• Dr. Juliet Ghodsian

SIBO: The Small but Mighty Intestine

The gastrointestinal tract is one of the most important systems in your body, a Pillar of your Health. The reason for this is the fact that so many other branches of your physiology are intimately and intricately connected to your digestive environment; its balance, integrity and optimal function.


In the context of my own journey with Crohn’s Disease the most important elements to review are the normal functions of your small and large intestine and their relationships with your immune system, nervous system, endocrine system and your personal microbiome.


The digestive process begins in the mouth, continues in the stomach and finalizes in the small intestine with the addition of enzymes from the pancreas and bile from the liver. Digestion, however, is only one function of the small intestine. I like to describe the small intestine as the House of Digestion and Immune Integrity. We often group the small and large bowel together as if they are one organ, the intestine. This is not the case at all. They are completely different anatomically and physiologically. The small intestine carries not only the responsibility for full and complete digestion of food and absorption of nutrients from that food, but also the important function of creating the foundation of your immune response. How?

The immune system that lives in your small intestine environment has the important job of determining what is good for you and what is not, what is food and what is waste. This is why I use the word Integrity. As you grow up, your immune cells learn in the small intestine how to distinguish between cells that belong to your body or could benefit your body, from cells that are a danger to you. It also provides the barrier between you and the outside world. This allows for careful selection and passage into your system only of items that benefit you, and the identification and elimination of items that could harm you. If this process is disrupted, you will have an immune system that is dysfunctional. For many patients this results in chronic inflammation, poor immune response to infections, or even auto-immunity.


We also know that there are receptors in the small intestine for neurotransmitters like Seratonin and Dopamine, which previously were considered to only act in the brain. We have revised our understanding to include the concept of a “Gut Brain” and the fact that your digestive environment is influenced by neurotransmitters, stress hormones like cortisol, and even vitamin D.

Suffice to say, it really is all connected.


Let’s review a few more details on the nervous system of the small intestine to help us understand why damage here could result in an inflammatory bowel disease. In the colon the nervous system serves to help you have a bowel movement and remove waste products. In the small bowel, the nervous system is primarily active in order to remove residues of food and bacteria from the small intestine into the large intestine. It does not necessarily trigger a “bowel movement”. This is important because some people think that if they have a bowel movement every day they couldn’t have anything wrong with their “intestinal movement” in the small intestine. Not true.

The nervous system in the small bowel has its own name:

The Migrating Motor Complex ( MMC).



We discussed how the MMC can be damaged in the post on Gastroenteritis and Post-Infectious IBS, so we will not go into detail here. The important piece to make note of is that almost all cases of Small Intestine Bacterial Overgrowth (SIBO) are the result of or have the secondary effect of disruption to the MMC of the small bowel. This causes ineffective cleaning and a resultant build-up of bacteria or fungus where it does not belong: in the small intestine.


Bacteria and Fungal overgrowth in the small bowel will result in several things:


Bacteria consume food items in the bowel and release gases

o Bloating and distention of the abdomen

o Pain

o Discomfort

o Over-fullness

o Burping

o Episodic diarrhea/loose stools

o Constipation


Disruption of digestive enzymes in the intestinal wall

o Maldigestion

o Gas production


Bile de-conjugation by bacteria

o This disrupts the ability of bile to help your absorb the fats in your diet and can lead to fat soluble vitamin deficiencies (Vitamin A, D, E,K)


Immune System Upset

o Activation of the immune response

o Chronic inflammation

o Leaky Gut Syndrome

o Food Allergies

o Autoimmunity

o etc...


When considering your own health and digestive balance, it is extremely important for you to think about the Small Intestine and whether or not you may be dealing with dysfunction in that part of your digestive tract and how it is potentially affecting your overall health. However, let us not forget that we are dealing with a whole person in a complicated stew of genetics, emotions and environmental factors. We need to consider all the details of infections, anatomy and physiology, but do not get lost in the details of the biomedical approach. Are you trying to see the forest for the trees? We are more than the sum of our anatomical parts. We must treat our whole self in order to truly heal.



Next up...Deep emotional healing. The Good, The Bad and The Ugly

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