How Your Gut Affects Your Immune System…And Makes You Sick

by Dr. Anne Zauderer


Ever wonder what really happens to food after you eat it? It’s kind of a mystery how our body turns a delicious hamburger into, well, something not-so-delicious. Our food is our fuel. If our engines cannot properly burn that fuel, not only is it wasted, but even worse, it can also turn into something that is toxic to our body.

So what exactly is digestion?
Digestion, as defined by Merriam-Webster, is “the process by which food is changed to a simpler form after it is eaten.” Every step of digestion breaks our food down into smaller and smaller parts until it eventually gets to a form that the body recognizes and can use. So digestion actually begins in your mouth. Properly chewing your food begins the mechanical process of breaking the bonds that hold the proteins and complex carbohydrates together. Enzymes in your saliva catalyze the further breakdown of carbohydrates. The churning of the stomach and release of hydrochloric acid further breaks down the bonds that hold our food together so that by the time it (now called chyme) gets to your duodenum, it is ready to be picked apart so the body can conserve valuable nutrients and eliminate waste.

Improper digestion can appear as a myriad of symptoms including, but not limited to:

1. Bloating
2. Gas
3. Abnormal bowel movements
4. Systemic inflammation
5. Food sensitivities
6. Chronic joint pain
7. Eczema
8. Muscle aches
9. Chronic fatigue
10. Headaches

This whole process is highly coordinated and each step in the digestive process prepares the body for the next step. A few examples are:

1. The taste of bitter on the tongue stimulates the release of a hormone in the stomach called gastrin. Gastrin stimulates the release of acid in the stomach and prepares it for digestion of protein. (It is theorized that this reflex evolved as a self-protective mechanism because bitter foods in the wild tended to have a higher likelihood of being poisonous. It was advantageous to have the stomach acid to mitigate a poisonous effect.)

2. The taste of sweets on the tongue provides sensory information that stimulates the pancreas to release insulin before blood glucose levels begin to rise. This helps prepare the body and keep blood sugar more stable.

3. Stretch receptors in the stomach, when stimulated, cause an increase in motility of the colon. Termed the “gastrocolic reflex,” this reflex encourages the emptying of the colon in preparation for the food in the stomach. (Every new parent inadvertently knows about this reflex. Just think about the sheer number of diaper blow-outs that occurred right after your baby was done eating!)

We need food and water to survive. However, think about the risk we take every time we put something into our mouth. We are permitting something from the outside world to enter our body. Some of our sensory cues keep us from eating foods that could be harmful to us. Bad smelling, rotten food never seems appetizing. Oddly colored foods, like the indigo and blue family, do not exist much in nature (besides berries … which we have learned to be cautious of in the wild!). Dr. Seuss said it best, “I do not like green eggs and ham. I do not like them, Sam-I-Am.” There’s a lot of truth in this statement…eggs and ham are not supposed to be green!

Gastronomical Hazards

Our body’s first line of defense is the cells that line our digestive tract. These cells, called epithelial cells, provide a strong barrier against anything crossing into the bloodstream that our body doesn’t want there. Proteins cement these cells together; this is like building an impenetrable wall.

Our immune system makes up another one of our body’s defenses against outside invaders. It’s like an army that stands guard, ready to attack at the first sign of a foreign invader. With the thousands of viruses and bacteria we are exposed to in our world, we would not last a day without our immune system. Because of this risk, approximately 80% of our immune system surrounds the gut. It just makes sense to put the greatest number of guards around one of the most vulnerable areas in the body.

Where Our Gut Goes Wrong…


The foods we eat can bring outside “invaders” into our body. It is up to our immune system to fight them.

In a perfect world, our digestion would roll along and we would have no problems breaking down food and extracting the nutrients we need. Unfortunately, we don’t live in a perfect world.We live in a world riddled with pro-inflammatory foods (like sugar, wheat, and GMO grains) that are laced with preservatives and chemicals that all work collectively to tear up our digestive system.

