Your Guide to Small Intestinal Bacterial Overgrowth (SIBO)

Your Guide to Small Intestinal Bacterial Overgrowth (SIBO)

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A Dietitian’s take on SIBO along with recommendations


What is SIBO? 

Small intestinal bacterial overgrowth (SIBO) is a condition where bacteria that usually inhabit the colon are present in excessive amounts in the small intestine. It is a complex digestive condition that can significantly impact quality of life. It has many overlapping symptoms with irritable bowel syndrome (IBS) and can occur in conjunction with IBS, but it is important to note that they are not the same thing.  

SIBO symptoms include the following: 

  • Abdominal discomfort, including cramping and/or a feeling of fullness 
  • Bloating and/or distension  
  • Gas  
  • Burping 
  • Nausea  
  • Constipation or diarrhea  
  • In severe cases, micronutrient deficiencies such as low B12, low iron, and elevated folate levels 

The symptoms of SIBO arise because the bacteria in the small intestine ferment carbohydrates, resulting in the production of hydrogen gas. Another type of bacteria called archaebacteria consumes hydrogen and produces methane gas. The excess production of hydrogen gas can lead to bloating, abdominal pain, gas, and diarrhea. The excess production of methane can lead to abdominal pain, bloating, and constipation. Note that these symptoms are non-specific, meaning they can also occur with other conditions. If you have these symptoms, it is important to be assessed by a medical professional to determine if it could be SIBO or another digestive issue. 

Can You Test for SIBO?   

The two tests used for SIBO are small intestine aspirates and breath testing. Unfortunately, both tests have limitations. Small intestine aspirate testing involves taking a sample from the small intestine using an endoscope and measuring the number of bacteria in the sample. Although this can determine if bacterial numbers are high, this test is invasive, costly, and the sample taken may not represent the bacterial population present in the small intestine as the bacteria can be “patchy.”

Breath testing is another test that can be used, however there are limitations with it as well. In a breath test, a person consumes a specified amount of glucose or lactose and then hydrogen and methane levels are measured by them blowing into tubes over a specified period of time. This test is very sensitive to any error in the preparation and also false positives and false negatives can occur. Because current testing methods have their limitations, it is important to work with a medical professional to determine if you have SIBO or if it is another digestive condition causing your symptoms.  

Dietary Management and Treatment of SIBO 

Currently, the antibiotic rifaximin is the top choice for SIBO treatment as it is not absorbed into the bloodstream and specifically acts on the gut, killing bacteria there.  If you undergo antibiotic treatment, it is important to address the underlying cause of SIBO as recurrence is common if the root cause is not addressed. There is no specific SIBO diet, but certain diets and dietary factors may help symptoms.

1. Reducing FODMAPs in the Diet

Theoretically reducing FODMAPs (i.e. fermentable carbohydrates) in the diet may help SIBO, however this has not been proven in research. FODMAPs are fermented by bacteria in the gut leading to gas, bloating, and constipation/diarrhea in some individuals. Because of this, reducing intake of these foods may reduce gas production and subsequent symptoms. If this is a diet you are considering exploring, it is strongly recommended to do it under the supervision of a dietitian with experience in gut health and the low FODMAP diet. Learn more about the low FODMAP diet.

2. Elemental diet

This diet consists of taking a formula that has all nutrients broken down into their “predigested” form. The theory with this diet is that nutrients are readily absorbed in the first part of the small intestine and therefore there are fewer food particles for bacteria to ferment at the end of the small intestine. This diet is not recommended as it involves a highly expensive and fully liquid diet, doesn’t taste great, is very restrictive, and is difficult to follow.  


Ginger is what we call a prokinetic, meaning it helps the gut to move! As slow gut transit is a potential root cause for SIBO, ginger may help. Try drinking ginger tea or taking a 100% ginger supplement daily. 

4. Meal Spacing

Spacing out meals every 3-5 hours and giving your gut a break for ~12 hours overnight can help symptoms as it allows the migrating motor complex to work. The migrating motor complex is a cyclical pattern of muscle movement in the gut that pushes food through and is thought to be the “cleaning cycle.” A cycle of the migrating motor complex lasts about 2 hours, however, it is interrupted and stops when food is ingested, so grazing constantly throughout the day is not recommended with SIBO.  

5. Prebiotics or Probiotics

May be supportive, but should be individualized with the support of a dietitian or care provider specialized in digestive health  

A concern with SIBO is that symptoms can result in reduced intake of food due to gut discomfort. This can be problematic for overall nutrition as there is already a potential risk for malabsorption of certain nutrients. Trying to keep the diet as diverse as possible while still managing symptoms is the goal.It is recommended that you reach out to a health care practitioner, such as a dietitian trained in digestive health, to help you with managing SIBO and adjusting diet to support your gut! 

Interested in specialized help for bloating or digestive issues such as SIBO? Our Digestive Health Dietitians can help!

If you are confused about which foods can trigger a cranky gut reaction or what nutrition recommendations can ease your symptoms and improve your gut health, reach out to us for help.

Our incredible and compassionate team of Registered Dietitians provides personalized solutions to your nutrition concerns through our one-on-one nutrition counseling.

Don’t forget to check your health benefits as many plans cover dietitian services!


Keep learning with these blog posts below:

Dietitian Tips on How to Reduce Bloating

Part 1: IBS Series – What are FODMAPs?

Food Sensitivity Tests

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