Our gut relies on nerves, muscles, enzymes, and neurotransmitters to properly digest food. While enzymes mainly break down our food, the nerves, muscles and neurotransmitters physically move the food through our digestive tract from the stomach to the small intestine and to the colon. When this happens in a healthy gut, bacteria gets passed through the digestive tract along with the food to its final destination in the colon. Problems arise when something interferes with this process.
Damage to the nerves or muscles in the gut can result in leftover bacteria in the small intestine, increasing your risk for SIBO. For example, diabetes mellitus and scleroderma can both affect the muscles in the gut, leaving room for SIBO to develop.
Physical obstructions in the gut, like scarring from surgeries or Crohn’s disease, can also cause an abnormal buildup of bacteria in the small intestine. Diverticuli, which are tiny pouches that can form in the wall of the small intestine, can also collect bacteria instead of passing it on to the colon, where it belongs.
There are also medications that influence or disrupt the normal gut flora, such as antibiotics, acid-blocking drugs, and steroids. And of course, as I mentioned above, the most common cause I see in my functional medicine clinic is from a diet high in sugar, refined carbohydrates and alcohol.