finished in the small intestine. Food, or what’s left of it, moves forward to the large intestine. This is a perfect environment for microbes to live in. The food moves at a slower pace and it’s full of nutrients for microbes. Although most of the nutrients get absorbed already in the small intestine, there are compounds — the dietary fibers — that our own digestive enzymes are not able to degrade.

Fibers make their way to the end part of the large intestine — called colon. Here resides about 10 thousand more microbes than in the mouth and small intestine and more than million times more microbes than in the stomach. This is found to be the most densely and diversely inhabited part of the human body and most likely the highest microbial density recorded in any habitat on the Earth.

The microbes, living in our gut, compensate for what our own digestive enzymes cannot degrade. They help to increase the availability of energy from food. Without microbes we would get about 10–15% less energy from our diet.

But it’s not only energy. While degrading the fibers, gut microbes produce different molecules called metabolites that regulate essential functions in our body. For example, these metabolites strengthen the gut barrier — the only defence wall that prevents pathogenic microbes, toxins and other potentially harmful particles from entering the bloodstream and getting access inside our organism.

In addition, gut microbes produce vitamin K and group B vitamins, as well as modulate metabolism. It has been found that the gut microbiome composition differs between lean and obese individuals. This is well illustrated in studies conducted with mice who have been raised in completely sterile conditions so that they lack microbes. When transferring the gut microbiome of lean or obese human to such mice, then the mice quickly adopt the metabolic state similar to humans. Those getting the microbes from lean individual stay lean and those getting the microbes from obese person become obese.

Doesn’t it seem simple, that we could just get the microbes from lean people and become lean ourselves? Well, I’m afraid, I have to disappoint you. Yes, we could get a great push towards, but the food we eat influences who stays alive and permanently inhabits our gut.

Studies have shown that diet can make some shifts in the gut microbiome as quickly as 24 hours. However, to make a lasting change, you must eat a healthy diet consistently.

So, the communication between our gut microbes and digestion is two-way, as the gut microbes affect how our metabolism works and the food we eat affects the composition of that community living in the gut.

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Not long ago we used to think that a good bacteria is a dead bacteria. We’ve been scared of the microbes and tried to build up a safe sterile environment around us. However this is not exactly what nature has intended.

During the past decade it has become clear that we live in symbiosis with the microbes living on and inside us — our microbiome.

Already during birth we are coated with microbes. This is the seed to the formation of our very own microbiome. And our microbiome is one of the fundamental building blocks of our immune system.

About 80% of our immune system resides in the lining of your gut, and the microbiome is in constant contact with it. A healthy, resilient gut microbiome relies on high richness and biodiversity.

Richness is the total number of different bacterial species in your microbiome

Diversity is the amount of individual bacteria from each of the bacterial species present in your microbiome.

Let’s compare these two concepts in a group of 30 people with different professions. Richness would be the sum of all the different professions we have — e.g teacher, doctor, scientist, police and lawyer. Diversity on the other hand shows how many of these different occupations we have — let’s say 2 teachers, 1 doctor, 5 scientists, 2 police officers and 20 lawyers.

Well in this group of people, the richness can be high, but the diversity surely is not, as the vast majority of people are lawyers. And in case of some accident, we do have 1 doctor, but this could prove to be not enough.

A rich and diverse microbial community is much more capable and resilient. All of the different species carry about 2–20 million genes necessary for producing metabolites — small compounds that all regulate different functions in our body. Some of these compounds are responsible for vitamin production, some for digesting the food or communicating with the brain, immune system or responsible for other crucial functions in our body. The larger pool of these compounds we have, the better we are equipped to face different situations.

Secondly, a diverse community is more stable because it prevents the overgrowth of harmful pathogenic bacteria. Let’s imagine that instead of these 20 lawyers we have 20 burglars. It would be very difficult for our 2 policemen to fight against all of the burglars. And when we think of the microbes, they reproduce very quickly meaning that instead of 20 burglars we’ll soon have 40 of them, against maybe 3 or 4 policemen.

Scientists have found that low microbiome diversity can lead to various chronic illnesses — digestion problems, bowel disease like IBD, metabolic diseases like obesity and type II diabetes, neurological disorders like anxiety, depression, Parkinson’s disease, heart or kidney disease and many other illnesses.

As David Attenborough says in his latest movie “Biodiversity is the key to balanced nature. And species can only thrive if everything else around it is thriving.” This is also perfectly true for our microbiome. A healthy microbiome is a diverse community of microbes and this can be achieved only by enabling our microbes a good environment to live in.

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In upcoming stories we’re going to write more about how we can build up a healthy environment for our microbes. So, stay tuned to learn more about the importance of gut health and balanced microbiota.

We’re always waiting for your feedback. Let us know of your thoughts and questions. If you enjoyed reading this, make sure to click the “follow” button and check out our webpage www.elsavie.com

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Sources and interesting reading:

• Diversity, stability and resilience of the human gut microbiota (Nature 2013)
• Role of the gut microbiota in nutrition and health (BMJ 2018)
• The Human Superorganism: How the Microbiome Is Revolutionizing the Pursuit of a Healthy Life (by Rodney Dietert)
• Gut: the inside story of our body’s most under-rated organ (by Giulia Enders)