I told you in the first post in this series that as much as 80% of the immune system resides in the gut. I also said the gut microbiome influences your tolerance of some foods.  In the second post I said acid reflux could be caused by low stomach acid or even excess carbohydrates in the diet. This week we are going to look at the link between diet and the immune system.

Why is this important?

I mentioned in an earlier post how I’ve made it through a massive flu season without even catching a cold. Now, I know I’m not the only one; but there is some significance here.  Not everyone who escaped this year’s flu season unscathed has had their immune system and gut ravaged by chemotherapy. Chemotherapy targets rapidly dividing cells in the body.  Cancer cells are rapidly dividing cells, but so are the cells of the digestive tract. One of the main jobs of the gut is regulating immune function.  Chemotherapy also damages the bone marrow, which is responsible for producing red and white blood cells and platelets.  Depending on the extent of the damage, the patient may have trouble making blood cells again.  After my first treatment, I was hospitalized because I did not start making new white blood cells after they were wiped out.  Specifically we were looking at neutrophils, a type of white blood cell.  Neutrophils are like first responders in a crisis, but in their case the crisis is a fungus, bacteria or pathogen that is dangerous to the body. The neutrophils are set into motion to gobble them up.  They are a critical component of the immune system.

The gut is another place in the body where we have an army of bacteria living, or should have an army of bacteria living, that serve a similar function.  The diversity of this bacteria are directly related to the immune system’s ability to react appropriately to what passes through our gut.  That’s what we’re going to look at today.  Specifically, we are going to look at autoimmune and autoinflammatory diseases that are linked to the gut.  I have no way of knowing, after the fact, the extent of the damage done to my gut by chemotherapy, but by making strategic changes to diet and lifestyle I proved it is possible to rebuild the gut microbiome and my immune system.

The Immune System and Inflammation

What do I mean when I say the diversity of bacteria in the gut directly affects the immune system?  The immune system we are born with and the one we develop over time serve two different functions.  The immune system works like the fight or flight action of the sympathetic nervous system we discussed last week.  The system we are born with, the innate immune system, acts quickly to protect an open wound or destroy compromised cells that have become cancerous or invaded by a virus.  This system sets off a chain reaction with inflammatory cells that may increase blood flow (and white blood cells) to the damaged area, or raise the body temperature (a fever) to kill the virus. In this way, inflammation is good.  It tells us the body is doing what it is designed to do to protect itself.

The acquired immune system is the system that learns over time.  This may occur via the introduction of viruses through vaccines, general exposure when someone is contagious, or by other offenders that enter the system.  The adaptive immune system catalogs these offenders and pathogens for future reference.  When it is presented with them later, it will respond quickly with inflammation.  In fact, every antibody created by the immune system is specific to a particular foreign substance, like a lock and key.

So what is inflammation anyways?  Inflammation is the process used by the body in response to injury or infection, using the white blood cells of the immune system to identify, encapsulate and destroy any foreign material that may pose harm to the integrity of the system.  You will typically see redness and swelling when inflammation occurs, for example, when you have a cut or in the case of arthritis in the joints.  The suffix “itis” means inflammation.  Inflammation becomes a problem when it occurs too often, or chronically.

Autoimmune and Autoinflammatory Responses

When diversity of bacteria in the gut is low and the gut is out of balance (dysbiosis), the immune system is not, well, worldly.  It often overreacts to all foreign (not us) matter as dangerous and goes to battle.  This means much more inflammation than is necessary to keep us healthy.  Antibodies are made for healthy cells and tissues, which results in autoimmune and autoinflammatory conditions.

Autoimmune Diseases of the Gut

Autoimmune disease occurs when the adaptive immune system mistakes healthy body tissue as foreign, causing it to attack the healthy tissue.  The body can no longer differentiate between self and other.  The attack can occur on organs, joints or skin, leading to diseases like type 1 diabetes, rheumatoid arthritis, psoriasis and lupus.  Where the gut is concerned, the two main autoimmune conditions are celiac disease and type 1 diabetes.

The antigen (a toxin or other foreign substance that triggers an immune response in the body, producing antibodies) that enters through the gut, does so via the mucosal lining.  In order to get to the mucosal lining, there must be some permeability in the gut wall (commonly known as leaky gut, which we’ll cover in depth later).

