The Role of the Gut in Immune Protection and Reaction

By Dr. Susan Tanner, MD

In previous articles we have discussed things that are helpful for “gut immunity” but what does that mean?  Further, if an individual does not have any obvious gastrointestinal or digestive symptoms, like bloating, diarrhea, constipation, nausea, or food intolerances, it is easy to overlook the importance of this important organ and the many functions it performs.

What Exactly is the Gut?

The term “gut”, as we discuss it, pertains to the lining of the small intestine.  In basic biology and even in medical school physiology, the importance of this organ is greatly simplified and diminished.  In just a few words, the small intestine or gut is described as a conduit providing passage of ingested foods and liquids within a lining rich in blood flow that allows digested nutrients to be absorbed into the blood stream and carried to various organs. Food byproducts are then passed along into the colon for some water resorption and then passed out of the body in the form of fecal waste. The whole process sounds simple and straightforward, right?

If it is so simple, then why is the small intestine is such a long passage? In fact, the the small intestine is 32 feet in length, with the large intestine another 12 feet in length. That is a LOT of ground to cover! If the main function is absorption and most of that occurs in the first few feet of small intestine, then why have all this extra distance?

More Than Just Nutrient Absorption

The reality is that the lining of the gut does so much more, especially in the realm of the immune system and protecting our bodies from harmful invaders. For one thing, the action of “good” or beneficial bacteria on indigestible fiber produces more of a substance called “short chain fatty acids”.  Short chain fatty acids in and of themselves have many roles, including the production of lipids, energy, and vitamins. These supply all the organs of the body the power to function properly, including the healthy cells of the colon. They can also affect appetite! This is one reason why when the microbial diet in the gut is out of balance, one can feel bloated, low on energy, and have a greater appetite—your cells are just not getting what they need, so the body slows down and craves more food to make up the difference.  Short chain fatty acids also form a protective area around the production of SIgA, also known as secretory immunoglobulin A.  SIgA has many complex roles in the immune system, but its presence in the gut protects the mucous membrane from infections, viruses, and abnormal yeast overgrowth.

SIgA Dysregulation and Leaky Gut

Because the gut is so complex, however, the function of SIgA can become dysregulated.  It can actually become OVERSTIMULATED by certain toxins such as molds and chemicals.  When this happens, then the body becomes hypersensitized to many foods, odors, and chemicals.  You may have heard of a syndrome called “leaky gut”.  The term has absolutely nothing to do with bowel function but everything to do with immune function that initiates in the gut.  When a patient is experiencing symptoms of leaky gut, SIgA may be high or low, but the normal regulatory functions of natural killer cell production has decreased to the point that the activation of inflammatory cytokine production takes place. It sounds overly complicated, but this is why leaky gut sufferers experience sudden reactions and intolerances to foods that were previously well tolerated and frequently consumed. Once inflammation is triggered, a multitude of symptoms and pathologies can manifest, including more pronounced food allergies or hypersensitivities, autoimmune diseases not limited to the GI tract, and increased susceptibility to illnesses.

Immunity and the Gut

The full immunity of the gut can be caused by or impacted by many things. Some children are born with low levels of SIgA, and the determination of whether this is a familial condition or something that happened in utero or during childbirth must be investigated. We do know that many children with low SIgA levels suffer more with respiratory infections and chronic allergies, likely because the immune system is not as strong from the get-go.

In adults, there are several causes of immune issues with the gut.  These can include chronic physical or emotional stress, chronic infections, damage from certain medications, poor diet, and exposure to environmental toxins, such as mold, chemicals, or heavy metals.

Testing for Gut Immunity

When we have complex symptoms and problems with a patient, in general, looking at the gut can give some particularly good insight into the presence, or lack thereof, of general immune stability.  Again, this is where it all begins!

Testing for gut immunity, including SIgA can be done in several ways.  Blood levels can be tested, but it may not be a good indicator of what is being produced in the mucosal lining; thus, stool or saliva testing may be more reliable in these cases.

For Better Gut Immunity Start with the Basics

Trying to help yourself if you already know, or suspect, that your gut immune health may not be the best, should always start with going back to the basics again. For example, is your air clean and free of mold and chemicals?  You can test air and your surroundings, paying special attention to mycotoxin levels to make sure you are not being unknowingly exposed to dangerous toxins that molds produce.

Another question to consider: How is your diet?  Do you eat many processed or high-sugar foods and drinks? If your gut is not getting what it needs to keep your microbiota healthy and diverse but is bombarded with foods and drinks that foster things like bacterial and yeast overgrowth, your immune system will surely suffer. Dialing your diet in and centering the bulk of your sustenance around whole, organic vegetables, fruits, and meats is a good start.

Make sure to also consider any medications you are taking that have a side effect of lowering gut immunity or GI function in general?  For example, NSAID used CHRONICALLY lowers gut mucosa and thus decreases immune function. If you are not sure, ask your doctor for guidance and voice your concerns over long-term use of any drug and its impact on gut function and health.

An additional question that I ask all my patients, but that is not always considered by many people for its impact on gut immunity is, “Do you drink plenty of clean and purified water?” If you are chronically dehydrated, or are drinking tap water containing chlorine and fluoride, you are compromising your gut health and immunity. Think of it this way, if what you are drinking and cooking with was treated with chemicals designed to kill bacteria and other organisms found in municipal water supplies, then it is also doing quite a number on your gut!

Additional Tips for Building Gut Immunity

In non-complicated situations where there is not any other underlying disorder or pathology,  the use of plenty of dietary fiber and good probiotics, such as Klaire Pro 5 or OrthoMolecular Orthobiotic Plus may work be just fine as maintenance therapies. However, if you know your immune status is struggling, the addition of immune boosters or stabilizers may be helpful.  Sinus Defense, while its name implies use for just the sinuses, also has an incredibly positive benefit on the gut mucosa. The Transfer Factor proteins contained in the sublingual spray work to teach the body to regulate SIgA and to dampen inflammation when the body encounters environmental or pathogenic exposures.  Colostrum proteins, such as those contained ImmunoPRP from NUMedica (use practitioner code 40568) also work very well. These therapies can provide immediate help but may need to be continued for many months to recognize the full benefit. It is always important to remember, however, that no drug or nutritional supplement can take the place of good dietary habits and breathing clean air.