Self-Care for Your Body’s Immunity Protectors: Gut, Lung, Skin + Blood-Brain Barriers

Self-Care for Your Body’s Immunity Protectors: Gut, Lung, Skin + Blood-Brain Barriers

In This Article

Gut, Lung, Skin + Blood Brain Barriers

How does our body protect us? There are four main defense systems—read on to learn what they are and how to use them to your advantage!

Early studies from the University of San Diego, published in the prestigious journal Nature, evaluated over 18,000 microbial samples of 33 types of cancers from over 10,000 patients. This research may be years away from FDA approval, but the results are remarkable. The research team found a strong microbial signature for each of the 33 types of tumor cells they evaluated. In other words, each type of cancer studied was highly correlated with a unique population of certain microbes.11

The body is equipped with four protective barriers to keep naturally occurring bacteria from migrating willy-nilly.

I will help you understand the roles of the body’s four barriers and how we should be supporting their function.

Why do we need microbial barriers?

Each year, we dump four billion pounds of toxic chemicals into the American environment. Seventy-two million of these chemicals are cancer-causing. Monsanto’s product Roundup, or glyphosate—a pesticide that kills our beneficial microbes—has found its way into even our organic foods and rainwater. There is mercury residue on the organic vegetables we eat from the coal-fired power plant emissions that cover America.6 Needless to say, our bodies need help!

Thankfully, the human body has evolved to protect itself from toxic exposure, opportunistic bacteria, fungi, viruses, and other pathogens poised to take advantage of broken down or worn out immune barriers.

Meet the four barriers!

The body has evolved protective barriers to make sure enemy microbes and toxins do not infiltrate beyond our immune system. When these barriers break down, the body’s primary defenses and immunity are weakened. This can cause accelerated aging, degeneration, and increased risk of disease.

On the other side of these four epithelial barriers are immune-carrying lymphatics, ready to pounce on any toxin or pathogen that tries to penetrate these barriers. The collecting ducts of the lymph are able to detoxify each of these barriers effectively. This is one reason why the lymphatic system is so important—each of the four barriers heavily depend on clean and efficient lymphatic drainage.

If the barriers become compromised due to air pollution, digestive distress, or a multitude of other stressors, toxins will enter the intestinal lymphatics—eventually and systematically congesting the lymphatic system that protects all four barriers.

The 4 Barriers

  1. The Gut & Intestinal Barrier
  2. The Lung Barrier
  3. The Skin Barrier
  4. The Blood-Brain and CSF-Brain Barrier

The Gut + Intestinal Barrier

This is the largest barrier in our body, averaging out to the size of a tennis court! It is perhaps the most important, as all other barriers depend on the health of the intestinal wall as a protective barrier. The intestinal lining is made up of epithelium, blood vessels, lymph-collecting ducts, and beneficial microbes. These all depend on the health of this barrier.

Weak digestion can be caused by stress, processed, and pesticide-laden comfort foods, or extreme diets. These triggers allow proteins and fats to go undigested into the intestines. These undigested proteins and fats are too big to be absorbed into the bloodstream, and they end up being caught in the lymph-collecting ducts. Here, they can overwhelm the lymph and compromise immunity.

Eighty percent of the body’s immune system is located where the intestinal tract meets the lymphatic vessels. When the gut and intestinal barrier fails, toxins and pathogenic microbes can enter the blood via the lymph. Once in the blood, they slowly begin to disrupt and break down the remaining three barriers.1

Read More about The Gut + Intestinal Barrier

The Lung Barrier

The average person breathes 29,000 times a day. The quality of the air you breathe is of great importance.

A new study found an abundance of microscopic magnetite particles in samples of brain tissue from people in cities with high levels of air pollution.2 Magnetite is the highly oxidative, degenerative, and magnetic form of iron oxide.

Magnetite particles have been directly linked to brain degeneration and cognitive decline.7 Abnormal accumulation of metals in the brain is a key indication of Alzheimer’s disease. Thus, air pollution is being researched as a smoking gun for this currently irreversible disease.

The respiratory tract and lungs are lined with very delicate skin, or epithelium. An excess amount of air pollution from cars, cigarettes, solvents, synthetic clothes, and fire retardants in furniture constantly bombard the respiratory lung barrier.

