Treating Small Intestinal Bacterial Overgrowth (SIBO)

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Introduction

In the first two articles of this series on Small Intestinal Bacterial Overgrowth (SIBO), I covered what SIBO is, its prevalence, symptoms, and the various diagnostic tests used to identify it. I also discussed why Irritable Bowel Syndrome (IBS) that does not improve with standard dietary changes may actually be SIBO. In this third installment, I outline the main dietary approaches used in treating SIBO alongside antibiotic and evidence-based herbal antimicrobial therapy, and explore whether dietary changes should occur before or after antimicrobial treatment.

Understanding SIBO Treatment Goals

It is vital to remember that SIBO is the presence of bacteria in the small intestine that are not supposed to be there. While dietary changes improve symptoms, they do not eliminate the bacteria themselves. The foreign bacteria must be eradicated, and the underlying cause—such as low stomach acid, pancreatic insufficiency, or motility disorders—must be addressed to prevent recurrence.

Two factors are critical in treatment: (1) recurrence occurs in nearly half of patients within a year if underlying factors like proton-pump inhibitor use or aging are present, and (2) addressing the root cause is the only way to ensure long-term success.

The Role of Fermentable Carbohydrates

Many clinicians prescribe low-FODMAP or Specific Carbohydrate Diets (SCD) to starve the bacteria. However, this has drawbacks. Long-term restriction can reduce beneficial bifidobacteria. Furthermore, research from Dr. Mark Pimentel suggests that bacteria are easier to eradicate when they are active and replicating. If they are starved, they may become dormant and resistant to antimicrobials.

A 2010 study found that combining the antibiotic Rifaximin with partially hydrolyzed guar gum (PHGG) increased the eradication rate from 62% to 85%, while also protecting beneficial gut flora.

Phase I: Symptom Management and Preparation

The first phase involves 4–6 weeks of a low fermentable carbohydrate diet to improve quality of life. During this time, I include PHGG to allow for the minimal bacterial activity needed to ensure that when antimicrobial treatment begins, it is more likely to be successful. PHGG is also well-known for reducing general IBS symptoms in both constipation and diarrhea subtypes.

Phase II: Antimicrobial Eradication

The second phase coincides with a 4-week antimicrobial protocol. The low fermentable carbohydrate diet is maintained, but small amounts of fermentable foods are gradually reintroduced to “feed” the bacteria, making them vulnerable to treatment.

For methane-positive SIBO, combining Rifaximin with Neomycin or Metronidazole has shown higher success rates. Alternatively, herbal antimicrobials have been shown in some studies to be even more effective than Rifaximin, with the added benefits of lower cost and a strong safety record.

Phase III: Liberalization and Maintenance

The final phase is the gradual reintroduction of foods. Once the gut microbiome is restored, most should tolerate a whole-food diet, though avoiding sugar alcohols and certain gums may prevent future issues. If symptoms return, re-testing for SIBO or investigating other causes like histamine intolerance or A1 beta-casein intolerance is recommended.

Final Thoughts

SIBO remains a debated diagnosis, but for many unsuccessfully treated for IBS, this evidence-based combination of diet and antimicrobials offers significant relief. We are still learning about the gut microbiome, including its link to conditions like fibromyalgia. Until we have more definitive answers, using well-studied tools like PHGG and targeted antimicrobials remains the most effective approach we have.

More Info?

If you would like to know more, you can learn about me and the Small Intestinal Bacterial Overgrowth (SIBO) Package that I offer.

To your good health!

Joy

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References

  1. Lauritano EC, Gabrielli M, Scarpellini E, et al. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. American Journal of Gastroenterology. 2008 Oct;103(8):2031-5. [https://www.ncbi.nlm.nih.gov/pubmed/18802998]
  2. Staudacher HM, Lomer MC, Anderson JL, et al. Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. Journal of Nutrition. 2012 Aug;142(8):1510-8. [https://doi.org/10.3945/jn.112.159285]
  3. Furnari M, Parodi A, Gemignani L, et al. Clinical trial: the combination of rifaximin with partially hydrolysed guar gum is more effective than rifaximin alone in eradicating small intestinal bacterial overgrowth. Alimentary Pharmacology & Therapeutics. 2010 Oct;32(8):1000-6. [https://doi.org/10.1111/j.1365-2036.2010.04436.x]
  4. Quartarone G. Role of PHGG as a dietary fiber: a review article. Minerva Gastroenterologica e Dietologica. 2013 Dec;59(4):329-40. [https://www.ncbi.nlm.nih.gov/pubmed/24212352]
  5. Russo L, Andreozzi P, Zito FP, et al. Partially hydrolyzed guar gum in the treatment of irritable bowel syndrome with constipation: effects of gender, age, and body mass index. Saudi Journal of Gastroenterology. 2015 Mar-Apr;21(2):104-10. [https://doi.org/10.4103/1319-3767.153835]
  6. Peralta S, Cottone C, Doveri T, et al. Small intestine bacterial overgrowth and irritable bowel syndrome-related symptoms: experience with Rifaximin. World Journal of Gastroenterology. 2009 Jun 7;15(21):2628-31. [https://doi.org/10.3748/wjg.15.2628]
  7. Low K, Hwang L, Hua J, et al. A combination of rifaximin and neomycin is most effective in treating irritable bowel syndrome patients with methane on lactulose breath test. Journal of Clinical Gastroenterology. 2010 Sep;44(8):547-50. [https://doi.org/10.1097/MCG.0b013e3181c64c90]
  8. Scarlata K. Small Intestinal Bacterial Overgrowth (SIBO). For a Digestive Peace of Mind blog. [https://blog.katescarlata.com/2014/01/22/small-intestinal-bacterial-overgrowth/]
  9. 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 May;3(3):16-24. [https://doi.org/10.7453/gahmj.2014.019]
  10. Minerbi A, Gonzalez E, Brereton NJB, et al. Altered microbiome composition in individuals with fibromyalgia. Pain. 2019 Nov;160(11):2589-2602. [https://doi.org/10.1097/j.pain.0000000000001640]
  11. McGill University Health Centre. Gut bacteria associated with chronic widespread pain for first time. Press Release; June 19, 2019. [https://muhc.ca/news-and-patient-stories/press-releases/gut-bacteria-associated-chronic-widespread-pain-first-time]
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