Over time, these foods and chemicals chip away at our epithelial barrier and the proteins that hold those cells together. This leads to intestinal permeability, otherwise known as “leaky gut.” The result is that large compounds of undigested proteins penetrate our protective barrier and are not recognized by our immune system.So the underlying immune system in the gut attacks and flags these proteins as“invaders.” This begins a vicious cycle of intestinal inflammation and permeability.

Unfortunately, the story doesn’t end there. Once our epithelial barrier has been penetrated and an inflammatory cycle has begun, our gut immune system gets up-regulated and it can cause an explosion of intestinal inflammatory cytokines to be released into circulation. These inflammatory cytokines have been known to activate immune cells in the brain, joints, blood vessels, heart, and many other tissues. (This is the connection between eating certain foods and exacerbation of symptoms such as joint pain, headaches, brain fog, fatigue, etc.) However, one of the most sinister plot twists in this story is the fact that the dysregulation of our gut immune system over time can lead to an overactive immune response and eventually the body cannot recognize self from not-self and autoimmunity develops.

Sources of Leaky Gut:

1. Diet: gluten (wheat), casein (dairy), excess alcohol, excess sugar
2. Stress: increased cortisol
3. Infections: yeast (Candida), bacterial overgrowth, viral infection, parasite infection
4. Medications: antibiotics, acid blockers, corticosteroids
5. Hormones: decreased thyroid, decreased progesterone, decrease testosterone
6. Preservatives: MSG, food dyes, BHA/BHT
7. Nutrient Deficiencies

Self or Not Self?…Autoimmunity

As mentioned above, the immune system plays a critical role in defending our body against outside invaders. It is an incredibly complex system. New research is constantly revealing insights into how it functions. This is necessary because autoimmunity is a growing epidemic in our world today. As explained above, the gut plays a significant role in the development and management of autoimmune conditions.

Many diseases have an autoimmune component including: rheumatoid arthritis, celiac disease, type 1 diabetes, lupus, Hashimoto’s thyroiditis, Graves’ disease, and many more. It is the immune system’s inability to recognize what is part of the body and what is not. The immune system ends up attacking the body’s own tissue.

One quality of our immune system that makes it so effective is its ability to adapt to the outside environment. When exposed to new pathogens, the immune system has two major responses: the T-helper 1 (TH1) response and the T-helper 2 (TH2) response. These responses each activate different cells to fight pathogens in different ways. TH1 cells release macrophages, which are Pac Man-like cells that gobble up pathogens, isolate and then destroy them. TH2 cells mainly defend against extracellular pathogens. They stimulate the production of antibodies such as IgE and IgG that bind to mast cells, basophils, and eosinophils. This helps stimulate the body to rid itself of the microbe through coughing, sneezing, or diarrhea. Typically, in autoimmunity the balance of this system is thrown off and the body shifts to a TH1 or TH2 dominant state. To provide a check-and-balance in the body, we also have T-helper 3 (TH3) cells, otherwise known as regulatory cells. These cells down-regulate the immune system and maintain tolerance to self.

The key with the immune system is BALANCE. We need an immune response to protect us from invading pathogens, yet we need to keep the immune system in check so that it doesn’t attack our own cells. The good news is there are many ways you can help promote balance and support for the immune system:

1.Vitamin D—supports the regulatory TH3 cellsand helps maintain balance.
2.Glutathione—also supports regulatory TH3cells and helps maintain balance.
3. Turmeric (curcumin)—balances TH17 cells (which can also contribute to autoimmunity) and nuclear factor kappa-B (NF-kB) Which controls expression of genes that encode for pro-inflammatory cells.
4. Resveratrol—also helps to balance TH17 andNF-kB.
5. Repair the gut barrier—L-glutamine, probiotics, slippery elm, marshmallow extract, and digestive enzymes.