SIBO (Small Intestinal Bacterial Overgrowth) Causes, Symptoms, Treatments, and Diet
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)
Dr. Anand received MBBS degree from Medical College Amritsar, University of Punjab. He completed his Internal Medicine residency at the Postgraduate Institute of medical Education and Research, Chandigarh, India. He was trained in the field of Gastroenterology and obtained the DPhil degree. Dr. Anand is board-certified in Internal Medicine and Gastroenterology.
- Small intestinal bacterial overgrowth (SIBO) definition and facts
- How does normal gut bacteria cause SIBO?
- Associated SIBO: Types of other diseases or conditions associated with it
- SIBO symptoms and signs
- Is there a test to diagnose the condition?
- Antibiotic and probiotic treatment for SIBO
- How can the condition be prevented?
- Does SIBO relapse? What's the prognosis?
- Find a local Gastroenterologist in your town
Small intestinal bacterial overgrowth (SIBO) definition and facts
- SIBO stands for small intestinal bacterial overgrowth.
- SIBO can be considered to be of two types. One is associated with identifiable diseases or conditions of the intestines. The other is not.
- SIBO of either type can give rise to similar symptoms including indigestion, diarrhea, bloating, abdominal pain, and diarrhea or loose stools.
- The type associated with intestinal diseases and conditions may result in, the inability of the body to absorb nutrients from the intestine and may lead to malnutrition and vitamin deficiencies that may help direct testing to find the diagnosis. This article deals only with SIBO associated with intestinal diseases and conditions.
- The diagnosis is often one of exclusion, making certain that other causes of the symptoms are not present.
- Blood tests, breathe tests, and biopsies or tissue samples from the small intestine may be required to make the diagnosis of either type of SIBO.
- Antibiotics may be prescribed but the type and length of treatment depends upon the patient and the symptoms.
- Any underlying illness will also need to be addressed at the same time once therapy is started for SIBO.
- The prognosis depends upon how well the associated illnesses are managed and the response to therapy. Relapse is fairly common.
How does normal gut bacteria cause SIBO?
The small intestine is a relatively clean place. The stomach receives food, mixes it with acid and digestive juices and turns it into a clean slurry that is pushed through the three parts of small intestine (duodenum, jejunum, ileum) where the nutrients are absorbed into the body. The refuse is dumped into the large intestine, or colon, where water is absorbed and the feces become more solid and are eliminated from the body.
The normal bacteria (flora) of the gut, perform important functions, helping to digest certain vitamins like folic acid and vitamin K, and they protect the intestine from being invaded by disease causing bacteria. However, if the normal function of the intestine is compromised, bacterial overgrowth may occur. This may be the result of a lack of adequate stomach acid, damage to the intestine by toxins like alcohol, or a decrease in the speed at which the small intestine transfers material to the colon.
The colon is not as clean as the small intestine and reflux, or backflow, of stool into the small intestine can colonize it with colonic bacteria.
This article will discuss only the type of SIBO associated with intestinal diseases and conditions.
Associated SIBO: Types of other diseases or conditions associated with it
Small intestine bowel overgrowth is often associated with another illness that affects the function of the small intestine. The body has many protective mechanisms to keep bacteria under control, including stomach acidity and intestinal motility, the ability for the intestine to move its contents downstream at an appropriate speed. Bacterial growth is hindered by the presence of bile and immunoglobulins. Finally, the ileocecal valve prevents stool from refluxing from the colon (large intestine) into the ileum or the last part of the small intestine.
Any illness or disease that affects the body's defense mechanism puts a person at risk for SIBO, but the majority of people develop SIBO because of a problem with intestinal anatomy or intestinal muscle. These may include abnormal anatomy of the intestines caused by surgery (gastric bypass surgery, bypassed intestine), bowel strictures and adhesions that can lead to intermittent bowel obstructions, diverticuli or outpouchings of the small intestine, and tumors. Bowel motility may be affected by neurologic diseases including myotonic dystrophy and Parkinson's disease and a rare condition called intestinal pseudoobstruction. People with diabetes with autonomic dysfunction (nerve damage) that affects intestinal muscle also may develop dysmotility.
Any illness or disease that affects the body's defense mechanism puts a person at risk for SIBO, but the majority of people develop SIBO because of an intestinal motility problem. These may include complications from gastric bypass surgery, bowel strictures and adhesions that can lead to intermittent bowel obstructions, diverticuli or outpouchings of the small intestine, and tumors. Bowel motility may be affected by neurologic diseases including myotonic dystrophy and Parkinson's disease, and a rare condition called intestinal pseudo-obstruction. People with diabetes with autonomic dysfunction (nerve damage) may also develop dysmotility.
Other intestinal diseases that may be associated with SIBO include:
- Crohn's disease
- Celiac disease
- Achlorhydria (chronic inflammation causes the stomach to become unable to produce acid)
- Cirrhosis of the liver
- Alcohol abuse
- Non-alcoholic steatohepatitis (NASH)
Next: SIBO symptoms and signs
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