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Symptoms Quiz

Is It IBS?

Take a short quiz to find out if an antibody blood test for IBS is recommended for you.

What is SIBO?

Small intestinal bacterial overgrowth (SIBO) happens when bacteria that is usually found in the large intestine or elsewhere in the body starts to grow in the small intestine, resulting in the improper breakdown of certain foods. SIBO can impact your gut health in many different ways and, in some cases, can lead to malnutrition. While what causes SIBO is an excess of bacteria, there are many conditions that can lead to SIBO like irritable bowel syndrome.

The most common symptoms of SIBO are persistent abdominal pain, cramping, gas, bloating, and diarrhea


Well-established research provides guidance on how to treat SIBO. There are various FDA-approved antibiotics available for treating SIBO and, in many cases, diet manipulation like low-fermentation SIBO diets has been shown to be effective, as well. 

The Clinical Guidelines for SIBO published by the American College of Gastroenterology provide the latest information on the disease, testing, and treatment options. 

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What is IBS?

Irritable bowel syndrome (IBS) is a disease that develops in your large intestine, many times as a result of an organic infection like food poisoning.


Common symptoms of IBS include persistent abdominal pain, cramping, gas, bloating, and changes in stool like chronic diarrhea.


In some cases, IBS can develop into an autoimmunity. This happens because CdtB, the toxin released during the initial infection looks just like a protein important to your gut, called vinculin. The anti-CdtB antibody tricks the body into making antibodies called anti-vinculin, resulting in an autoimmunity that causes damage to the nerves in the gut. 

There are various ways to treat IBS. FDA-approved medications are available, and dietary modifications are commonly suggested. Working directly with your doctor who knows your history is the best way to find the right treatment specifically designed for you.

Foodborne illness affects 15% of the US population each year and is a risk factor for irritable bowel syndrome (IBS). In fact, 1 in 9 (11%) people exposed to food poisoning develop IBS.  Learn more in the Mayo Clinic’s review, Prevalence, Risk Factors, and Outcomes of Irritable Bowel Syndrome After Infectious Enteritis: A Systematic Review and Meta-analysis.

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SIBO and IBS are separate medical conditions, but they commonly coexist, can be connected, and share similar symptoms. That means that if you have been diagnosed with IBS, there is a strong likelihood that you have SIBO, as well.


In fact, approximately 80% of IBS patients also have SIBO. In some cases, SIBO is a result of IBS, but in other cases, it’s not. IBS and SIBO are also distinct based on the type of testing that is required to diagnose each.

Clinicians often use a breath test to diagnose SIBO and an antibody blood test to diagnose IBS. It is common for a patient to take both clinical tests together when diagnosing their GI symptoms.

How Is SIBO Diagnosed?

Bacteria in your intestine consume sugars and produce gases that are released through your breath. With a traditional breath test, patients consume a sugar drink like lactulose and collect samples of their breath over a 90 to 120-minute period of time. This test is called a lactulose breath test. 


The increase of certain gases in your breath over time can indicate SIBO and other illnesses. Traditionally, there were only two gases that were measured: hydrogen which indicates SIBO and methane which indicates intestinal methanogenic overgrowth and is associated with constipation. 


New technology now allows us to measure three gases: hydrogen, methane, and hydrogen sulfide which is associated with diarrhea. To learn more, visit

SIBO Test Results

Looking for more detail about breath testing?  Learn about the established standards for breath testing, including test preparation and results interpretation, in the American Journal of Gastroenterology’s Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus.

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How Is IBS Diagnosed?

Traditionally, IBS was an exclusionary diagnosis, meaning other diseases had to be ruled out in order to diagnose IBS; however, an antibody blood test is an alternative to diagnose IBS more accurately. 


Irritable bowel syndrome can be accurately ruled in with a simple doctor-ordered antibody blood test. This means that antibody markers for IBS, anti-CdtB and anti-vinculin, can be measured with a small blood sample. If either of these antibodies is elevated over the established threshold, you can rule in IBS. 

A positive result on the test also indicates that the root cause of your IBS was an instance of food poisoning (gastroenteritis). If your test result is not positive, your doctor may want to conduct other tests to diagnose your symptoms.

ibs-smart is the only licensed, patented antibody blood test for IBS. Learn more about ibs-smart and antibody testing for IBS here.

A current review in Digestive Diseases and Sciences provides an excellent overview of how gastroenteritis (food poisoning) can lead to IBS and discusses various treatment options for post-infectious IBS. Read Microbiome and Its Role in Irritable Bowel Syndrome.


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The online prescriber service includes:

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Post-Infectious IBS

A significant volume of research shows a clear link between food poisoning and irritable bowel syndrome (IBS).

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Diarrhea & IBS

Chronic diarrhea can indicate disorders, such as inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS).



While irritable bowel syndrome and inflammatory bowel disease share some symptoms, they are completely different illnesses. 

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