Celiac disease occurs in individuals with antibodies for gluten and gliadin, two proteins found in wheat and other grains.  When these proteins hit the mucosal immune system, the body sees them as invaders and invokes an immune response (inflammation), creating antibodies.  Only 1 in 100 people have actual celiac disease.  Many others may just have a wheat allergy, gluten sensitivity or gluten intolerance, which aren’t as severe.  However, all can interfere with the absorption of nutrients in the diet due to damage done to the gut wall.

Type 1 diabetes typically develops in early childhood; which makes it so crucial to establish a healthy microbiome in the first couple years of life.  Development of a diverse microbiome is critical in infancy to long-term health.  When born naturally and breast-fed, a baby receives necessary exposure to a broad spectrum of good bacteria that will populate it’s immature microbiome.  Babies born via C-section have a higher risk of autism, allergies, obesity and celiac disease.

Type 1 diabetes is also associated with inflammation of the gut mucosa.  In type 1 diabetes, the body attacks the pancreas, preventing the pancreas from producing insulin, a hormone necessary for the absorption of sugar.  Without insulin, sugar (glucose) remains in the bloodstream instead of being absorbed into the cells for energy.  Insulin regulates the storage and usage of glucose in the body, like an on-demand system as the body needs glucose.  Type 1 diabetes is linked to gut dysbiosis; although we don’t know which came first.  Maintaining a healthy gut microbiome is one way to reduce the risk of developing type 1 diabetes.

We can see when the microbiome lacks in diversity, the adaptive immune system does not have a good teacher to teach it what is good and what is bad.  Diversity of the microbiome is important to a healthy, robust innate immune system.

Autoinflammatory Diseases of the Gut

This newer category of inflammation based diseases is due to a malfunction of the innate immune system.  The innate immune system is the primal immune system we are born with.  The most common diseases in this category are inflammatory bowel diseases (IBD): ulcerative colitis and Crohn’s disease.  Here, the immune system reacts in the absence of any antibodies or antigens.  Some environmental trigger sets off the innate immune system, causing inflammation in the gut.  The immune system attacks the intestinal lining and causes chronic inflammation in the intestinal wall.

Individuals with IBD tend to have a higher amount of pathogenic gut bacteria.  This dysbiosis in the gut can cause the immune system to mistake good bacteria for invaders.  Here again, diversity is key to maintaining a healthy gut microbiome and reducing risk for IBD.

Crohn’s disease is marked by an inflamed small intestine.  Less food gets digested and individuals tend to have more water in the colon.  Because of this, more often than not food is passed too quickly, and diarrhea is common.

Ulcerative colitis is marked by inflammation of the mucosal lining of the large intestine (colon and rectum).  Triggers include microbiome imbalance, stress or diet.

Individuals suffering from autoinflammatory diseases should consult with their doctor about anti-inflammatory diets designed to address dysbiosis and calm flare-ups.  At the very least, identification of foods that induce flare-ups and mineral deficiencies, as well as eliminating toxins, excess carbohydrates and refined sugars, unhealthy fats and processed foods, along with adequate hydration can go a long way to addressing symptoms of IBD.  As with all gut-related disorders, managing and reducing stress can improve the health of the gut and digestion.

What Does this Mean for You?

The goal today is to give you insight into the link between the gut, the immune system and how the immune system can be triggered either by diet or the balance of bacteria in the gut.  We’ve already looked at how to feed gut bacteria to improve the gut microbiome.  It’s important to point out that the diet information I provided above is not limited to autoinflammatory diseases.  Toxins, refined and processed foods, unhealthy fats that throw off our Omega 3 to Omega 6 intake, inadequate hydration with clean, filtered water, and failure to address stress level are linked to overall disease risk.  The diseases discussed above are merely examples the progression of disease if diet and lifestyle are not brought into alignment to address gut dysbiosis before it leads to larger health concerns.

I hope this information was helpful to you.  I’ll be back next week with another installment in gut health, where we will look at irritable bowel syndrome (IBS).

Yours in Wellness,

Jackie

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