Understanding SIBO and Hydrogen Breath Testing


What is SIBO?


SIBO (or Small Intestinal Bacterial Overgrowth) is a condition where abnormally large numbers of bacteria normally found in the large intestine inhabit the small intestine.

These bacteria are naturally present in the large intestine to help with digestion and to aid in other metabolic processes such as making Vitamin K; however, when they start to overpopulate the small intestine they can cause problems.

But I thought bacteria in the gut are good?

They are…in the right amounts, in the right places, in the right quantities, and the right types.

Bacteria are present naturally in the gut and play an important role in normal bowel health and digestion. They aid in digestion and help prevent infection by destroying harmful bacteria and other microorganisms. They also produce vitamin K. A complex ecosystem of over 500 bacterial species lives in the gut. Some of these bacteria are good; others are not. Most are found in the large intestine.

Just like a fingerprint, we each have a unique makeup to our gut flora determined partly our mother’s gut flora, or the bacteria we were exposed to while in utero, and partly by our own diet and lifestyle. Gut bacteria are different in healthy vs. unhealthy individuals with research tying gut bacteria to the development of many diseases including: diabetes, obesity, fatty liver, heart disease, depression, rheumatoid arthritis, inflammatory bowel disease, IBS, anxiety, autism, and even colon cancer.

People with IBD are believed to have lower levels of certain anti-inflammatory bacteria present in their gut. The exact connection is unclear but it’s thought that some bacteria may cause the immune system to attack the intestines setting the stage for this disease.

Studies show that people with colon cancer might have a different gut microbiota, including higher levels of disease-causing bacteria, than healthy people.

Patients with rheumatoid arthritis may have greater amounts of a bacteria linked to inflammation than people without it.

Why are bacteria a problem then in the small intestine?

The small intestine is responsible for 90% of the digestion and absorption of nutrients and minerals from our food. By the time food gets to the large intestine, the majority of digestion and absorption has already occurred. The large intestine is responsible for absorbing water and electrolytes, forming and storing feces, and transmitting useless waste out of our bodies. It maintains a resident population of over 500 species of bacteria that ferment indigestible materials.

In the small intestine food is still in the process of being broken down and digested. Carbohydrates have yet to be broken down, digested and absorbed, unlike in the large intestines, and bacteria like carbohydrates. They thrive in this high carbohydrate environment, feeding off of undigested carbohydrates. As bacteria consume carbohydrates they produce gas as a byproduct of fermentation. SIBO results, eliciting excess gas, bloating, diarrhea and abdominal distention in affected individuals.

How does SIBO develop?

Under normal circumstances, during periods of fasting throughout the day, undigested food is propelled from the small intestine into the colon via the migrating motor complex (MMC), or our internal intestinal “ housekeeper”. Roughly every two hours, the small intestine initiates this “housekeeper wave” that sweeps through the small intestine and dumps everything including excess bacteria, food, digestive enzymes, bowel secretions and other digestive contents into the large intestine where water can be reabsorbed before fecal material is excreted from the body.

When something impairs this housekeeper wave and the migrating motor complex fails to effectively sweep small intestinal contents clean as a result of food moving through the digestive tract too quickly, motility disorders, diarrhea, or other problems, the small intestine can’t expel the bacteria and bacterial overload (or SIBO) occurs.

Bacteria in the small intestine produce and release hydrogen and other substances into the colon causing gas, bloating, excess water secretion and diarrhea.

What are the symptoms of SIBO?

Symptoms of SIBO are non-specific, but can include:

  1. Abdominal pain or discomfort,
  2. Abdominal distention,
  3. Gas,
  4. Bloating,
  5. Diarrhea,
  6. Dyspepsia,
  7. Constipation (although not typical),
  8. Improper digestion or malabsorption of fats and proteins, and
  9. Weight loss (in severe cases).

What are the risk factors for SIBO?

Risk factors for developing SIBO include:

  1. Structural or anatomic issues (for example, individuals with a history of GI surgeries or gastric bypass surgery may be at increased risk),
  2. Motility disorders (like gastroparesis, dumping syndrome, GERD, chronic constipation, diarrhea, or IBS),
  3. Organ system dysfunction,
  4. Chronic disease,
  5. Elderly age, and
  6. Taking various medications (such as recurrent antibiotics or proton pump inhibitors) that alter the gut microflora.

