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Did You Know There is More Than One Type of SIBO Test on the Market?

Welcome to the Gut Honest Truth blog where a Certified Functional Medicine Practitioner gives you digestible information to tackle your chronic health concerns.

That’s me, Katie Morra;

Side note- If you want an even deeper dive into understanding and resolving Small Intestinal Bacterial Overgrowth - check out my "How to Get Rid of Your SIBO" e-book. This book aims to help you reduce symptoms of bloating, excessive gas, constipation, diarrhea and other symptoms of bacterial overgrowth in the gut by getting to the root cause and supporting a healthy gut microbiome and motility.

And as always, working one-on-one for your specific needs is always our top recommendation, check out our appointment options to get started with one of our licensed health care professionals today.

On to the post...

Small Intestinal Bacterial Overgrowth aka SIBO aka Queen of IBS

SIBO means that there is bacteria overgrowing in a place where it shouldn’t be, the small intestine. I like to refer to SIBO as a party on the rooftop when it should be in the basement. This diagnosis is responsible for up to 80% of all IBS cases.

Essentially the small intestine should be fairly low bacterial counts. The large intestine, on the other hand, should have trillions of bacteria growing in it and is often what people are referring to when you hear the term “microbiome”. I suspect there will be a lot more research about the bacterial flora in the small intestine in the near future but as of 2023 it is generally agreed that the small intestine is meant to be a sterile, low bacteria place.

So, you might be asking what the point of your small intestine is if it should be kept so neat and tidy?

The small intestine is a muscular, open tube, that extends from your stomach to your large intestine (colon). It is made up of three sections: duodenum, jejunum, and ileum. The small intestine’s primary purpose is to digest your food so that you can absorb the energy and nutrients that you need to lead a healthy and happy life. The small intestine also produces hormones that stimulate the release of bile and pancreatic fluids. The small intestine is also where peristalsis primarily occurs, or the contractual movement of food, bacteria, and debris through your digestive tract.

Issues with this organ, like an overgrowth of bacteria, greatly impairs someone’s ability to digest and absorb food over time. This can lead to an abundance of nutrient deficiencies which will have an effect downstream on everything.

The 3 Types of SIBO You Could be Diagnosed With:

Pro tip: this information is important for both patients and practitioners.

A person can be diagnosed with three types of SIBO: hydrogen (H2), methane (CH4) and hydrogen sulfide (HS). They are named after the gas that the bacteria associated with each type of SIBO produce in the body. Before you start to think you’ve stepped back in time to high school Chemistry class and start sharpening your No. 2 pencil, let me quickly break down each subtype.

Hydrogen SIBO:

Hydrogen is caused by an overgrowth of bacteria - such as klebsiella, e. coli, proteus, or aeromonas - and is known for causing "IBS-Diarrhea". One important fact about hydrogen gas is that it can be a food source for the other types of SIBO (to be defined later). What does this mean for you? If you were diagnosed with combination SIBO (methane and hydrogen), not only will you need to remove the methane but you will also need to target the hydrogen producing bacteria. Otherwise you will likely have a hard time clearing the bacterial overgrowth.

Methane SIBO:

Methane is actually produced by an archaea and not a bacteria but for the purposes of this book we will consider them one and the same. Methane SIBO tends to be what causes “IBS-Constipation”. A not-so-fun fact about methane producers is that they are amazing at extracting the calories out of food. Thus, people who suffer with methane overgrowth often experience weight gain or inability to lose weight despite a clean dietary lifestyle. On top of this, it is often more challenging to treat than hydrogen dominant SIBO alone.

Hydrogen Sulfide:

Hydrogen sulfide's trademark is sulfurous gas that smells like rotten eggs. Patients with this form of SIBO often report loose stool but may also experience brain fog, memory issues, fatigue, muscle pain, diarrhea and constipation. With this type, hydrogen sulfide-producing bacteria and methane producers compete for hydrogen gas... a miserable bacteria battle royale. Often when our sulfur metabolism isn’t working correctly and our body recognizes that we are low in sulfate, it will self-correct by growing more hydrogen sulfide-producing bacteria leading to this variety of SIBO.