Read More about The Lung Barrier

We recommend "DIY Immunity Ghee Tea":

Skin Barrier

The skin epithelium is a protective barrier supported by its own microbiome. Microbes feed on the natural oils produced by the skin, such as sebum. Sebum softens, lubricates, and protects the skin, preventing it from aging prematurely. Beneath the skin is an immune layer called skin-associated lymphatic tissue (SALT), which offers additional immune protection to the skin.4

Excessive washing with harsh soaps, chemical additives in lotions, and environmental exposure can compromise the skin’s role as a protective barrier.

Our skin, however, is very intelligent. It has evolved from primitive cell membranes that wrapped and sealed the inner contents of the cells. As early cells begin to group together, cell membranes become the protective layer of skin that group and wrap these communities of cells. We know these communities as organisms.

If the protective skin or epithelial layer was breached, the organism would be at risk of death. Interestingly, if the nucleus of any of these cells is removed, the cell will continue to live, suggesting that the “brain” of the cell is not the nucleus, as once thought, but in the cell membrane!5

The cell membrane acts as a sort of “awareness” membrane, communicating details about the outside world with the internal environment of the cell. Primitive survival depended on awareness of the changing environment: light/dark cycles, threats, invaders, and more.

The appropriate response to these changes and threats is made via the cell membrane, which has evolved into our skin.5

To this day, the skin is still our first line of defense from outside invaders. It transports information across the barriers about the changing environment and potential threats to our genes, brain, and CNS.5

Read More about The Skin Barrier

Learn about Ayurvedic Skin Health

Blood-Brain Barrier

The blood-brain barrier lies between the endothelium cells (which line the arteries and capillaries) and feeds the brain with nutrients and oxygen. When the body is inflamed, the junctions of the brain capillaries can become weak and break down, and toxins can find their way into the brain.3

The CNS glymphatic system drains three pounds of toxins from the brain each year during sleep.8,9 As blood flows into the brain, it concentrates in a plexus of blood vessels called the choroid plexus. In the choroid plexus, blood in the arteries is pushed into numerous villi or epithelial cells, forcing plasma or lymph fluid into the brain ventricles. Once the plasma or brain lymph crosses this barrier, it is called cerebral spinal fluid (CSF).

Studies show numerous toxins and heavy metals, such as mercury, arsenic, cadmium, and others, can build up and damage the epithelium of the choroid plexus, causing it to leak toxins into the brain chemistry.3

The CSF acts like a washing fluid rinsing the brain through its ventricles. As it washes, the brain picks up toxic particles, plaque, chemicals, bacteria, and viruses that may have slipped through the blood-brain barrier. These toxins are then reabsorbed through the brain’s glymphatic system.

We recommend "Best Ways to Detox Your Brain + Cerebrospinal Fluid":

Support for the Blood-Brain Barrier

Conclusion: Self-Care for the Body’s Protectors

The skin of the body was our first evolutionary barrier—it lines our digestive tract from top to bottom. Today, this is our first line of defense, and the frontline of interpreting the biochemistry of the world. When this barrier breaks down, not only do we experience digestive distress, but toxins can infect, congest, or inflame any of the other three barriers. For this reason, I have written many articles and my book Eat Wheat on how to reboot and strengthen digestion, support the intestinal skin and microbiome, decongest the lymphatic system, and reset the body’s natural ability to detoxify.

I encourage you to learn more about these very important processes in the body and remove obstacles to optimal health and longevity.

Remember, self-care is the new health care!

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Dr. John


  5. Lipton, B. The Biology of Belief: Unleashing the Power of Consciousness, Matter, and Miracles.

6 thoughts on “Self-Care for Your Body’s Immunity Protectors: Gut, Lung, Skin + Blood-Brain Barriers”

  1. Thank you Dr. Douillard for your cohesive concise overview of our Immune system…it is indeed an expression of divine intelligence.

  2. I love how you can explain complicated ideas from Ayurveda, modern science, and naturopathic medicine in ways that regular people like most of us without medical degrees can understand. Thanks for what you do.
    John S

  3. You attempt to mention all of the major pollutants but one of the biggest is always left out, the aluminum (and other toxicants) from geoengineering. These are in our soil, groundwater and the air we breathe. I watch it happen in the sky almost daily here in the Colorado mountains and wish you would also address this issue.

    • Hi Amber,

      Dr. John has written on toxicants like that. It is a much larger discussion and is one of the main reasons Dr. John believes we need to cleanse seasonally to encourage our bodies to cleanse out the pollution that infects our organic foods, water and air.

      Here are a few of this other articles discussing the numerous aspects of pollution and how it affects us:

      LifeSpa Staff


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