Explaining Small Intestinal Bacterial Overgrowth or SIBO and Its Connection to Chronic and Environmental Illness

by Dr. Susan Tanner, MD

SIBO, or Small intestinal bacterial overgrowth, has been an underlying condition for many inflammatory or autoimmune conditions for many years but is being recognized and diagnosed only in recent times by the general medical community.   To understand SIBO in simple terms, the gut, which as we have discussed in previous articles, is the lining of the small intestine. This lining has immense impact on the immune system in general, and for proper function, it requires the presence and activity of trillions of beneficial bacteria. Collectively, these are referred to as the “microbiome.” The activity of these bacteria creates the production of Secretory Immunoglobulin A, which is the starting point of the immune system. They also produce short-chain fatty acids which help form a barrier to the intestinal lining, preventing damage and allowing for better and more appropriate nutrient absorption. The microbiome also protects against opportunistic infections in the GI tract and beyond.

What is SIBO?

When these helpful bacteria are reduced in number and/or are replaced by non-beneficial bacteria, then a cascade of consequences occur which can impact the body from top to toe, giving rise to the term, small intestinal bacterial overgrowth (SIBO). What comes as a surprise to many is that this condition may or may not present as digestive symptoms or complaints. Thus, the GI tract is not always suspected as the place of origin for many of the systemic symptoms of SIBO. Such symptoms can range from joint and connective tissue problems to neurological and psychiatric-type concerns, to even skin problems. It is not a stretch to say that “health all begins in the gut.” To that point, any chronic health condition evaluation should include a look at the microbiome of the small intestine.

Causes for SIBO

While SIBO has likely been around for ages, the increased incidence of its occurrence can be linked to a number of factors that have evolved in more recent times. Some of the most likely causes come from the modern diet of overly processed foods, decreases in daily intake of fiber, and the drastic increase of sugar intake through food and drink. Additionally, the wide-spread use of systemic antibiotics kills off the normal gut bacteria, allowing the overgrowth of opportunistic non-beneficial flora. One of these bacteria is in the family clostridia.

Clostridium Difficile (C. Diff) and SIBO

In its most acute and virulent form, Clostridium difficile, or C. diff, causes dramatic abdominal pain, inflammation of the colon, cramping, and profuse, watery diarrhea. Because C. diff has heat resistant spores, it can be transmitted from one person to another easily and can remain alive on surfaces for long periods of time. While healthier people don’t usually display the intense gastrointestinal symptoms normally associated with C. diff, the seemingly dormant opportunistic bacteria are still at work creating havoc in the small intestine. Besides knocking down the good bacteria and their function, clostridia produce certain acids and toxins as they reproduce. Some of these are HPHPA, 4-cresol, and 4-hydroxyphenol lactate. Not only do these toxins destroy cells, produce patches (plaques) of inflammatory cells and decaying cellular debris inside the colon, and cause watery diarrhea, they also have the ability to interact with brain chemistry in the build-up and break down of neurotransmitters, particularly dopamine. Interestingly, patients presenting with depression, Obsessive Compulsive Disorder, Tourette’s syndrome, chronic fatigue, and autism often have high levels of dopamine as a result of bacterial overgrowth disrupting their microbiomes and secreting destructive toxins inside their bodies. Because excessive dopamine may also deplete glutathione in the brain, the tissues then become more susceptible to the build-up of other toxic chemicals—a damaging cycle of events. (Nature Reviews Neuroscience, AOP, Published September, 2012). (CELL.com: Microbiota Modulate Behavioral and Physiological Abnormalities Associated with Neurodevelopmental Disorders, Elaine Hsiao, December 5, 2013).

SIBO and Yeast Overgrowth

Another huge culprit in the SIBO group is yeast, especially candida yeast, which we have referred to several times in previous articles. Like clostridia, yeast may grow out of control due to antibiotic use, poor diet, and stress. (Stress also increases cortisol in the body which decreases the immune lining of the gut). Besides the aforementioned effects of imbalanced flora including GI symptoms and food allergies, yeast overgrowth can cause the formation of biofilm, a topic for future discussion. (Note: Biofilm is a slime-enclosed community of bacterial or fungal colonies that is very difficult to treat, even with the most powerful antibiotics or antifungals. Biofilms are held together by a matrix produced by the bacteria and fungi themselves. Within this matrix, the organisms communicate by chemical messengers, and generate proteins including enzymes that protect them from eradication—adapted from the Collins Dictionary of Medicine.) Additionally, the production of quinolinic acid—an endogenous neurotoxin—is evidence of yeast overgrowth impacting the neurotransmitter, serotonin. The resultant symptoms often present are sleep disorders, depression, muscle twitching, headaches, and impaired memory.

Moldy Indoor Environments and the SIBO Connection

Our SIBO discussion would be incomplete if we did not mention the role of inhaled or ingested mold and their impact on the gut. If you are living with mold in your surroundings, the constant bombardment of the mycotoxins from these molds can fragment the DNA of the T-lymphocytes, reducing white blood cell counts, and thus inducing immune suppression. When the immune system is down, more and more opportunistic yeast and bacteria can grow, and chronic health problems quickly arise. Mold spores can also live quite well in the lining of the gut wall where they can continue their damaging effects until eradicated.

Getting a Correct SIBO Diagnosis

In traditional medical settings, the gold standard for SIBO diagnosis is a breath test. As certain gases are released by microbes, these can be detected by measuring controlled samples of the breath into tubes. Certainly, this can give some indication as to the presence of the problem but the limitations are that it cannot accurately show what the microbes are, and treatment cannot be specifically directed. Most SIBO patients are given antibiotics to kill off the anaerobic bacteria for two weeks, occasionally accompanied by an immune-boosting treatment for the gut wall. It is then assumed that the problem is “cured” after a few weeks of treatment. Unfortunately, this is not the case in most individuals, especially if particularly resistant bacteria are present, if there is yeast overgrowth (not detected by breath test), or if there are mycotoxins present.

My preferred testing for SIBO is from urinary organic acids. This is a simple collection of first morning urine, but the results are very enlightening. By detecting acids secreted by the yeast and bacteria and cleared through the urine, identification of the symptom-causing culprits is much simpler. Once we know what we are dealing with, then an individual treatment plan can be safely devised. This is also a much easier test to do on children or the mentally infirm, and generally much less costly as well.

Once a diagnosis is made, treatments usually include both natural and prescription products, and immune builders. Diet and environment, two of the leading factors that cause SIBO must not be overlooked, though. I encourage my patients to test their homes for mold and to “clean” their diets of processed foods and excess sugars as equally important—possibly the most important—parts of their treatment. As in many previous articles, in order to get well, you must have “clean air, clean water, clean food.”

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