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SIBO: An Underdiagnosed Cause of Bloating

SIBO: An Underdiagnosed Cause of Bloating

Belly bloat is frustrating. The outfit that fit fine this morning now feels restrictive or uncomfortable. Sometimes bloat feels like trapped gas or pressure, making us nervously fixate of our bowel habits throughout the day. While occasional bloating is a normal part of digestion, bloating that becomes frequent and interferes with your daily life is a sign that there may be a more significant issue.

If your stomach blows up like a balloon after every meal, it’s time to figure out what’s going on. We consulted Stacie Egan, Gastroenterology Nurse Practitioner to discuss one of the most common culprits of chronic bloat called SIBO.

What is SIBO?

“Small intestinal bacteria overgrowth (SIBO) is a digestive condition that results in the abnormal growth of bacteria in the small intestine,” says Stacie Egan, NP-C. “SIBO is in the same family as IBS, or irritable bowel syndrome, which affects about 11% of the population."

SIBO develops when food sits in the small intestine and slows digestion. SIBO can develop due to underlying causes like physical obstruction, food poisoning, chronic antibiotic use, opioid use, or gastroparesis. While most people are not aware of SIBO, it’s surprisingly common.

How Does SIBO Cause Bloating?

During normal digestion, food mixes with digestive juices in the small intestine and quickly moves down the chain to the large intestine. But when food sits stagnant in the small intestine, it creates a breeding ground for bacteria.

A normal small intestine contains a bacterial population of fewer than 10,000 organisms/mL. Shockingly, this number can multiply to more than 100,000 with SIBO. While bacteria are essential, they can be harmful in excess and in the wrong area.

“The excess bacteria break down carbohydrates and produce methane, hydrogen, and/or hydrogen sulfide. The increased volume of gas stretches the small intestine, causing belly bloat and other symptoms,” says Stacie.

Related: Where You Bloat Tells a Lot About Why

What are the other symptoms of SIBO?

Bloating is the #1 symptom. People affected by SIBO will typically say, “I ate a meal and then looked 6 months pregnant.” Other than bloating, some people experience gas, abdominal pain, diarrhea, and/or constipation. Rosacea, psoriasis, restless leg syndrome, rheumatoid arthritis, and interstitial cystitis are some common co-existing conditions.

How is SIBO diagnosed?

SIBO is diagnosed through a lactulose breath test, The test measures the amount of hydrogen and methane your body produces over a period of time by collecting breath samples. Finding unusual spikes in the levels of both methane and hydrogen indicate the presence of SIBO.

How is SIBO treated?

Antibiotic Therapy

A short treatment of antibiotics can prevent the growth of bacteria in the small intestine and begin relieving the symptoms of SIBO.

Unfortunately, antibiotics don’t just kill the unwanted bacteria in the small intestine. They can also affect the beneficial community of microorganisms in your large intestine known as your gut microbiome. Because of this, treatment for SIBO also includes making dietary changes to ensure lasting benefits.

Dietary Changes with SIBO

A round of antibiotics is not usually enough to keep SIBO at bay long-term. Most patients will need to identify the foods that trigger their SIBO and avoid them. Your Gastroenterology specialist can help you begin that process. By and large, eating a diet rich in plants provides prebiotic fiber and digestive enzymes that will improve the diversity of your gut microbiome. 


If you have chronic bloating that doesn’t subside regardless of what you eat, it’s time to tell your doctor about it, especially if your bloat is accompanied by pain, pressure, and changes in bowel habits (constipation or diarrhea).