The Gut-Immune System Connection

With the current pandemic, people are looking for natural ways to optimize their immune system. Much has been written on the importance of a healthy diet, proper sleep, regular exercise, stress reduction techniques, and immune-enhancing supplements. All of these categories are important; however, there is another whole area of health that accounts for the highest percentage of the immune system—that is, the gut.
The small intestine is where approximately 70% of your immune system originates in tissues known as the Gut-Associated-Lymphoid-Tissue (GALT). The GALT is lymphoid tissue that consists of various immune cells that protect the body from foreign invaders. Therefore, if you have a healthy small intestine, you will have a healthier immune system!
Foods such as carbohydrates, proteins, and fats must be broken down properly before it can be adequately absorbed by the small intestine. This includes salivary enzymes during chewing, hydrochloric acid and pepsin by the stomach, bile from the liver and gallbladder, and digestive enzymes from the pancreas. The small intestine also absorbs water and nutrients. In contrast, the large intestine can absorb water but few nutrients.
Many people with chronic digestive problems, food sensitivities, those with acute and chronic health problems, and people under chronic high stress often do not digest food properly before having the potential for small intestine absorption. Improperly digested foods create problems with small intestine absorption and cause irritation and inflammation of the small intestine lining.
The small intestine mucosal lining is composed of unique folds and projections known as villi. The combination of these folds increases the absorptive area by approximately 1000 fold. This makes the small intestine’s total space equivalent to the surface area of a tennis court! The thin surface of cells that line the villi allows for the absorption of nutrients into a network of capillaries and lymphatic vessels to be distributed throughout the body. In addition, there is a regulated system of absorption between small intestine cells. There is a physical barrier between the cells of the small intestine, which includes tight junctions. These tight junctions also function to regulate what passes through and control the permeability of what is known as paracellular pathways.
There has been a great deal of research on the alteration of small intestinal permeability in patients with celiac disease, irritable bowel syndrome diarrhea type (D-IBS), inflammatory bowel disease (IBD), autoimmune disease, obesity, Type 1 diabetes, and non-alcoholic fatty liver disease. Essentially, researchers have found that unhealthy inflammatory changes in the lining of the small intestine result in the absorption of contents into the bloodstream that would not usually be absorbed. This results in the activation of the immune system and increased inflammation of the small intestine lining. Keep in mind that unhealthy changes in the small intestine commonly occur in people without celiac disease and irritable bowel syndrome.
You may have heard of the term “leaky gut syndrome.” This is a slang word that refers to increased intestinal permeability. The natural barrier of the small intestine is designed to prevent bacteria, yeast, and other microbes, as well as undigested food particles, from entering the bloodstream. Once these foreign particles come into contact with the small intestine, and even more so upon entering the bloodstream, the immune system responds to attack the intruders. As a result of the immune response, there is an increased inflammation that can cause many systemic symptoms and immune dysregulation.
Common Causes of Leaky Gut
*Pain medications
* Antibiotic use
* Standard American Diet
* High-stress environment
*Undiagnosed intestinal infections
* Gluten allergy
* Food sensitivities
* Nutritional deficiencies
* Chronic illnesses
I commonly find patients with chronic gut and immune system problems to have an undiagnosed infection in their digestive tract. These infections may include yeast overgrowth (such as Candida), parasites, or various bacteria. A newer generation stool test can help identify these infections so that they can be treated and cleared.
Following are 7 Steps To A Healthy Gut that most everyone can follow to improve their small intestine health.


7 Steps To A Healthy Gut
  1. Consume a diet low in common food sensitivities such as gluten and dairy. It is also helpful to complete food sensitivity testing with a holistic doctor. We commonly use this type of testing with patients to help expedite the discovery of problematic foods.
  2. Consume an anti-inflammatory diet, such as a modified Mediterranean Diet (reduced grains).
  3. Consume foods shown to benefit the health of the tight junctions between intestinal cells. There have been specific research showing benefit for intestinal cell health with quercetin rich foods. Examples include apples, grapes, onions, broccoli, citrus fruits, green tea, kale, and blueberries. Quercetin supplements are also available. Also, curcumin, as found in the spice turmeric, has also been shown in research to promote healthy intestinal permeability.
  4. Consume cultured and fermented foods rich in probiotics, which contain beneficial bacteria for intestinal health. Examples include yogurt (non-dairy forms are available), sauerkraut, kombucha (low sugar versions), kefir, tempeh, miso, and kimchi.
  5. Supplement with a probiotic that has human studied strains.
  6. Supplement digestive enzymes with meals for two months to optimize digestive function and allow intestinal healing.
  7. Supplement with food-grade aloe liquid or powder along with deglycyrrhizinated licorice (DGL) twice daily or two months for intestinal healing.
While many Americans have increased intestinal permeability, the good news is that it can be healed. You actually have stem cells in the small intestine lining that function to form new healthy cells. However, you must provide the environment for healthy cell turnover to take place and maintain its new health status. The recommendations in this article will go a long way in improving your absorption status and immune system function.
Hall, John E. Guyton and Hall Textbook of Medical Physiology E-Book (Guyton Physiology) (Elsevier) Health Sciences. Kindle Edition.
Lee, B., Moon, K. M., & Kim, C. Y. (2018). Tight Junction in the Intestinal Epithelium: Its Association with Diseases and Regulation by Phytochemicals. Journal of immunology research2018, 2645465.
Linsalata, M., Riezzo, G., D’Attoma, B., Clemente, C., Orlando, A., & Russo, F. (2018). Noninvasive biomarkers of gut barrier function identify two subtypes of patients suffering from diarrhoea predominant-IBS: a case-control study. BMC gastroenterology18(1), 167.
Wells J, Brummer R, Derrien M et al. Homeostasis of the gut barrier and potential biomarkers. American Journal of Physiology-Gastrointestinal and Liver Physiology. 2017;312(3):G171-G193. doi:10.1152/ajpgi.00048.2015