Small Intestinal Bacterial Overgrowth – SIBO

Posted on April 18, 2019

By Dr. Alexandra Shustina, DO

Bloating, diarrhea, abdominal and discomfort have typically been associated with IBS or Irritable Bowel Syndrome. These are the same symptoms which can be attributed to Small Intestinal Bacterial Overgrowth or SIBO. Did you know that there is a large overlap between Small Intestinal Bacterial Overgrowth and IBS (1)? Many patients diagnosed with IBS have tests which are positive for SIBO. 

What is SIBO anyway? We have a large population of bacteria which live inside and outside of our bodies. They are concentrated in the large intestine. The small intestine has less bacteria and a different population. When the numbers of bacteria increase in the small intestine, SIBO occurs. This overgrowth can cause a variety of symptoms. Some people have no symptoms and feel great while others are malnourished with severe diarrhea and major discomfort. Some people can even be constipated with SIBO. What predisposes someone to this disorder? We have seen that low stomach acid can make someone more likely to have SIBO. Acid in the stomach kills bacteria. Decreased acid can allow bacteria to stay alive in the stomach and to pass to the small intestine to overgrow. People on acid blocking medications have decreased stomach acid and have higher rates of SIBO (2). Antibiotics alter the gut bacterial populations and can allow for bugs to grow out in the wrong places. Any type of immune deficiency or chronic medical illness can predispose someone to SIBO 

The small intestine is a long and coiled tube with muscular walls. The muscles in the walls of the small intestine contract sequentially to propel the food forward. This sequential motion of the intestinal wall is a vital part of the digestive process and is called peristalsis. Peristalsis is a type of motility or inherent motion of the digestive tract. When motility is normal, it is difficult for bacteria to overgrow since the contents of the intestine are constantly being pushed forward. The problem occurs when motility is disturbed and food and bacteria are able to sit in one spot for too long. This stasis allows the bacteria to grow out to abnormal levels.

SIBO is typically diagnosed through a breath test. This a non-invasive test when a person drinks a sugar solution and the breath is tested for hydrogen and methane gas at different time intervals. SIBO can be treated with antibiotics or with anti-microbial herbal therapy. Herbal therapy has been shown to be at least as effective in treating SIBO as antibiotics (3). Most importantly the underlying cause of the SIBO needs to be addressed in order to prevent the SIBO from returning. Many patients with SIBO have underlying motility dysfunction. Visceral manipulation is an effective tool to treat gut motility. Dietary recommendations for patients with SIBO needs to be customized to the individual patient. Many patients do well with a low FODMAP diet (5). FODMAPS are short chain carbohydrates which some people do not digest properly. This is seen frequently in IBS and SIBO. In our practice, the combination of herbal therapy with visceral manipulation and dietary and lifestyle changes has been effective in eradicating SIBO.


  1. Carrara M, Desideri S, Azzurro M, Bulighin GM, Di Piramo D, Lomonaco L, Adamo S. Small intestine bacterial overgrowth in patients with irritable bowel syndrome. Eur Rev Med Pharmacol Sci. 2008;12:197–202.
  2. Lombardo L, Foti M, Ruggia O, Chiechcchio A. Increased Incidence of Small Intestinal Bacterial Overgrowth During Proton Pump Inhibitor TherapyClinical Gastroenterology and Hepatology , Volume 8 , Issue 6 , 504 – 508.
  3. Chedid V, Dhalla S, Clarke JO, et al. Herbal Therapy Is Equivalent to Rifaximin for the Treatment of Small Intestinal Bacterial Overgrowth. Global Advances in Health and Medicine. 2014;3(3):16-24. doi:10.7453/gahmj.2014.019.
  4. Müller A, Franke H, Resch K, Fryer G. Effectiveness of Osteopathic Manipulative Therapy for Managing Symptoms of Irritable Bowel Syndrome: A Systematic Review. J Am Osteopath Assoc 2014;114(6):470–479.
  5. Roest, R. H., Dobbs, B. R., Chapman, B. A., Batman, B. , O’Brien, L. A., Leeper, J. A., Hebblethwaite, C. R. and Gearry, R. B. (2013), The low FODMAP diet improves gastrointestinal symptoms in patients with irritable bowel syndrome: a prospective study. Int J Clin Pract, 67: 895-903.

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