Learning you have SIBO (small intestinal bacterial overgrowth), can be both a worry and a relief — the latter because it can help to explain the unpleasant symptoms, such as diarrhea, constipation, bloating, fatigue, and brain fog, you’ve been experiencing.
Another type of SIBO, hydrogen sulfide SIBO, has recently become a popular topic of conversation within the gut health world. But what is hydrogen sulfide SIBO, and does it require a different approach to treatment?
It’s likely that specialized approaches, such as low sulfur diets or avoiding sulfuric medications, are not necessary for this type of SIBO (and may actually distract from helpful treatments).
In this article, we’ll look deeper into what hydrogen sulfide SIBO is, the value of breath testing, why a bigger picture approach to gut healing is important, and how to treat SIBO symptoms in general.
SIBO is short for small intestinal bacterial overgrowth. As the name suggests, this is when abnormal amounts of normal gut bacteria start to grow in the small intestine, a part of the digestive tract where they would not normally be present (most bacteria reside in the bowel, or large intestine).
You may have come across complicated protocols to eradicate SIBO, but it doesn’t need to be the scary diagnosis it’s sometimes made out to be. In fact, SIBO is really just a lab finding that indicates a particular type of dysbiosis or gut microbiome imbalance.
Like all types of gut bacteria imbalances, your SIBO will start to improve when you look at your gut health holistically.
SIBO can generally be categorized as:
These categorizations refer to the main types of gases that the bacterial overgrowth in your small intestine produces. Technically speaking, some say that the methane-predominant version should be referred to as intestinal methanogen overgrowth, not SIBO, as the microorganisms that produce methane, known as methanogens, belong to the classification archaea, not bacteria. However, for our purposes, it certainly still counts as a form of SIBO.
As with any form of gut dysbiosis, digestive symptoms (gas, bloating, belching, reflux, flatulence, abdominal pain, diarrhea, and constipation), are among the most common SIBO symptoms, along with non-digestive symptoms like fatigue, brain fog, and joint pain.
The table below shows the different types of SIBO and the gut symptoms they tend to be most associated with:
|Different Types of SIBO||Most Common Symptom||Predominant Gas on Breath Test|
|Hydrogen Dominant SIBO||General, not specific symptoms ||H2 (Hydrogen)|
|Methane Dominant SIBO or Intestinal Methanogenic Overgrowth (IMO)||Correlated with constipation ||CH4 (Methane)|
|Hydrogen Sulfide SIBO||Correlated with diarrhea [1, 2, 3]||H2S (Hydrogen sulfide, aka rotten egg gas)|
People with irritable bowel syndrome (IBS) and inflammatory bowel disease are much more likely than people without these conditions to be diagnosed with SIBO, according to high quality meta-analyses. For example:
When 50 clinical studies were pooled, more than one-third of IBS patients tested positive for SIBO and IBS patients were nearly five times more likely to test positive for SIBO compared to healthy people .
SIBO has also been associated with the following (though we don’t yet have good research to know whether SIBO treatments can help resolve these conditions):
Until quite recently we only really knew about hydrogen and methane SIBO. However, hydrogen sulfide SIBO is a third type that may be present in some people.
In hydrogen sulfide SIBO the patient, or rather the microbes in the patient’s gastrointestinal tract, produce more hydrogen sulfide gas (colloquially known as rotten egg gas, due to its sulfurous odor), than is normal or healthy.
There is a view held by some individuals and practitioners that more specialized treatments specifically targeting hydrogen sulfide, like low sulfur diets and avoiding sulfuric medications, will help people with this type of SIBO to get better more quickly.
However, neither the available research nor my clinical experience have provided a clear reason to address hydrogen sulfide SIBO or its symptoms any differently than we would methane or hydrogen dominant SIBO cases.
Nevertheless, being able to test for and identify hydrogen sulfide SIBO — which until recently hasn’t been possible — can give answers to patients with uncomfortable symptoms that have so far been impossible to pin down.
Testing for hydrogen and methane SIBO has traditionally been done by breath testing, immediately following the consumption of a measured sugar or carbohydrate solution. Humans don’t usually produce hydrogen or methane gas on the breath, unless they have malabsorption issues, so when these gases are identified, it usually means that bacteria in the gut are producing them .
Unfortunately, hydrogen sulfide is not tested for on traditional SIBO breath tests. That’s why a new test, called the Trio-Smart, is potentially exciting. It is the first that can identify hydrogen sulfide too.
Trio-Smart is also a breath test, but it detects and measures all three of the SIBO gases (hydrogen, methane, and hydrogen sulfide).
My clinical philosophy has increasingly been to take a cautious approach to diagnosing with functional medicine lab testing, because often, expensive tests fail to actually add much to the clinical picture or help make a patient feel better.
While often carried out with the best of intentions by those practising naturopathic or functional medicine, excess or unnecessary tests may just encourage a reductionist approach — i.e., the focus ends up on just one lab marker, and how to improve it, rather than thinking about the patient as a whole and considering the entirety of their symptoms.
When it comes to breath testing specifically, there can also be issues interpreting results if the clinician doesn’t have extensive experience with these tests. Problems that arise can include:
That said, the Trio-Smart test, which has been developed in collaboration with SIBO researcher Dr. Mark Pimental, does have the potential to add value to existing SIBO diagnosis and treatment pathways.
