Have you heard about SIBO (Small Intestinal Bacterial Overgrowth)? If you are someone with IBS (Irritable Bowel Syndrome), it’s likely that you have. It’s becoming a “buzz word”, with some sources claiming IBS is actually SIBO in up to 60% of cases, we are finding many people are coming to us here at Ignite Nutrition with questions.
We get it! IBS is a functional disorder, meaning although you have obvious symptoms, there is no inherent structural cause and that is frustrating.
SIBO seems like the ‘perfect’ answer, a defined diagnosis and an actual treatment! Unfortunately, it’s not that clear-cut – and it’s leading to a lot of patients wasting time, money, and being bombarded with misinformation. Let’s talk about explaining what SIBO ACTUALLY is (and isn’t!), who is likely to have it, the diagnosis, and the treatment.
What is SIBO?
SIBO is excessive bacterial growth in the small intestine. When tested by a ‘small bowel culture’ (a specific procedure to measure the number of bacteria in the small bowel) a healthy individual’s small bowel contains less than 103 organisms/ml whereas a person with SIBO will have a bacterial population greater than 105 organisms/ml in the small bowel. Additionally, people with SIBO often have a change in the type of organisms present in the small bowel, IE more gram-negative than gram-positive.
In large numbers, the bacteria in the small intestine feed off carbohydrates and as a by-product of their fermentation, produce hydrogen gas. The hydrogen gas may act as fuel for a certain type of bacteria called archaeabacteria which, in turn, produce methane gas. As you may suspect, this excess gas production in a part of the intestine where there should be very little gas production can lead to many of the symptoms associated with SIBO.
What are the symptoms of SIBO?
The most common symptoms of SIBO are:
- Abdominal bloating and distension
- Feeling full quickly when eating
- Diarrhea or constipation
- Fatigue and decreased mental clarity
- Micronutrient abnormalities* (a patient is more likely to have low iron or vitamin B12, high folate)
The symptoms of SIBO are often vague and may overlap with multiple other gastrointestinal disorders. These are of course, symptoms of IBS as well!
In fact, many people present with these symptoms and immediately or errantly get diagnosed with SIBO. While it’s tempting to jump to an organic, tangible diagnosis like SIBO – the reality is, our diagnostic procedures aren’t that spectacular, so it’s extremely important to rule out other diagnoses FIRST and try our best to manage them.
As dietitians, that’s what we’re trained to do! We look at the entire clinical picture, which includes symptoms, dietary patterns, medications, medical history, stress management, etc. before assuming presence of SIBO. And if we feel SIBO is likely, these other factors will help in determining the underlying cause.
It’s also important to understand that bloating and fullness are a normal part of digestion; but when these symptoms cause pain, a decrease in ability to eat, or changes to your quality of life – that’s when we need to pay closer attention. If that’s the case for you, or you’ve had a sudden change to your symptoms, then it is time to seek out a healthcare professional.
Who is at risk of SIBO?
There are some factors that are more likely to be associated with SIBO including:
- Gender – females are more likely to develop SIBO than males
- Age – likelihood of developing SIBO increases with age
- Diarrhea-predominant IBS
- Use of proton pump inhibitors, which decrease gastric acid
- Use of narcotics, which slow GI motility
- Abnormalities in gastric acid or bile
- History of prolonged antibiotic use
- Previous surgeries on the gut, for example, a resection of your intestines
How is SIBO diagnosed?
One way to diagnose SIBO, commonly used in research, is an upper gut aspirate, which is a process of abstracting fluid from the small bowel and culturing the bacteria contained within. This is usually done to measure the numbers of bacteria, but it is often hard to assess the types of bacteria. This is not routinely done due to the cost, the invasive procedure, and the difficulties culturing the small bowel. As well, it only gives us a snapshot of one small area, when in fact, the bacterial overgrowth may be elsewhere in the small bowel.
As a result, hydrogen and methane breath testing is the most common method for testing SIBO. Breath testing consists of a person consuming a defined dosage of carbohydrate (either glucose or lactulose). The gut flora eats up the carbohydrates and produces hydrogen and methane gases as a by-product. Hydrogen and methane are measured, in 15-minute intervals by breathing into tubes. While everyone likely produces some hydrogen, what we’re interested in is the total amount that hydrogen increases over 90 minutes, and whether you produce an excess amount of methane.
