SIBO should not be confused with IBS

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SIBO is short for ‘small intestinal bacterial overgrowth’ which simply means that there is too much bacteria in your small intestine. It is a relatively rare condition with disturbed bowel function. Some IBS patients get falsely diagnosed with SIBO and receive treatment that may not work for them. That is why it is important to be able to know the main differences between SIBO and IBS. 

IBS vs. SIBO

Symptoms of IBS and SIBO may overlap since they both affect bowel function. These symptoms include:

  • bloating
  • abdominal pain
  • excess gas
  • diarrhea

However, SIBO also often leads to nutritional deficiencies in patients because of inflammation in the intestinal mucosa, which in turn can affect the intestinal ability to absorb nutrients. Inflammation could contribute to an increased sensitivity to certain foods and possibly also systemic effects such as joint pain. Deficiency is common with fat-soluble vitamins, such as vitamin A, vitamin D, and vitamin E, but also other nutrients including iron.

What causes SIBO?

SIBO is a bowel disorder characterised by an increased presence of bacteria in the small intestine that are normally only found in the large intestine. The bacterial overgrowth is a result of a disturbed function in the small intestine. SIBO is associated with many chronic diseases including irritable bowel syndrome, ulcerative colitis, celiac disease, Crohn’s disease, diabetes, etc. One of the causes of SIBO is motor dysfunction in the small intestine that affects the transit time. As the transit time decreases, it reduces the ability of the intestine to efficiently clear away the bacteria. The motor dysfunction may be due to:

  • nerve or muscle disease
  • systemic diseases, such as rheumatic diseases
  • other diseases related to the digestive tract

Irritable bowel syndrome does not have a clear cause. Most likely many factors work together, both physiological and psychological. It is known that disturbances in the movement patterns of the bowels (intestinal motility), increased pain sensitivity in the digestive tract, and imbalance in the bacterial flora in the large intestine are explanations for the onset of symptoms.

How is SIBO diagnosed?

While irritable bowel syndrome is diagnosed only based on symptoms using the Rome IV criteria, SIBO can be confirmed with a breath test or by obtaining a sample from your small intestine.

Breath test

A carbohydrate breath test is the easiest way to diagnose SIBO. It measures how much hydrogen and methane you exhale since they are the products of bacterial metabolism. It’s non-invasive, cheap, and fast but not always accurate.

Obtaining a small sample from the intestine

This is a more invasive procedure, also known as endoscopy, where the doctor takes a small sample of the fluid in your small intestine using a long tube. Your doctor should determine if this form of diagnosis is truly necessary since it can often be uncomfortable for people.

If you have IBS, you may also have SIBO but it is not always the case.

Treatments for SIBO and IBS

SIBO is not a life-threatening condition and the treatment consists largely of dietary advice. Sometimes, the doctor may prescribe antibiotics but it can lead to the symptoms returning and getting worse since bacteria can become resistant to the antibiotics. Many of the general dietary guidelines found for digestive complaints can also be used successfully for SIBO. The most important thing is to get in touch with a doctor who can make a correct diagnosis. The doctor decides which examinations may be needed to make a diagnosis of SIBO.

Lifestyle and dietary changes are also recommended for the treatment of IBS. IBS is not however treated with antibiotics. There are over-the-counter medicines that can be used to treat IBS symptoms. But getting gradually rid of unhealthy habits should be the first line of treatment for IBS patients. Read more about lifestyle changes you can make to feel better.

References

Takakura, W., & Pimentel, M. (2020). Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome – An Update. Frontiers in Psychiatry11. https://doi.org/10.3389/fpsyt.2020.00664