The 3 types of SIBO tests currently on the market:

Note: Each test involves drinking a solution made of either glucose or lactulose then after 2 or 3 hours of breathing into collection tubes to capture the gas produced by the bacteria in your intestinal tract. I prefer the 3 hour test over than 2 hour test and recommend you start there. If you have had a SIBO test run before, go grab your lab and check what type of substrate was used because there may be a chance you used the wrong substrate for your symptoms.

Glucose test:

Glucose testing detects SIBO only higher up in the small intestine aka proximal and near the stomach, as the solution you consume is absorbed by the small intestine. If the bacteria is farther down the small intestine aka distal and near the large intestine, the odds of a false negative (not actually negative) increase. There is a much lesser chance that you will detect SIBO with this test since most cases of SIBO are happening more distally, but if detected the likelihood that it is a true positive (actually positive) is higher. Some believe this is not a great test for individuals suffering from constipation. If you are struggling with IBS symptoms within an hour-ish of eating, this test may be for you. If your symptoms are a few hours after eating meals, opt in for the lactulose test.

Lactulose test:

Lactulose testing has a higher probability of finding SIBO as the solution is not absorbed by the small intestine. Because it is not absorbed the lactulose sometimes enters the large intestine (home of those aforementioned trillions of precious bacteria) which can generate a lot of false positives (not actually positive). This is where your practitioner needs to use their deduction skills of the larger clinical picture, take all tests with a grain of salt and make an educated and informed decision on your diagnosis aka if it walks like a duck, quacks like a duck. That said, the rate of false negatives is lower with this type of test which is why it is the most commonly prescribed test.

This test was released in 2020 and can only be ordered by a physician. It is the first time we are able to test hydrogen sulfide (as well methane and hydrogen) SIBO. They have both glucose and lactulose options for their testing (revisit the above paragraphs). Since testing for hydrogen sulfide was not possible previously, research on treatment is still limited. However, the Trio Smart test might be a game changer in the diagnosis and treatment of SIBO as a whole.

False negative, false positives, new entrants, missing subtypes - obviously there is no perfect option for SIBO testing today. Frustrating? Yes. Still worth it? Absolutely! Each type and severity of SIBO requires a specific treatment (to be covered later). Knowing the type - or types - of SIBO and where the bacteria is growing in the GI tract is critical in knowing how to treat. Test, test, test!

Ready for some testing tips?

1. I recommend the SIBO tests that are mailed directly to you so you can test from the comfort of your home. Some physicians offer in-office tests, but often in-office tests are the shorter, less accurate tests. Plus who wants to spend 3 hours in a Dr.’s office?

2. I always recommend the 3-hour over the 2-hour breath test that is also offered.

3. You can’t test SIBO with a stool test. I repeat, if your practitioner diagnosed you with SIBO through a stool test, it might be time to find a new practitioner.

4. Stop taking all herbal, botanical, antimicrobial, and probiotics for 2 to 4 weeks prior to testing (depending on your patience). It is recommended to wait 4 weeks after antibiotics.

5. Avoid vitamin C, magnesium, ginger and any other supplements or medications that may act as a laxative at least 4 days prior to testing.

6. For 24 hours prior to testing you will avoid fiber, lactose, spices and have a diet focused on clear broths, lean meats and white rice.

7. Comply to a 12 hour fast the night before testing. This means if you stop eating at 8 pm, you will complete the test at 8 am at the earliest with no eating prior.

8. Avoid exercising prior to testing.

9. Avoid smoking prior to testing.

10. Make sure you drink the solution that comes in the box, I can’t stress this enough! You would be surprised how many people forget this part.

If you are looking for someone to help properly test you and guide you on your SIBO journey, we recommend working with a health practitioner at Gut Honest Truth. If you are a practitioner and wanting to learn more about functional testing ordering and interpreation and how to best support your patients, come join us at GHT Academy.

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