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Your Immune System is Mostly Gut Bacteria

author avatar Dr. Eric Berg 08/31/2023

To build a strong immune system, you’ve got to keep the friendly bacteria in your gut happy.

I can almost hear you thinking,

“Dr. Berg, have you lost your mind? What does my gut have to do with my immune system?”

Actually, nearly everything. Because 70 percent of your immune system is in your gut, making gut health - and, therefore, a strong immune system - of utmost importance. It’s May, 2020, and the coronavirus has caused a global pandemic.

I want you to understand how to strengthen your immune system, not just because of a frightening new viral illness, but to promote a long and healthy life.

Let’s take a look.

In this article, I’ll cover:

First, some basics about your gut microbiome.

an illustration of the human gut microbiome


What The Gut Microbiome Is

Your gut microbiome is the term given to the trillions of bacteria that live in and around your gastro-intestinal tract. That is, your gut. Your gut flora collectively are known as the gut microbiota.

These trillions of microbes are in a mutually beneficial relationship with you, their host. You give them a place to live. They give you immune protection and crucial nutrients, along with helping to regulate your blood sugars and other benefits.

There are over 10,000 species of bacteria in and around you. 99% of them are non-pathogenic. In other words, they won’t cause illness or disease. Most of them live in your large colon, just above and within the layer of mucous that lines the colon. A layer of colon cells is next, followed by a layer of immune cells - the gut lymphatic layer - that lies in wait for a pathogen to pop through so they can attack and kill it.


How Your Gut Microbiota Affect Your Immune System

When the flora, the microbiota in your gut, is imbalanced toward too many unfriendly microbes, you start to lose the lymphatic layer. Your immune system becomes compromised:

  • You lose lymph nodes.
  • Your antibodies decrease
  • Your T-cell production dwindles.

Let’s take a look at why these matter.

First, having a sufficient number of lymph nodes is critical, because they contain immune cells that stand ready to attack any bacteria, viruses, or other foreign substances that enter the body. If you have too few of them, you weaken your immune system.

Antibodies are another critical piece of your immune system. While they don’t kill microbes, they do put a tag on pathogens. Then, in the future, if those same kinds of pathogens invade your body, the antibody tag allows your immune cells to quickly identify the disease and kill the microbes that cause it.

Antibodies are specific to each pathogen. In other words, antibodies for the flu won’t give you immunity for COVID 19, and vice versa.

T-cells, short for thymus cells, are essentially trained by your thymus gland to properly carry out their immune function. The primary function of your thymus gland is something called central tolerance; that is, they thymus trains your T cells to recognize your own body cells that are beneficial to you.

a chalkboard sign that reads Boost Your Immune System

But sometimes this standard process goes off the rails. Let’s take a look at how central tolerance goes wrong.


How Autoimmune Diseases Start

If your T-cells didn’t have the knowledge of central tolerance as provided by your thymus, they wouldn’t be able to tell the difference between healthy, friendly bacteria and harmful ones. They’d end up killing both friendly and unfriendly microbes, thereby attacking your own body cells. This is how auto-immune diseases come about - your body mistakenly attacks its own tissue because it’s mistakenly tagged friendly tissue as unfriendly.

This process creates inflammation, which is the core of all auto-immune diseases such as Hashimoto’s, pulmonary fibrosis, and rheumatoid arthritis.

a word cloud for autoimmune disease

Because your gut microbiome is so heavily connected to your immune system, when the former is imbalanced, your immune function degrades, causing you to lose central tolerance. Your body can no longer cleanly differentiate harmful cells from friendly ones.

When T-cells are functioning correctly, they are able to differentiate between trillions of your own cells and invading pathogenic cells. As well, certain T-cells suppress inflammation. If your ability to combat inflammation degrades, you can end up with inflammatory conditions like cancer and diabetes in addition to the autoimmune diseases I already mentioned.

In my opinion, autoimmune diseases start in the gut. If you ever talk with someone who has an autoimmune disease - for example, Hashimoto’s, Crohn’s, lupos, or multiple sclerosis - they almost always have a gut problem.

That’s not the extent of what imbalanced gut flora can do to your health.


Other Ways An Imbalanced Gut Microbiome Affects Your Health

Without enough friendly gut bacteria, you get less of what are called short-chain fatty acids. One of these acids is called butyrate. Butyrate helps balance your blood sugars and improve Fat Storing Hormone resistance, and supports your immune system.

As well, an imbalance of gut bacteria lessens your ability to make critical nutrients such as:

As well, your body can’t make enough lactic acid, which contributes to an intestinal environment that is hostile to pathogens.

When you have an abundance of friendly bacteria taking up most of the space in your gut, they leave too little space for unfriendly bacteria. Which is a good thing!

Finally, a dearth of friendly bacteria also can weaken your intestinal barrier, or gut lining, leading to a condition called leaky gut.

A Note About Your Vulnerability To Coronavirus

With COVID 19, the disease caused by the coronavirus, the virus attacks your cells through a receptor located on your cells. The receptor is called ACE-2. Your gut has far more ACE-2 receptors than your lungs do, leaving you vulnerable to infection by the coronavirus.

I know that a lot of media focus has rightly been on your susceptibility to the virus through your respiratory system. I simply would like you to be aware that there’s more to the story than protecting only your respiratory system.

photo of a nurse holding a tube of blood labeled coronavirus


How To Supercharge Your Gut Microbiome

So, how can you supercharge your gut microbiome and make your immune system strong? I put together a video just on this topic, and I encourage you to take time to watch it. But in the meantime, I’ll give you a clue:

Intermittent fasting is an incredibly powerful tool for getting and keeping your gut microbiome in balance.

But I don’t want to give away too much; so, watch the video!

a hand lettered sign that reads Intermittent Fasting

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Disclaimer: Our educational content is not meant or intended for medical advice or treatment.

Editor’s Note: This post has been updated for quality and relevancy.

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