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Your gut is a rainforest.  A rainforest is full of variety, variability, and species population numbers beyond our comprehension.  The rainforest is one of the most diverse and stable ecosystems we know of and houses species we haven’t even discovered yet.  That is exactly how our gut is when it comes to the bacteria living in it, writes Brian Bishop.

As Dr. Justin Sonnenburg, Ph.D, an associate professor of microbiology and immunology at Stanford and Dr. Erica Sonnenburg, Ph.D, a senior scientist in the Sonnenburg Labs, discuss with the host of FoundMyFitness, Rhonda Patrick, Ph.D in the  Youtube video ‘How The Gut Microbiota Affects Our Health with Dr. Erica & Dr. Justin Sonnenburg’, there are 10 times more bacterial cells associated with our bodies than human cells and 100 times more bacterial genes associated with our collective genome than human genes.  Meaning? Yep, you guessed it.  We are more microbial than human!  Therefore, this complex and dynamic ecosystem of bacteria that makes up so much of us is connected to every aspect of our biology.    

As we take a dive into the biome of our guts, we see that the gut microbiota is a population of beneficial and symbiotic bacteria, as well as pathogenic microorganisms that literally share our body space.  It is not only a community, it is a microbial organ that is extraordinarily important and is connected to almost every piece and part of our health.  This organ holds the key to the health of our immune systems, metabolism, and, due to the brain-gut axis, can dictate our moods and behavior.

To explain the gut-brain axis (GBA), this is the communication between the gut and the brain.  This communication goes both ways and links the lower gut with the emotional and cognitive centers of the brain through messages sent chemically.  

So, that’s a pretty big deal, which I will explain.

These interactions affect our mental capabilities, our ability to manage and cope with pain, and determine if we will be afflicted with anxiety, depression, and neurodegenerative diseases.    

So where exactly is this rainforest of bacteria harboring in our body?  

Well, most of the bacteria associated with our gut live in the distal part of our large intestine, which means they hang out in the colon.  The interesting thing here is that the gastrointestinal (GI) tract also has the most amounts of immune cells.  

Why is that important?  

Just as the gut microbes interact with the brain in the GBA, the gut bacteria also interacts, a lot, with the immune cells.  Before studying the gut biome we believed that gut bacteria and immune cells didn’t get along, which is pretty easy to see why.  

The job of immune cells is to keep us from getting sick by ridding our bodies of foreign invaders, like bacteria.  

However, when it comes to these little living beings of our guts, the immune cells talk to them all day long.  This constant interaction regulates how our immune system functions.  Since immune cells leave the gut and go all through the body, they naturally affect the whole body’s immune function, including respiratory function, vaccine response, and autoimmune disease manifestation.

That’s not all…

Over the past decade we have learned a great deal more about the gut microbial community of our colon.  In learning the importance and function of the gut biome we have learned that our diet has a huge impact on it. What we choose to eat directly influences this microbial community which in turn has a huge impact on our biology.  

Let me repeat that as it is important.

What we choose to eat directly influences this microbial community which in turn has a huge impact on our biology.  

To put it even more plainly, we have the ability to control our physical health, mental well-being, and even some gene expression through diet, by way of these gut bacteria.  Therefore, we need to feed them, and feed them the right stuff.

How can you actually use this important fact?

Dietary fibers, which are complex carbohydrates, are the essential food for feeding the gut microbiota. Our bodies do not digest complex carbs well, which is a good thing, because it means that this fiber makes it to the colon to feed our gut bacteria.  When the fiber reaches the bacteria, they metabolize it and change it into Short-Chain Fatty Acids (SCFAs) such as butyric acid, propionic acid, acetic acid, and lactic acid. SCFAs are also called Volatile Fatty Acids (VFA) and are produced when dietary fiber is fermented in the colon and primarily absorbed through the portal vein (the vein that goes from the GI tract to the liver) during fat digestion.  

And here is your gross out fun fact for the day: these SCFAs are actually the bacterial wastes (aka microbe poop) that we absorb.  

Nice thought, huh?

Well to help you deal with that thought here is another.  

We need those SCFAs because they provide signals to regulate our immune function, whether it is to heighten or suppress it.  

For a quick trip down the proverbial rabbit hole, here is some information on our immune system response.  

A component of the immune system is that it suppresses the responses of other cells.  With SCFA signaling we can increase the number of T-regulatory cells (T-cells or Tregs).  The T-cells can suppress cell response.  By doing this it creates a built-in self-check to prevent excessive reactions.  Without this self-check, our bodies would go haywire and continually attack itself.  

Inflammation anyone?

Yes, inflammation is often the effect of when our bodies are not functioning properly, but why is this important?  

Operating your body in a high inflammatory state can lead to the development of chronic diseases, such as asthma, heart disease, cancer, metabolic syndrome, allergies, and autoimmune disorders.  Plus inflammation drives aging, and I don’t mean the accumulation of wisdom, in fact, it can bring about cognitive decline.

This is especially worrisome in our westernized culture. We often live stressful lives with little physical activity and a diet full of the wrong kind of fats, processed simple carbohydrates and simple sugars.  

Why does it matter that we live and eat this way?  

With western diets loaded with simple carbohydrates, such as highly refined grains and processed/packaged foods, we begin a detrimental process that is harmful to our much-needed gut biome.  Simple sugars are absorbed in the upper GI, so therefore the bacteria, which live all the way down in our colon, are simply starving.  

Without the aforementioned intake and fermentation of dietary fibers, we cannot feed our gut bacteria.

So to sum that up: No dietary fiber = No SCFAs = inflammation = chronic disease.  

Got it?

Words by Brian Bishop. Part two of this article is coming soon.