 What is the best test for small intestinal bacterial overgrowth? Hi, this is Dr. Ruscio, and if you're not familiar with small intestinal bacterial overgrowth or SIBO for short, this may be responsible for many of the symptoms of IBS, gas, bloating, abdominal pain, altered bowel frequency, meaning constipation or diarrhea. And so this is a condition IBS affects about 10% of the population, so it's a fairly common condition and small intestinal bacterial overgrowth or SIBO may underlie many cases of IBS. Now, this can be tested via a breath test, but there are two different types of breath tests that are typically used. There's a lactilose test and there's a glucose test, and there's controversy as to which one is the best. And so I thought we could talk briefly about the pros and the cons to help you or your doctor determine what the best test might be for you. Now, lactilose is kind of the favored test right now, you could say, in the SIBO community, and there's something to be aware of with lactilose, and I think it's very important. Lactilose produces what's called false positives, meaning the test shows SIBO, but the person doesn't actually have SIBO, so they're positive for the test, but they're falsely positive. It's a false positive test. The reason for this is because lactilose makes its way all the way through the small intestine and then into the large intestine. Now, as that lactilose is traveling through the small intestine, the gas reading that we see is a byproduct of that should be low. But when it gets into the large intestine, the gas level should elevate. However, if for some reason that lactilose makes its way through the small intestine too quickly and gets into the large intestine during the time period when we think it should be in the small intestine, that will give us a false positive elevation of gas. And this has been consistently shown in many of the studies that the lactilose test seems to produce what's called false positives. Now, the merit to the lactilose test is that because it travels all the way through the small intestine, it gives you a good indication of what's happening at the end of the small intestine, where small intestinal bacterial growth may be more common. But we have to counterbalance that with the fact that false positives occur. What this means if you're a patient being treated for SIBO or if you're a doctor treating a patient for SIBO, if someone tests positive with lactilose, you treat them, their symptoms improve, but their labs don't, there's a probability that that person may not be a good person to use lactilose with and you may be seeing a false positive test. And we've actually talked with patients like that in our newsletter in the past. So it's very important to keep that in mind. Now, glucose does not produce the same false positives. So with glucose, if you see a positive, you can rest assured that's a true positive. The negative aspect of glucose is that it does not make it sway all the way to the end of the small intestine in most cases. And if there's SIBO at the end of the small intestine, you may miss it on glucose testing. So both these tests have merit. It's just important that we understand the pros and the cons of each. Lactilose will over-report SIBO or cause false positives. Glucose may under-report SIBO. However, when we look at the studies, the studies seem to favor glucose in my opinion in terms of giving us the most accurate gauge. In any case, either test can be used. It's just important you work with a doctor who's well-trained and knows how to interpret these tests. And more importantly, they will interpret these tests cautiously. There certainly seems to be this this belief on the internet that you can never get over SIBO. And I think a lot of it has to do with the high use of lactilose testing and the people not having the guidance of a good clinician. If someone has symptoms of SIBO, they're treated for SIBO and their symptoms got a lot better, but their labs stay normal. And they're using lactilose. I look at that like false positives where they don't have SIBO, and now we can stop treating you because you feel better. So again, both these tests have merit. If you looked at our website, we recently did a podcast which is fully transcribed where we went through the studies on this issue point-by-point and really picked into the details. But from a big picture perspective, both tests can be used. Lactilose will give false positives, so you have to be aware of that. Glucose seems to be more accurate, but it may miss some cases. One other tip I should mention, or two other tips, and one in reiteration is that if you're using lactilose with someone, you test them for SIBO, they're positive, you treat SIBO, their symptoms get much better or go away, and then you retest them and they still have SIBO via lactilose testing. I would very much look at that like a or be very suspect of a false positive. Also, with lactilose, if you only see positive SIBO at the very end of the test at maybe 100 or 120 minutes, if that's the only positive point you see with lactilose, I would again be more, you know, I'd be suspicious that that might be a false positive, because if the lactilose makes its way through the small intestine quickly in that person, because it's maybe acting as an irritant or a laxative for them, or they have a congenitally shorter small intestine as some do and many Asians actually do, then you may get a false positive. With glucose, if you see positive SIBO, you can rest assured that that's a true positive. However, there is a possibility that that test could be negative, and if the person still has symptoms, you may have missed a SIBO infection at the very end of the attestants, and that person, you may want to treat and then evaluate how they're doing if they respond well, and then you've kind of reaffirmed that SIBO is actually there. Both tests can be used, both tests have may or I personally use both. It's just important to be aware of the pros and the cons. So this is Dr. Rochelle, and I hope this information helps you get healthy and get back to your life. Thanks.