1. Reliability of SIBO tests
Each medical test has a certain reliability. No test is 100% accurate and reliable. With SIBO testing, precisely with the common hydrogen or methane breath tests, the situation in this context is actually quite bad. The sensitivity of lactulose SIBO breath test is 42% and specificity of 70.6%. What does this mean?
A sensitivity of 42% means that the test correctly identifies only 42% of people with SIBO. This also means that 58% of people with SIBO will have a false negative result - the test will say they don't have SIBO, even if in fact they have. A specificity of 70.6% means that the test correctly identifies 70.6% of people who don't have SIBO. This also means that 29.4% (almost a third!) of people without SIBO will get a false positive result - the test will say they have SIBO, even though they don't.
So, to sum up, the test can lead to many false diagnoses due to its fairly low accuracy - which can lead to an overdiagnosis of SIBO. Then, given that the usual next step is taking a prescription of broad-spectrum antibiotics, with all their risks, it is clear that SIBO diagnosis and treatment requires a careful approach.
One of the problems with SIBO test is that it works with assumption that the ingested solution moves through the digestive system with a certain speed, that is, it reaches an assumed location in the intestines in an assumed time. But the intestinal transit time can vary between people. Some people who are e.g. prone to diarrhea may have shorter transit time. This means that the test solution can reach the colon sooner than in other people, where a lot of gas is then produced and measured during the testing procedure. It may be falsely assumed that this gas production occurred in the small intestine (as it typically does at that timepoint in other people with more typical transit times), when in fact it was a normal fermentation within the colon.
“The test is especially not reliable for diagnosing SIBO when the testing duration exceeds about 60 minutes, that is, for diagnosis SIBO located in the distal small intestine."
“The results of these two audits suggest that a lactulose test alone should not be relied upon to diagnose SIBO, due to the high false positive rate, and should be followed by a glucose hydrogen breath test to confirm the suspected diagnosis if a rise in lactulose is seen within 90 minutes.”
Source: https://gut.bmj.com/content/70/Suppl_1/A178.2
Besides that, these tests are also problematic due to their lack of standardization and possible errors in test preparation, conduction and interpretation. The test protocol needs to be followed strictly in order to get meaningful results.
Does this mean that the SIBO testing is useless? No. But in any case, the results needs to be put into an overall context. And if there is a reasonable suspicion that SIBO is indeed present, it needs to be treated with respect to the further points of this article.
2. What part of the story does the SIBO test result tell?
A positive SIBO test result tells only part of the story. While it indicates an overgrowth of bacteria in the small intestine, it doesn't reveal the full possible complexity of gut dysbiosis. There are many types of dysbiosis, involving various bacterial imbalances and interactions beyond the scope of a SIBO test. The human gut harbors a vast number of different microbes and the test may not say much about many of them. Therefore, a SIBO test result should be considered one piece of the puzzle, not the complete picture, when assessing and treating gut health issues.
Of a particular importance is the fact that there may be other pathogens involved in the dysbiosis, such as candida (or other yeast/mold). In that case, trying to treat SIBO, that is bacteria while not focusing on other culprits, can either lead to lower treatment efficacy, or worse, to actually worsening the overall (gut) health due to clearing up the space for other problem-causing microbes to thrive.
3. Not understanding the severity of the enemy
Underestimating the power of bacteria can be a critical mistake. Bacteria, including those involved in SIBO are often incredibly resilient and prolific. For example, E. Coli bacterium is capable of doubling their numbers in as little as 20 minutes under optimal conditions. This rapid multiplication means gentle approaches often fail because they don't address the sheer volume and the stubborn nature of organisms involved. A comprehensive and long term treatment strategy is usually necessary to achieve meaningful results.
Furthermore, these bacteria can adapt to the treatment (e.g. to the specific antimicrobial being taken). In order to address this, it's important to rotate SIBO treatments, so that bacterial resistance is avoided. The enemy needs to be confused!
4. Killing too much, replenishing not enough
Many typical SIBO treatments involve antibiotics. I don’t only mean the conventional, pharma antibiotics, but also antimicrobials in general, including natural, alternative ones such as oregano oil or berberine. These natural ones can in fact be really potent too. They definitely should not be underestimated just because they are natural!
Anyway, all of these agents may reduce the bacterial overgrowth (that is, if they manage to do that, see the next point), but they can also eliminate so-called beneficial microbes and disturb the overall microbial balance, creating a new, different state of dysbiosis. Although there may be few lucky people for whom it is enough to kill, in general it is the case that replenishing the gut with beneficial bacteria (e.g. probiotics and prebiotics, FMT) is very important after antibiotic treatments to restore a healthy balance. A new environment and gut functioning that can keep the SIBO bacteria in check has to be established. Killing-only approach without sufficient replenishment and other supportive measures can potentially mess up things even more than the original state.
5. FODMAP diet?
Low FODMAP diet is often recommended for managing SIBO symptoms. FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are short-chain carbohydrates that can feed bacteria in the gut.
Can this diet help? Yes.
But the question is – is it really the ultimate solution to SIBO? Does it create a favorable environment in the gut? Does it help to rebuild the microbiome and bring it back to a better condition? In my experience, the answer to these questions may indeed be “no”.
While FODMAD diet is a valid approach and it can bring the so much needed relief in the short term, in general it is not the ultimate answer - rather just a tool to use during the healing journey that needs to be supplemented with other strategies and efforts. The reason why problems with eating high FODMAPs occur in the first place need to be addressed, whether with digestive support, adding a new, better microbiota or overall lifestyle changes. Eventually, if the situation gradually allows it, the aim should be to ditch it and get back to eating diverse, non-restricted diet (but of course, one composed of high quality, fresh foods, while avoiding highly processed foods – that applies regardless of SIBO or anything else). Following a FODMAP diet strictly for a long time can be stressful, overwhelming and create undesirable anxiety, which is naturally the exact opposite of what is beneficial in healing. In addition, it could lead to nutritional deficiencies, especially if followed stereotypically with a little variety of foods. The long term impact of this diet on the microbiome is questionable as well.
6. Lack of focus on biofilms
Bacteria, including those involved in SIBO, often form biofilms - complex bacterial communities encased in a protective matrix. Biofilms are more resistant to antibiotics than free-floating bacteria. This means that the ingested antibiotics may not be effective at all - regardless of their potential antimicrobial strength, they simply may not be able to penetrate the protective matrix and get to the bacteria at all! Thus, treatment strategies need to consider biofilm disruption techniques to enhance the efficacy of SIBO treatment.