SIBO Test: What To Expect, How To Prepare & Next Steps

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Small intestine bacterial overgrowth (SIBO) is a complex disorder of the digestive system that may have many different root causes, making it difficult to diagnose and treat. The primary diagnostic test for SIBO is a non-invasive hydrogen breath test.

SIBO affects millions of people, many of whom are unaware of the disorder. Living with SIBO can decrease your quality of life. SIBO may be triggered by irritable bowel syndrome (IBS), hypothyroidism, or other medical conditions.

While we’ll cover the basics of SIBO, this article is primarily about the SIBO test and how we diagnose SIBO.

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Small Intestine Bacterial Overgrowth

SIBO is an acronym for “small intestine bacterial overgrowth.” A majority of IBS patients also suffer from SIBO. The most prevalent way to test for SIBO is through a breath test.

According to a cross-sectional study from 2003, 6% of healthy individuals could suffer from SIBO without knowing it. That percentage jumps to 15% for adults above 61 years old.

What does SIBO feel like? SIBO feels like you’re bloated all the time. Some individuals with SIBO experience gas, lack of appetite, nausea, constipation or diarrhea, and even joint pain.

How do you know if you have SIBO? You know you have SIBO if testing confirms the condition. However, you may have SIBO if any risk factors (like alcohol use) apply to you or if you exhibit the symptoms listed below.

What are the symptoms of SIBO?

The symptoms of SIBO include:

  • Abdominal pain
  • Bloating
  • Cramping
  • Stomach growling
  • Flatulence
  • Constipation or diarrhea
  • Nausea
  • Fat malabsorption
  • Weight loss
  • Fatigue
  • Rash
  • Joint pain
  • Asthma
  • Skin conditions (acne, eczema, rosacea, etc.)
  • Malnutrition

What happens if SIBO is left untreated? If your SIBO is left untreated, dehydration and malnutrition can occur. In severe cases, dehydration and malnutrition could both lead to death, though this is rare. If you are experiencing symptoms of malnutrition such as pale skin, unusual food cravings, or difficulty breathing, contact your healthcare provider right away.

What causes SIBO?

The causes of SIBO are varied and complex. These medical conditions may cause or contribute to SIBO:

  • Hypothyroidism
  • Cirrhosis of the liver
  • Diabetes
  • Celiac disease
  • Fibromyalgia
  • Parkinson’s disease
  • Scleroderma
  • Small bowel diverticulosis
  • Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)
  • Irritable bowel syndrome

SIBO Risk Factors

These situations increase your risk of developing SIBO:

  • Old age
  • Female gender
  • Alcohol use
  • Previous bowel surgery
  • Certain medications, such as antibiotics or proton pump inhibitors

SIBO Breath Test: What To Expect

How do you get tested for SIBO? You can get tested for SIBO by taking a SIBO breath test — although some healthcare providers administer other tests as well. This procedure tests for levels of hydrogen and methane in your breath, which can indicate bacterial imbalances.

Typically, you begin a breath test by drinking a solution of water and lactulose (sometimes glucose). Bacteria in your small intestine love lactulose and will produce lots of gases when they eat it, while humans are unable to digest it. The test may take 3 hours.

Lactulose is different from lactose. Lactulose is man-made, and the chemical structure is entirely unique. Lactulose acts as a laxative because our bodies cannot digest it. It contains galactose and fructose.

However, many SIBO breath tests do contain lactose. If you have severe lactose intolerance, talk with your doctor about other options.

Although lactulose breath tests have been standard in the past, glucose breath tests are becoming more popular thanks to their accuracy. Lactulose breath tests produce more false positives than glucose tests produce false negatives.

Because SIBO is present in so many cases of IBS, breath testing for SIBO is one way we diagnose IBS.

Let’s talk about what to expect from a breath test.

Before The Test: How To Prepare

Consult with your doctor about how you can best prepare for your breath test. Here’s a general overview of what you can do to prepare.

There are 2- and 3-hour tests. The 3-hour breath test is preferred for most patients, especially if they suffer from constipation. Whatever you and your doctor choose will help you prepare time-wise.

Don’t take probiotics or antibiotics within 4 weeks of your breath test. This can skew breath test results.

Some experts say that it is acceptable to continue taking PPIs (proton-pump inhibitors). However, PrimeHealth recommends talking to your doctor about getting off PPIs, which may increase your risk of SIBO.

Avoid laxatives and fiber supplements the week before your breath test.

24 hours before your test, adhere to a low-residue diet, which minimizes sugars and starches.

12 hours before your test, do not eat. Within the 12 hours before your breath test, drink water and nothing else.

Take all your medications (other than antibiotics, of course) 6 hours or more before your test. Try not to take anything within 6 hours before the breath test.

Within 1-2 hours before your test, do not smoke. 

During Your Breath Test

It’s time for SIBO breath testing to commence. Here’s what happens during the test:

  1. If you’re administering the test at home, make sure the test is not expired. Hopefully, you’re able to carve out time where few distractions will demand your energy.
  2. Some doctors may ask you to rinse your mouth out to reduce contamination from your oral microbiome.
  3. You will provide a baseline breath sample. This may mean blowing up a balloon.
  4. You drink a sugar solution containing carbohydrates (glucose or lactulose), which is meant to react with your gut bacteria.
  5. You breathe into a breathalyzer, or special glass tubes, which measures how quickly your gut is producing hydrogen and methane gas. Some tests require you to continue giving breath samples every 15-20 minutes.
  6. During the test, you will not be able to eat, drink, or sleep. You can’t exercise vigorously. You can ask any questions you think of at any time during the test.
  7. Many doctors’ offices will provide magazines or movies for you to watch while the 2-3 hour test collects gut health data, or you may be able to complete this at home.