What conditions are associated with SIBO?

  1. IBS
  2. IBD (Crohn’s disease or Ulcerative Colitis)
  3. Celiac Disease
  4. Diabetes
  5. Fibromyalgia
  6. Rosacea
  7. Parkinson's Disease
  8. Obesity

How can I be tested for SIBO?

Testing by Hydrogen Breath Test is performed to diagnose the condition.
Using a Hydrogen breath test to diagnose SIBO is a simple, non-invasive and inexpensive way to find out if you are affected with the condition. The test takes roughly three hours and is performed in our Flemington office.

What does hydrogen breath testing measure?

The hydrogen breath test measures hydrogen levels in your breath. It is used to diagnose several conditions that cause GI symptoms including SIBO, lactose intolerance, and fructose intolerance.

In humans, only bacteria, specifically, anaerobic bacteria fond in the large intestine (or colon) are able to produce hydrogen. Bacteria produce hydrogen through a process called fermentation when they are exposed to unabsorbed carbohydrates and sugars present in our GI tract.

A small amount of hydrogen is normally produced from unabsorbed food that reaches the colon, however this is minimal. Under healthy conditions, by the time food reaches the large intestine the majority of digestion and absorption has already been completed.

Large amounts of hydrogen may be produced when food is not digested or absorbed properly in the small intestine, and is allowed to reach the large intestine undigested. If carbohydrates are not absorbed properly or too many bacteria are present in the small intestine, a larger amount of hydrogen will reach the large intestine.

Hydrogen that bacteria in the gut produce is absorbed back into the bloodstream through the walls of the small and large intestine. This hydrogen-containing blood travels to our lungs, where it is released and exhaled in our breath. Elevated hydrogen levels tend to be associated with SIBO, IBS, and faster transit times of food through the digestive tract (as is the case in diarrhea or dumping syndrome).

How does hydrogen breath testing work?

Bacteria in the small intestine feed off of undigested carbohydrates from food sources, creating fermentation gases, specifically methane and hydrogen. SIBO breath testing measures these gasses.

To diagnose bacterial overgrowth and rapid transit through the small intestine, lactulose is used. Lactulose is a sugar that is not digested and absorbed by humans. You’ll be asked to drink a container of lactulose 1 hour before your schedule breath test. Then, you’ll come into our office and over the course of 3 hours you’ll be asked to intermittently breath into a machine. Levels of hydrogen present in your breath will be measured.

Lactulose will pass undigested through your small intestine and into your colon. With SIBO, we’ll notice two peaks in the hydrogen levels in your breath: one as the lactulose passes the bacteria in your small intestine and a second after it enters your large intestine.

Are there risks associated with hydrogen breath testing?

There are very few risks associated with breath testing. Patients may feel discomfort from ingesting lactulose. Diarrhea, gas, cramping or bloating may occur. Nausea and vomiting have been reported. Symptoms are usually transient.

How should I prepare for the test?

  1. The breath test should not be performed within 4 week of a colonoscopy or barium enema.
  2. You should not take any antibiotics or bismuth preparations (Pepto Bismol) within 2 weeks or having the breath test.
  3. Avoid laxatives, stool softeners and stool bulking agents for 1 week prior to the test.
  4. The day before the procedure avoid high fiber foods including beans, whole-wheat pasta, fruits, fiber or bran cereals, tofu, nuts, whole wheat and rye breads.
  5. On the day of the test:
    1. a. Do not eat or drink anything for 8 hours before the test.
    2. b. Avoid peppermint oil and all probiotics the day of the test.
    3. c. DO NOT eat, drink (except water), chew gum or tobacco, smoke cigarettes, eat breath mints or candy before or during the test.
    4. d. DO NOT sleep or exercise during the test.
    5. e. DO TAKE prescription medications.
    6. f. DO BRUSH your teeth prior to the test.

How is SIBO treated?

The mainstay of treatment is antibiotic therapy and addressing any underlying contributing conditions.

The information on this website is to provide general guidance. In no way does any of the information provided reflect definitive medical advice and self diagnoses should not be made based on information obtained online. It is important to consult a best in class gastroenterologist regarding ANY and ALL symptoms or signs as it may a sign of a serious illness or condition. A thorough consultation and examination should ALWAYS be performed for an accurate diagnosis and treatment plan. Be sure to call a physician or call our office today and schedule a consultation.

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