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Small Intestinal Bacterial Overgrowth (SIBO)


Is SIBO causing your IBS symptoms?

Small Intestine Bacterial Overgrowth or SIBO has been estimated to be involved in over half of all cases of IBS (4), with some studies finding it in as many as 70% or more of those with IBS.

What is SIBO?

Small Intestine Bacterial Overgrowth (SIBO) is, as the name implies, a bacterial overgrowth of the small intestine. A healthy small intestine is usually home to very few bacteria, about ten thousand per ml. A person with SIBO has around one million bacteria per ml

In the large intestine, which houses about one hundred billion per ml, bacteria fulfil numerous beneficial functions via their ability to ferment undigested food particles.

With SIBO, because of abnormally large amounts of bacteria in the small intestine, the process of fermentation begins within its narrower confines, producing gases and other by-products in an area which is not adapted to deal with them.

Hydrogen and methane are not produced by human cells but are the metabolic products of fermentation of carbohydrates by intestinal bacteria.

When the production of bacterial gas occurs in the small intestine it may lead to the common IBS symptoms of bloating, cramping, pain, and flatulence. (1) The gases also have an effect on bowel movement with hydrogen having a stronger link to diarrhea and methane having a nearly exclusive link to constipation. (2, 3)

What are the symptoms of SIBO?

The symptoms of SIBO are similar to IBS, and include:

  • bloating, distension
  • flatulence, belching
  • abdominal pain, discomfort, or cramps
  • constipation, diarrhea, or a mixture of the two
  • heartburn, nausea, reflux

What causes SIBO?

Normally bacteria in the small intestine are kept at low levels by:

  • Certain antibacterial secretions in the gut, like gastric acid, pancreatic juices and bile, which keep the small intestine mostly sterile.
  • The migrating motor complex (MMC) which sweeps it clean between meals stopping colonisation of bacteria.
  • The ileocecal valve, which continuously prevents a backflow of bacteria and the translocation of bacterial species from the large intestine.

SIBO develops when these normal mechanisms that control bacterial overgrowth are disrupted. Disturbances in gut immune function and anatomical abnormalities of the GI tract also increase the likelihood of developing SIBO.

Conditions that may predispose you to SIBO

  1. Hypochlorhydria (low stomach acid)
  2. Pancreatic enzyme deficiency
  3. Decreased motility in small intestine
  4. Small intestinal obstructions, adhesions and diverticuli.
  5. An episode of gastroenteritis (food poisoning, travelers diarrhea)
  6. Nerve damage that affects the GI tract
  7. Medications such as opiates and proton pump inhibitors.
  8. Any disease that slows motility (diabetes, scleroderma, hypothyroidism)

How do I find out if I have SIBO?

The most common method to diagnose SIBO is a hydrogen/methane breath test following a 24-hour prep diet and an overnight fast. This test involves drinking a prepared lactulose solution, and measuring the presence of methane and hydrogen gases on the breath. Because bacteria, not humans, produce hydrogen and methane gases, a positive test above baseline would indicate a bacterial overgrowth

Learn more about the test here.

How is it treated?

Just killing the bacterial overgrowth is not enough to resolve SIBO long term because SIBO is prone to relapse if the underlying cause isn’t corrected.

We use a 5 phase protocol, incorporating diet, herbal medicines and nutritional supplements, to ensure SIBO is cleared and won’t return.

  1. Remove foods from your diet that cause inflammation, feed the wrong bacteria and irritate the gut wall, using our specialised eating plan.   
  2. Stimulate production of and/or supplement stomach acid and enzymes.
  3. Herbal antimicrobials to kill the bacterial overgrowth. Physicians at John’s Hopkins and the University of Pittsburgh showed that SIBO treatment using herbal antimicrobial supplements was as effective as rifaximin, the conventional antibiotic most commonly used to treat SIBO. (5) 
  4. Improve small intestine motility with herbal prokinetics and meal spacing.
  5. Enhance gut immunity and restore bacterial balance.

What next?

To learn more about the testing and treatment options available to you we recommend you take a free 15 minute phone consultation with our Naturopath. During this call you can learn more about our treatments and have any questions you may have answered. This call is to determine if we are a good fit for one another rather than a history or complete consultation. There is no obligation, and no strings attached.

It is quick and easy to book your free 15-minute phone consultation using our online calendar. Just click the link below, choose a date and time convenient for you, enter your details, and our Naturopath will call you at your chosen time. Book here




  1. Kunkel D et al. Methane on breath testing is associated with constipation: a systematic review and meta-analysis. Dig Dis Sci. 2011 Jun; 56(6):1612–1618.
  2. Pyleris E, Giamarellos-Bourboulis EJ, Tzivras D, Koussoulas V, Barbatzas C, Pimentel M. The prevalence of overgrowth by aerobic bacteria in the small intestine by small bowel culture: relationship with irritable bowel syndrome. Dig Dis Sci. 2012; 57(5):1321-1329.
  3. Pimentel M, Park S, Mirocha J, Kane SV, Kong Y. The effect of a nonabsorbed oral antibiotic (rifaximin) on the symptoms of the irritable bowel syndrome: a randomized trial. Ann Intern Med. 2006; 145(8):557- 563.
  4. Chaudhary NA, Truelove SC. The irritable colon syndrome. A study of the clinical features, predisposing causes, and prognosis in 130 cases. Q. J. Med. 1962; 31: 307–22.
  5. Chedid V, Dhalla S, Clarke JO, Roland BC, Dunbar KB, Koh J, Justino E, Tomakin E, Mullin GE. Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Glob Adv Health Med. 2014 May;3(3):16-24.
The Digestive Wellness Clinic
12 Junction St Woollahra, NSW 2025 Tel: (02) 8001 6344