Results And Next Steps

Once the provider has collected your breath samples, you can expect test results within 2-14 days, depending on the type of test.

Your doctor can discuss the results with you. If you’re SIBO-positive, you’ll probably discuss treatment options. (We touch on the most popular treatment options below.)

A methane-positive SIBO breath test usually indicates constipation-dominant IBS (IBS-C).

A hydrogen-positive SIBO breath test usually indicates diarrhea-dominant IBS (IBS-D).

Other Types Of SIBO Tests

  • Small intestine culturing — Many believe culturing your small intestine is the gold standard for SIBO diagnosis. However, there are a few flaws with culturing. Mainly, you could culture a section of your small intestine that is unaffected by SIBO, meaning the culture is not representative of your entire small intestine. Another concern: contamination is possible in this test, which is also more invasive and expensive.
  • Symptoms checklist — If your symptom checklist matches SIBO, you may want to save the money and forgo further diagnostic tests. Symptom checklists should be used in conjunction with other diagnostic methods, not by themselves.
  • Personal medical history — Talking about your personal medical history helps your doctor understand what the root cause of your SIBO could be.
  • Family medical history — Discussing your family medical history may reveal genetic dispositions towards certain gastrointestinal disorders, such as SIBO.
  • Physical examination — Endoscopies are invasive physical exams that can help diagnose SIBO. However, the invasiveness and cost mean physical examination like this is not commonly utilized.
  • Blood test — A SIBO blood test can detect SIBO caused by food poisoning. These blood tests typically measure antibodies against toxins and nerve proteins. More often, a blood test would simply rule out conditions other than SIBO.
  • Urine test — You can’t really diagnose SIBO with just a urinary organic acids test. While this test can detect significant bacterial markers in your urine, it’s almost impossible to know the origin of these markers. Urine tests are best used in conjunction with other tests.
  • Stool test — Comprehensive stool testing can help determine the bacterial makeup of your bowels, including your small bowel.

Can I test myself for SIBO? Yes, you can test yourself for SIBO, but at-home test kits are prone to contamination or imperfect implementation. It’s best to receive a breath test in the controlled environment of a doctor’s office to ensure accurate test results are not contaminated.

Treatment For SIBO

How do you treat SIBO? You can treat SIBO in various ways, depending on the root cause of your SIBO, but SIBO treatment boils down to three basic steps (the 3 R’s):

  1. Reduce small intestine bacterial overgrowth
  2. Restore gut motility
  3. Repopulate good bacteria in your large intestine

You can achieve this process of reducing, restoring, and repopulating in several ways.

  • It’s usually wise to avoid antibiotics. If you take too many antibiotics, you may develop antibiotic resistance, which comes with its own issues. You may even develop a secondary, even worse infection, from the antibiotics themselves. On occasion, antibiotics are necessary, but they should be used only as a last resort.
  • Patients should reduce daily stress wherever possible. Constant stress activates immune responses that, in the long-term, harm our bodies. One of many ways that stress can make our immune system turn against us is by triggering SIBO. Cutting out stress may help treat SIBO, and restore normal gut motility
  • It can be beneficial to eat a SIBO diet that can help treat and prevent SIBO. We recommend the low-FODMAP diet, which is also recommended for IBS. (In case you heard this popular myth, do not take honey for SIBO or IBS.)
  • PrimeHealth often recommends dietary supplements as part of SIBO treatment, such as oregano oil or garlic extract (because of the allicin).
  • However, don’t use probiotics until you are sure the small intestine bacterial overgrowth is taken care of. Probiotics help repopulate your large intestine with good bacteria, but they can also worsen small intestine overgrowth — because they don’t make it to the large intestine.

There are medications we may recommend you take to treat SIBO. Typically, PrimeHealth does not prescribe pharmaceuticals unless absolutely necessary. Here are a few medications that may treat SIBO:

  • Prokinetics, like prucalopride or naltrexone
  • Antibiotics, like rifaximin or neomycin
  • Antispasmodics, but mainly for patients experiencing diarrhea more often than constipation

That 2003 study from earlier revealed that SIBO patients typically consume less fiber and less of vitamins B2, B6, and B9 than individuals who did not suffer from SIBO. Consume plenty of fiber (not too much) and enough B vitamins to treat or prevent SIBO.

However, individuals with active SIBO often find that supplemental fiber can exacerbate pain and bloating, so discuss this with your practitioner. 

Outlook For SIBO Patients

Many mainstream gastroenterologists and researchers would call SIBO “incurable,” but what they really mean is that there are multiple treatments that address different people’s root causes.

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  1. Parlesak, A., Klein, B., Schecher, K., Bode, J. C., & Bode, C. (2003). Prevalence of small bowel bacterial overgrowth and its association with nutrition intake in nonhospitalized older adults. Journal of the American Geriatrics Society, 51(6), 768-773.
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