What is SIBO?

This post will review what SIBO (small intestinal bacterial overgrowth) is, what the symptoms of SIBO are and how to test for it.

What is SIBO?

Have you heard of SIBO? Don't worry if you haven't. Many doctors still aren't familiar with it either. SIBO stands for small intestinal bacterial overgrowth. And it's being increasingly recognized as the cause of many different health problems. Especially gastrointestinal (GI) symptoms and problems.

Why do I care so much about SIBO? Because it affected my life and compromised my health for years before I realized it was the cause of my symptoms. 13 years to be exact. I suffered from chronic diarrhea, abdominal pain and bloating, saw multiple specialists, had numerous tests, spent thousands of dollars on extra testing and no one could give me answers. I eventually gave up on trying to find a cause and was able to manage many of my symptoms by eating a paleo diet (hence why I am so passionate about that diet).

However, when I got a GI infection called C.diff a little over a year ago my poor gastrointestinal (GI) tract just couldn't handle it any more. After being sick with C.diff for almost 4 months, doing 4 rounds of antibiotics and eventually getting a fecal transplant I was finally able to cure my C.diff. Unfortunately my diarrhea and abdominal pain continued on worse than ever. I spent another year with severe symptoms and again had multiple tests that didn't yield any answers. Until I finally got tested for SIBO and found my answer. Now, treating my SIBO was another fun adventure which I won't get into today, but if I can, I want to save you the years of suffering that I went through by sharing more information about SIBO.

Gastrointestinal tract overview

The intestinal tract is made up of many different parts. It starts with the mouth which connects to the esophagus which feeds into the stomach, then moves into the small intestine and finally the large intestine and the rectum.

The small intestine, which connects the stomach to the large intestine is approximately 20 feet long. The small bowel plays an important role in digesting food and absorbing nutrients. It also plays an important role in your body’s immune system. It contains many different lymphoid cells that help fight infections and regulate your immune system.

Your small intestine and large intestine are also filled with bacteria. A lot of bacteria! There are normally less bacteria in the small intestine compared to the large intestine (less than 10,000 bacteria per milliliter of fluid in the small intestine compared to at least 1,000,000,000 bacteria per milliliter of fluid in the large intestine).

Typically the small intestine is mainly filled with what are known as aerobic bacteria, while the large intestine is mainly filled with anaerobic bacteria. These bacteria are important for normal bowel function and are part of a healthy gastrointestinal (GI) tract. These bacteria help your body absorb nutrients, help protect against harmful bacteria and other organisms such as yeast, produce nutrients (including short chain fatty acids, vitamin K and folate) and also help maintain the normal muscular contractions of the small intestine, which help move the contents in the small bowel forward to the large intestine.

What is small intestinal bacterial overgrowth (SIBO)?

SIBO stands for small intestinal bacterial overgrowth. This is a condition where bacteria from the large intestine are present in excess amounts in the small intestine, where they don’t belong. 

Normally, there are few bacteria present in the stomach and the proximal small intestine compared to the large intestine. This is mainly due to the acidity of the stomach and the action of peristalsis (the series of wave-like muscle contractions that moves food through the digestive tract). SIBO is defined as a bacterial population in the small intestine exceeding 10³ organisms/mL in patients with the appropriate symptoms. In other words, it is when too many bacteria are found in the small intestine.

SIBO can also be due to the changes in the type of bacteria found in the small intestine. It often occurs when the small intestine gets overwhelmed with the anaerobic type of bacteria that are typically more prevalent in the large intestine rather than the small intestine. In most cases, SIBO is not caused by a single strain of bacteria, but is usually due to an overgrowth of the many different strains normally found in the large intestine.

What are the symptoms of SIBO?

Since SIBO affects the GI tract, it makes sense that the most common symptoms are GI symptoms. However, SIBO can also lead to many other symptoms. Like Hippocrates said "all health starts in the gut", so it fits that an unhealthy GI tract can lead to problems elsewhere in the body.

The GI symptoms of SIBO can include:

• Diarrhea  
• Bloating and abdominal distension
• Abdominal pain, cramping or discomfort
• Constipation
• Alternating bowel habits (periods of diarrhea alternating with periods of constipation) 
• Gas or burping/ belching
• Vitamin and mineral deficiencies including vitamin B12, thiamine, nicotinamide and iron deficiencies.
• Weight loss
• Fat malabsorption which can also lead to deficiencies in fat soluble vitamins such as vitamins A, D and E.
• Carbohydrate malabsorption

Other symptoms of SIBO include:

• Acne
• Rosacea
• Eczema
• Other skin rashes
• Brain fog
• Memory issues
• Fatigue and weakness
• Mood issues (depression and anxiety)
• Headaches
• Hormone imbalances
• Histamine intolerance
• Joint and muscle or soft tissue pain

As you can see, SIBO doesn't just impact your GI tract. It can impact many other systems in your body. I personally developed acne and keratosis pilaris (another type of skin rash which I've written about previously) related to my SIBO and I have seen other people struggle with many other systemic symptoms related to their SIBO as well.

How do you test for SIBO?

There are a few different tests available to test for SIBO but the most commonly used tests are breath tests. This is because they are easy to do and non-invasive. The gold standard test for SIBO is considered to be a jejunal aspirate (where they take a fluid sample from your small intestine and culture the fluid) but even this test is not very reliable. Plus it's invasive and costly, hence why breath tests are more frequently used, as there are even kits you can get to do the test at home.

There are two different types of breath tests available for SIBO: Either a lactulose or a glucose breath test. Now, there is controversy as to what the best test is as both have their limitations and neither of these tests are completely accurate. Unfortunately none of the tests available for SIBO are perfect. All have their limitations. However, whichever test you and your practitioner choose to do, make sure that it's a 3 hour breath test, and not a one hour test that you choose. Also be sure that they check for both hydrogen and methane gases on the results.

You will want to work with a practitioner familiar with SIBO to help properly interpret your results and get you on an appropriate treatment plan. Treating SIBO can be very challenging and relapses are common so finding someone with an expertise in this area is crucial.

I hope this gives you a better understanding of what SIBO is and how it can impact many different aspects of your health. If you have any questions, please leave them in the comment section, but just note that I cannot provide any medical advice online.

Frequently asked questions:

Other information you will be interested in:

• The causes of SIBO
• What to eat after a colonoscopy
• How to heal keratosis pilaris with diet
• How I healed my keratosis pilaris naturally
• Deodorant health risks

Our expertise:

Dr. Erin Carter, MD, FRCPC, is a physician with board certifications in internal medicine and rheumatology. She is passionate about preventative healthcare including nutrition, environmental health and low toxicity living. She is also a self-trained chef and has been creating and publishing healthy recipes since 2015. Her recipes have been featured on many different websites and online publications.