The Validity of SIBO Tests 

Even if we could accurately diagnose small intestinal bacterial overgrowth (SIBO), if there is no difference in symptoms between those testing positive and those testing negative, what’s the point?

Gastrointestinal symptoms like abdominal pain and bloating account for millions of doctor visits every year. One of the conditions that may be considered for such a “nonspecific presentation” of symptoms is SIBO, a concept that “has gained popularity on the internet in addition to certain clinical and research circles.” SIBO is “broadly defined as excessive bacteria in the small intestine” and typically treated with antibiotics, but “dispensing antibiotics to patients with the nonspecific, common symptoms associated with SIBO is not without risks,” such as the fostering of antibiotic resistance, the emergence of side effects, and the elimination of our good bacteria that could set us up for an invasion of bad bugs like C. diff—all for a condition that may not even be real.

Even alternative medicine journals admit that SIBO is being overdiagnosed, creating “confusion and fear.” SIBO testing “is overused and overly relied upon. Diagnoses are often handed out quickly and without adequate substantiation. Patients can be indoctrinated into thinking SIBO is a chronic condition that can not be cleared and will require lifelong management. This is simply not true for most and is an example of the damage done by overzealousness.” “The ‘monster’ that we now perceive SIBO to be may be no more than a phantom.”

The traditional method for a diagnosis was a small bowel aspiration, an invasive test where a long tube is snaked down the throat to take a sample and count the bugs down there, as you can see at 2:10 in my video Are Small Intestinal Bacterial Overgrowth (SIBO) Tests Valid?.

This method has been almost entirely replaced with breath tests. Normally, a sugar called glucose is almost entirely absorbed in the small intestine, so it never makes it down to the colon. So, the presence of bacterial fermentation of that sugar suggests there are bacteria in the small intestine. Fermentation can be detected because the bacteria produce specific gases that get absorbed in our bloodstream before being exhaled from our lungs, which can then be detected with a breathalyzer-type machine.

Previously, the sugar lactulose was used, but “lactulose breath tests do not reliably detect the overgrowth of bacteria,” so researchers switched to glucose. However, when glucose was finally put to the test, it didn’t work. The bacterial load in the small intestine was similar for those testing positive or negative, so that wasn’t a useful test either. It turns out that glucose can make it down to the colon after all.

Researchers labeled the glucose dose with a tracer and found that nearly half of the positive results from glucose breath tests were false positives because individuals were just fermenting it down in their colon, where our bacteria are supposed to be. So, “patients who are incorrectly labeled with SIBO may be prescribed multiple courses of antibiotics” for a condition they don’t even have.

Why do experts continue to recommend breath testing? Could it be because the “experts” were at a conference supported by a breath testing company, and most had personally received funds from SIBO testing or antibiotic companies?

Even if we could properly diagnose SIBO, does it matter? For those with digestive symptoms, there is a massive range of positivity for SIBO from approximately 4 percent to 84 percent. Researchers “found there to be no difference in overall symptom scores between those testing positive against those testing negative for SIBO…” So, a positive test result could mean anything. Who cares if some people have bacteria growing in their small intestines if it doesn’t correlate with symptoms?

Now, antibiotics can make people with irritable bowel-type symptoms who have been diagnosed with SIBO feel better. Does that prove SIBO was the cause? No, because antibiotics can make just as many people feel better who are negative for SIBO. Currently, the antibiotic rifaximin is most often used for SIBO, but it is “not currently FDA-approved for use in this indication, and its cost can be prohibitive.” (The FDA is the U.S. Food and Drug Administration.) In fact, no drug has been approved for SIBO in the United States or Europe, so even with good insurance, it may cost as much as $50 a day in out-of-pocket expenses, and the course is typically two weeks.

What’s more, while antibiotics may help in the short term, they may make matters worse in the long term. Those “who are given a course of antibiotics are more than three times as likely to report more bowel symptoms 4 months later than controls.” So, what can we do for these kinds of symptoms? That’s exactly what I’m going to turn to next.