The advantage of the Trio-Smart test is that it provides a more complete picture of what’s going on with your bacterial overgrowth, and may help prevent false negatives as it tests for all three gases. It can be used to monitor what is happening with SIBO before and after a gut-healing diet and probiotic treatment, for example.
If you’ve been diagnosed with hydrogen sulfide SIBO, or indeed any type of SIBO, the most important thing to consider is your diet. This means finding a diet that allows you to have and maintain a healthy environment in your gut.
Sometimes highly restrictive, detoxification-style dietary regimens are recommended straight off for SIBO, but a softer approach with diet is better for most people.
With that in mind, and given the huge overlap between SIBO and IBS, the low FODMAP diet is often an effective (and easier) place to start.
One review of 10 clinical trials found that the low-FODMAP diet led to clinical response in 50–80% of patients with IBS symptoms . This review also found that the low-FODMAP diet resulted in several positive changes in the microbiome, and in overall gut health, including:
An advantage of the low-FODMAP diet is that though it may be somewhat restrictive at first, over time, as your SIBO improves, you should gradually be able to reintroduce and tolerate foods that were previously problematic.
Though people with hydrogen sulfide SIBO are sometimes told to go on a strict low-sulfate, low-sulfur diet, no studies exist to show that this is actually of benefit for this condition.
In general, research on low sulfur diets for gut health is limited. One 2004 study found that high-sulfur foods (which include many common protein foods) was associated with relapses in inflammatory bowel disease .
While it’s always worth experimenting to find the diet that works best for you, avoiding high sulfur foods based only on your lab results (rather than your symptoms or reactions to those foods) might end up distracting you from the bigger picture.
If you have hydrogen sulfide SIBO, it’s best to stick with where the diet research is strongest, which, as per the above, is around a healthy less processed diet that takes into account potential food sensitivities (like low FODMAP).
However, if symptoms persist despite treatment protocols, then consider a low sulfur diet to see if it’s helpful in reducing symptoms.
While it has become a popular opinion that probiotics don’t help SIBO (because they add extra bacteria into the system) this is simply wrong. In fact many studies show taking probiotics can bring benefits for all types of SIBO.
Some of the best success we’ve seen in the clinic with SIBO patients has been when these three types of probiotics were administered at the same time:
Research has shown that multispecies probiotics work better than single species for IBS [27, 28]. To add to this body of research and start to develop a better scientific picture of this treatment approach, we’re currently running a clinical trial using the above triple therapy regimen for those with all three types of SIBO.
The three types of probiotics appear to work together like the legs of a three-legged stool. If the stool only has one or two legs, it’s likely to be unstable. With three legs, the stool is able to stay upright.
Although probiotics get the green light for use by people with SIBO, the same can’t be said for prebiotic foods and supplements (fibers such as inulin and fructooligosaccharides that stimulate bacterial growth).
Though prebiotics can be good for people with robust gut health, they can also be potent producers of hydrogen in the gut‚ which is bad news for many people with SIBO .
Here are some other treatments that you may want to try further down the road if you need more help to feel fully recovered from SIBO. It’s usually best to only introduce these one at a time, a few weeks apart.
Always remember that how your symptoms change is generally more important than changes in lab test results.
SIBO treatment often uses antibiotic therapy with Rifaximin, or a combination of Rifaximin and another antibiotic (often Flagyl or Neomycin), which reduces unwanted gut bacteria in both the small and large intestine .
Herbal antimicrobials such as oil of oregano and berberine may work in the same way as Rifaximin and are commonly used in functional medicine as they may be gentler on the system.
Elemental diets were developed as a medical food for patients with severe digestive issues. They include nutrients broken down into their constituent parts (e.g. amino acids rather than proteins).
Most research into elemental diets has focused on inflammatory bowel disease . However, one intriguing study saw lactulose breath tests normalize in 80% of SIBO patients after two weeks on the elemental diet . Sixty-five percent of patients in the same study saw an improvement in their IBS symptoms.
Elemental diets can be used in flexible ways to manage SIBO symptoms. For example, getting 50% of your calories from elemental meals still reduces gut symptoms and flares .
In other words, if you want to just replace breakfast or lunch with an elemental diet, that can still help your gut.
Bismuth, which is an active ingredient in Pepto Bismol, and also sold in some health supplements, is another option to try for hydrogen sulfide SIBO. It purportedly has anti-sulfur actions, but has more convincing research in the areas of:
Prokinetics are supplement and prescription medications that help improve your gut motility (i.e. they encourage food to move through your digestive tract in a timely manner).
Supporting gut motility with prokinetic supplements or even with prokinetic prescription medication, (such as low dose neomycin, or prucalopride) — may reduce frequency of SIBO relapse. It’s certainly worth discussing this option with your doctor or functional medicine practitioner, to see if prokinetics are right for you.
To recap, hydrogen sulfide SIBO is a type of SIBO that can now be diagnosed with a lab breath test. This can help patients and practitioners better identify the problem, but there’s likely no need for a special set of treatments for this specific SIBO type.
Instead it’s important to work on improving your overall gut health with diet and probiotics, followed by antimicrobials and other therapies if necessary.
For more guidance on healing your gut and improving SIBO symptoms, check out the eight step protocol in Healthy Gut, Healthy You. For more personalized advice, schedule a one-on-one appointment with a practitioner.
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