Hydrogen Sulfide SIBO – When SIBO Tests Are Negative but You Have IBS Symptoms

SIBO (small intestinal bacterial overgrowth) often causes the symptoms of IBS: gas, bloating, abdominal pain, constipation, and/or diarrhea. But what do you do if you have IBS-like symptoms but your SIBO test is negative? You may actually have hydrogen sulfide SIBO, which does not show up on standard SIBO breath tests. Let’s discuss exciting news about diagnosing this condition.

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Hydrogen Sulfide SIBO – When SIBO Tests Are Negative but You Have IBS Symptoms

Dr. Michael Ruscio: Hydrogen sulfide: an overlooked cause of IBS and of SIBO.

Hi, this is Dr. Ruscio, and let’s talk about a very interesting and very impactful study that relates to IBS and SIBO. So what is IBS? And what is SIBO, in case you haven’t heard of either one of these?

IBS is irritable bowel syndrome which includes a constellation of symptoms that typically includes gas, bloating, abdominal pain, and altered bowel function—that may be constipation, it might be diarrhea or loose stools.

And much of IBS, depending on who and what you read, may be caused by underlying SIBO (S-I-B-O), which stands for small intestinal bacterial overgrowth.

And as more people are becoming aware of SIBO and testing for SIBO, there’s a little bit of a quagmire that has formed. Now, SIBO is tested by a breath test. And this breath test typically assesses levels of gas in the breath of hydrogen and of methane.

However, sometimes people will have all of the symptoms of SIBO or IBS, but their breath test is negative. And so it leaves the clinician or the patient scratching their head.

We’ve known about another type of gas called hydrogen sulfide, and this is not able to be tested according to standard SIBO tests. However, a research group just recently developed a breath test for hydrogen sulfide.

And that’s the topic of this study—and I’ll put it up here on the screen—entitled “Hydrogen Sulfide in Exhaled Breath: A Potential Biomarker for Small Intestinal Bacterial Overgrowth.”

So hydrogen sulfide is a different type of gas that can be released by SIBO, or small intestinal bacterial overgrowth, meaning there’s an excess of bacteria in the small intestine.

And here is what the researchers found. Amongst many things, here is what I think is the takeaway, and I’ll quote here: “We found a missing link between breath hydrogen sulfide and SIBO when hydrogen breath tests often fail to diagnose SIBO.”

So essentially what they’re showing is exactly what I said a moment ago. Someone has the symptoms of SIBO or IBS, the typical breath test is negative, and they then found that it was actually hydrogen sulfide that was positive.

So it’s pretty important for those who have either IBS or SIBO and are looking into if they have a bacterial overgrowth as a contributing factor and the standard SIBO breath test has been negative.

Now, what does this mean? Well, what it means is it may still make sense to treat for SIBO if you have IBS symptoms and your SIBO breath test is negative because what you may have is underlying hydrogen sulfide SIBO.

Now, what about doing the hydrogen sulfide test? I don’t believe this test is readily available. We’re currently looking into it. This research group is located in India. I am not sure if their test is something that’s going to be made commercially available or is only locally available or only available for their research purposes at this time.

I’m sure eventually it will be more broadly available, but for right now, it might not be a fruitful endeavor to try to do a hydrogen sulfide test.

There is a hydrogen sulfide test via urine. But its correlation to SIBO and IBS has not been validated, whereas this test has, according to this study, been validated. But accessing this test might be a challenge.

So what you can do or what you can consider, speak with your healthcare provider about, is if you have the symptoms of IBS—gas, bloating, abdominal pain, altered bowel function, loose stools, diarrhea, constipation—and you’ve tested for SIBO and SIBO is negative, you may want to consider a course of treatment for SIBO anyway in case there is actually the hydrogen sulfide SIBO contributing to that.

Now, in terms of treatment options, you may want to start with some of the less invasive treatment options for SIBO, like a low FODMAP diet, which can be helpful, or certain probiotics or herbal anti-microbials that can kill SIBO, or even a liquid elemental diet.

And leave antibiotics as a last resort because we want to try to mitigate any harm if we don’t have a lab test that tells us you definitely need this treatment.

So what I’m suggesting is you treat based upon symptoms. But you have to be a little more careful, a little more conservative with utilization, in my opinion anyway, of antibiotics unless you have laboratory evidence to support the use of antibiotics.

So we can use some of the great tools that we have in natural medicine like low FODMAP, certain probiotics, liquid elemental diets, or herbal anti-microbials.

So if you’re suffering with SIBO or trying to obtain a SIBO diagnosis because you have the symptoms of IBS, hydrogen sulfide might be a key player in that. If you’re working with a good clinician who’s open minded and also willing to go beyond just what lab tests say, you’ll probably be okay. And you’ll probably have this all sorted out.

But in case you’re a little confused and trying to sort out why your lab test and your symptoms don’t match, hydrogen sulfide might be a major contributing factor to that. And that can lead you to, of course, a treatment that you can track to see if it helps you improve your IBS symptoms.

So this is Dr. Ruscio, and I hope this helps you get healthy and get back to your life. Thanks!


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What do you think? I would like to hear your thoughts or experience with this.

Dr. Ruscio is your leading functional and integrative doctor specializing in gut related disorders such as SIBO, leaky gut, Celiac, IBS and in thyroid disorders such as hypothyroid and hyperthyroid. For more information on how to become a patient, please contact our office. Serving the San Francisco bay area and distance patients via phone and Skype.

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