Small Intestinal Bacterial Overgrowth | Loyola Medicine

Small Intestinal Bacterial Overgrowth

Overview and Facts about Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth (SIBO) is the overgrowth of bacteria in the small intestine. While the small intestine always has a modest number of bacteria, excessive amounts of bacteria in the small intestine can cause malnutrition as your body competes with the bacteria for nutrients.

As the overgrown bacteria overly metabolize (break down) nutrients in the small intestine, an overproduction of metabolic byproducts or waste chemicals may irritate or damage the lining of the small intestine. If the lining of your small intestine is damaged, nutrient absorption and digestive health can be compromised.

Symptoms and Signs of Small Intestinal Bacterial Overgrowth

Signs and symptoms of SIBO are not well characterized; however, common symptoms include abdominal pain, fullness, and distention, bloating, and diarrhea. Excessive gas and bloating may be due to the overgrowth of hydrogen gas-producing bacteria or excessive microbial fermentation in the small intestine. Other symptoms of SIBO may include unexplained weight loss and/or a fatty stool.

In severe cases, SIBO can lead to complications that include:

  • Dehydration
  • Bone loss
  • Vitamin deficiency that can cause excessive bleeding
  • Low red blood cell counts

Causes and Risk Factors of Small Intestinal Bacterial Overgrowth

If you consume large amounts of refined sugars or carbohydrates, you could be at risk of developing SIBO. Certain conditions may also increase your risk of SIBO.

These conditions include:

  • Side effects of Crohn's disease or surgery that causes blockages in or shortening of the small intestine
  • Immunodeficiency or a weakened immune system
  • Small bowel diverticulosis, which is a condition that causes the growth of small sacs in the inner lining of the intestine that encourage bacterial overgrowth
  • Billroth II type of stomach removal, which creates a loop in the small intestine that houses bacterial overgrowth

Tests and Diagnosis of Small Intestinal Bacterial Overgrowth

Fluid from the small intestine tissue may be sampled to grow and identify the type of bacteria present in the small intestine tissue in a laboratory. Breathing tests are also used to confirm the presence of certain chemicals in the small intestine, which may indicate the type of bacteria living in the small intestine.

The presence of SIBO may also be suspected by measuring:

  • Blood cell or platelet count
  • The amount of fat in the stool
  • Blood chemistry

Treatment and Care for Small Intestinal Bacterial Overgrowth

To treat SIBO, it is important to first identify the cause of the SIBO. For instance, a diet low in carbohydrates may help reduce the overgrowth of carbohydrate-loving bacteria in the small intestine. Antibiotic treatment may also be implemented to restore the balance of healthy bacteria in the small intestine and provide symptom relief. In severe cases of malnourishment, fluid and nutrients may be administered intravenously (IV).