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Small Intestinal Bacterial Overgrowth (SIBO)
Overview
- What is SIBO?
Healthy intestines normally have many types of bacteria. In SIBO, the bacteria living in your small intestine are out of balance and are causing GI symptoms. This imbalance may be due to loss of helpful bacteria or abundance of certain types of bacteria.
- How does SIBO occur?
Many chemicals, enzymes and immune factors are involved in keeping the bacteria in your small intestine in balance. The normal movement of the intestine and timely emptying of food are also important. Any conditions that affect these processes may cause SIBO.
- How does SIBO affect my body?
Bacteria in the small intestine breaks down food into gas and nutrients. Extra bacteria may lead to extra gas. The extra bacteria may also consume certain vitamins and substances important for your digestion. This can affect your nutrition in the long term.
- What are possible risk factors for SIBO?
- Structural problems:
- Narrowing of intestine after surgery
- Twisting of loops of intestine
- Mass/tumors
- Having pouches in the small intestine called diverticula where bacteria can sit
- Slowed movement of the intestine:
- Medicines like opiods that slow movement of the intestines
- Blockage or reduced movement of the intestines
- Reduced stomach acid:
- Immune conditions reducing stomach acid production
- H. pylori infection
- Gastric surgery
- Conditions affecting absorption
- Altered immunity
- Antibiotic use
- Diseases such as diabetes, thyroid disease
- What are symptoms of SIBO?
The common symptoms can include:
- Pain in your belly
- Belly swelling (bloating)
- A change in your bowel habits like diarrhea (loose stools) or constipation (having difficulty going to the bathroom)
- Extra gas from your intestines
- Fatigue (feeling tired)
- Nausea (feeling like you want to throw up)
- How do you diagnose SIBO?
SIBO is diagnosed when a patient has GI symptoms and evidence of extra bacteria in the small intestine. Some medical experts have agreed on levels of normal and abnormal bacteria.
The most common way to indirectly measure the amount of bacteria in your small intestine is with a hydrogen breath test.
Your provider will advise you to avoid certain medications like antibiotics and laxatives for a few weeks prior to your test. They will also give you instructions on a diet to follow the day before your test.
During this test you will ingest a sugar. This sugar will be broken down by bacteria in your small intestine. The gas byproducts will be given off your body through your breath. The hydrogen level in your breath will be analyzed during a 3-hour period. A hydrogen level above the cut-off suggests excess bacteria.
- How do you treat SIBO?
SIBO can be treated with a short course of antibiotics to help bring the level of bacteria to a healthy balance. However, SIBO can reoccur after treatment and may require repeat treatment.
Your providers may also try to address the underlying factors leading to your SIBO.
Author(s) and Publication Date(s)
Ami J. Panara Shukla, MD, University of Miami, Miami, FL – Published April 2024.