There are currently many limitations of using hydrogen and methane breath testing to test for SIBO. These limitations include:
- The sensitivity – or ability to diagnose when SIBO is present, is lower than most commonly used medical tests
- The specificity – or ability to diagnose with SIBO isn’t present, is lower than most commonly used medical tests
- Hydrogen and methane breath testing only assess for 2 kinds of gases, when we know some bacteria produce other kinds of gases, meaning we may miss some diagnoses
- The preparation is VERY specific and if done wrong, may result in an incorrect diagnosis
Since the test for SIBO is not perfect, it is ultimately very important that other diagnoses be managed before moving on to testing for SIBO. This helps to reduce unnecessary costs of testing, and treatment, and reduces unnecessary exposure to antibiotics or antimicrobials.
Your prescribing doctor should be able to properly explain the benefits and limitations of doing this test so that you understand its role in your care.
Interpretation of SIBO Test Results
Interpretation of the results is complex. In fact, we often see patients diagnosed with SIBO that don’t actually have SIBO, because their test has been wrongly interpreted. Interpretation of the test results can vary based on current guidelines, your diagnosis, and the substrate used. Therefore, guidance of a trained healthcare professional is recommended to properly assess your test results for you.
Who should get SIBO testing?
While SIBO testing is available via private labs, we do not recommend everyone go out and purchase a kit. At Ignite Nutrition, we only suggest testing a small subsection of our clients because we don’t want to waste your time or money to do this, we work as a team with your gastroenterologist or family doctor. Many times, an IBS intervention is sufficient, far less expensive, and less risky than jumping right to SIBO testing and treatment. And the fact is, most patients will feel adequately better with simple food and lifestyle intervention!
We consider the full clinical picture, rule out all other causes, and trial dietary and lifestyle management strategies before proceeding with testing to prevent inaccurate results and unnecessary testing and/or treatment.
How is SIBO treated?
The most common, evidence-based method to treat SIBO is with the antibiotic Rifaximin. Rifaximin works locally on the small intestine with limited systemic impacts. Due to Rifaximin’s broad spectrum but localized effect, the risk of antibiotic resistance is minimized. However, Rifaximin does come with a high price tag (especially in the US!). Combination antibiotics or different antibiotics may be suggested based on your breath test results, past medical history, and medical insurance plan – your health care team will come up with an individualized plan for you.
Recurrence of SIBO after antibiotic treatment can be likely if the underlying cause is not addressed – and may require additional medications following antibiotic treatment.
The other option for treatment available is herbal antimicrobials. There is a small body of evidence to support the use of herbals being effective; however, they can also be expensive, and the treatment course may be longer.
A common misconception is that, because they are natural, they must be safer. It is very important to understand that there are risks with herbals as well. Herbal treatments may have poorer adherence to protocol due to their longer treatment time and poor taste of supplements. Also, important to note is that antimicrobial resistance can also occur, and in theory, risk may be greater due to prolonged treatment time with herbals.
What about diet with SIBO?
There is no research to support a specific diet for the treatment of SIBO. In fact, it is very unlikely that diet alone can reduce the number of bacteria in the small bowel. Post-treatment however, theoretically and based on our clinical experience working with patients, a diet low in fermentable carbohydrates (Low FODMAP) can improve and maintain symptoms post-treatment.
Our approach at Ignite is to help our patients with a modified low FODMAP diet that focuses on gut health. We want clients on the least restrictive diet possible to prevent malnutrition and promote enjoyment of food. Unfortunately, many diets online for SIBO tend to be overly and unnecessarily restrictive. We find individualization based on symptoms leads to the least restrictive diet possible, rather than a ‘one-size-fits-all’ approach.
While SIBO might seem like the answer to your IBS, it actually adds additional questions. We can treat SIBO but without understanding the underlying reason WHY it occurred and managing the cause, recurrence can occur. This is why we advocate for working with healthcare professionals trained in gut health who understand the entire clinical picture and can help you find your root-cause.
To work with one of our specialized dietitians on YOUR digestive issues, visit our IBS & Gut Health appointment page here!