SIBO: Condition Overview

How a SIBO Nutritionist Can Help

SIBO: Overview, Symptoms, Treatments & How Diet Can Help

As a SIBO nutritionist who has had SIBO, I’d like to formally welcome you to our comprehensive overview.  

We know SIBO can be confusing and there is a lot of misinformation on this condition.  We want to help you understand SIBO so you can advocate for your health.   And don’t lose hope!  It’s important to know that diet and improving digestive function can help improve symptoms and help resolve it for good.

Ready for a deep dive on SIBO?  Let’s go! 

SIBO is a relatively new condition identified by the medical community. Being diagnosed with SIBO can be a confusing and frustrating situation because:

  • Not every doctor is aware of it or understands how to treat it
  • It’s hard to diagnose
  • There are numerous root causes
  • There are multiple ways to treat it
  • There are a plethora of diets and supplements claiming to help

What is Small Intestine Bacterial Overgrowth (SIBO)?

There is no consensus on the specific definition but it is generally accepted that SIBO is a condition in which bacteria normally found in the colon overgrows in the small intestine and causes abnormal digestive symptoms. Essentially, it’s too many good bacteria in a place it doesn’t belong.

It’s important to note that despite the term “bacterial overgrowth”, SIBO is not an infection. 

What Are the Symptoms of SIBO?

The following symptoms are most commonly associated with SIBO:

  • Diarrhea
  • Abdominal pain
  • Gas & bloating
  • Constipation
  • Nutrient deficiencies, anemia & weight loss

Because these are not symptoms specific to SIBO, it is hard to diagnose and must be differentiated from a functional gut disorder or another condition.

Why Are You Still Stuck With SIBO?

What Causes SIBO?

There is no one single known cause. It can occur when there is breakdown in one or more of your body’s innate mechanisms designed to keep bacteria from colonizing in the small intestine such as:

  • Anatomical Abnormalities – resulting from abdominal surgery such as adhesions or diverticula.
  • Low Stomach Acid – Gastric acid in the stomach kills many bacteria before exiting the stomach. Low stomach acid levels can raise gastric pH leading to an overgrowth of bacteria. What can cause low stomach acid?
    • Medications such as narcotic pain medications and proton pump inhibitors taken for conditions such as acid reflux, heartburn, GERD, LPR, ulcers, gastritis and for H. pylori.
    • Aging – As we grow older, we can produce lower levels of stomach acid.
  • Bile & Enzyme Deficiencies – They limit growth of bacteria in the small intestine. What can cause these deficiencies?
    • Bile deficiency can be caused by dysfunction of the gallbladder and/or liver.
    • Digestive enzymes need stomach acid to activate, so once again, we see the need for stomach acid. Also, damage to the small intestine caused by inflammation from food sensitivities, medications, toxins and chronic stress (via stress hormones) can cause lower production of digestive enzymes. The overgrowth of bacteria that leads to SIBO can also cause digestive enzyme deficiency resulting in a never-ending cycle of poor digestive function.
  • Poor Motility – Not to be confused with constipation, poor motility refers to the slow function of the migrating motor complex (MMC). These are the muscles in the digestive tract that move food, bacteria and toxins down and out. The MMC is crucial to maintaining balanced gut bacteria populations. What can cause poor motility?
    • Conditions such as Parkinson’s, diabetes, pancreatitis and hypothyroidism
    • Narcotic pain medications
    • Low stomach acid related to aging
  • Ileocecal Valve Malfunction – This is the valve between the small intestine and the colon. It prevents retrograde movement of bacteria from the colon to the small intestine.

It’s important to note that SIBO is a result of one of the above conditions. The root cause must be resolved or there is a high chance for reoccurrence.

SIBO & Other Conditions

SIBO occurs at a relatively high rate with the following conditions:

  • Abdominal surgery
  • Celiac disease
  • Chronic fatigue syndrome
  • Chronic pancreatitis
  • Crohn’s disease
  • Endometriosis
  • Fibromyalgia
  • Irritable Bowel Syndrome (IBS)
  • Low thyroid function (hypothyroid or Hashimoto’s thyroiditis)
  • Muscular dystrophy
  • Ulcerative colitis

How Does SIBO Cause Symptoms & Intestinal Damage?

  • The bacteria that colonize in the small intestine ferment carbohydrates resulting in gas.
  • This overgrowth of bacteria compromises enzyme function by injuring the intestinal lining, affecting digestion and nutrient absorption.
  • Damaged intestinal lining can lead to increased intestinal permeability, otherwise known as “leaky gut”.
  • Bacteria consume your nutrients such as vitamin B12 and protein, which can lead to nutrient deficiencies.
  • Bacteria may deconjugate bile acids, which can lead to fat malabsorption and deficiencies of fat-soluble vitamins.
  • Bacteria can produce various endotoxins such as ammonia and d-lactate that may have negative effects across the whole body such as fatigue, brain fog and joint pain.

How is SIBO Diagnosed?

There is no gold standard and all methods have limitations. There are often false negative/positive results.  Three methods are used (more than one can be used for a more confident diagnosis):

  1. Endoscopy with culture of the small intestine bacteria. This option is invasive & expensive.
  2. A lactulose or glucose breath test, which measures hydrogen, methane and hydrogen sulfide. These gasses are not produced by humans and their presence signify the metabolic byproducts of carbohydrate fermentation by bacteria. These tests are relatively inexpensive, not invasive and often performed at home.
  3. Trial of antibiotics to determine if symptoms improve.

How is SIBO Treated?

There are three main principles in treating SIBO:

1. Treat the underlying cause

SIBO can be a relapsing condition because it’s a secondary condition. The best results involve treating the root causes, if possible.

2. Eradicate the overgrowth of bacteria

Doctors may prescribe antibiotics and/or herbal antimicrobials for SIBO along with other supplements such as fiber or probiotics. There are numerous protocols a doctor may employ based on the outcome of the breath test, medical studies or clinical results in their own client population. Multiple rounds of treatment may be necessary.

Rifaximin is the most studied antibiotic for SIBO and may be the preferred option because it stays local to the small intestine and doesn’t disrupt the good bacteria in the colon.

The Elemental Diet is a physician-monitored liquid diet. It has been shown to normalize breath tests. This may be an appropriate approach for those allergic to antibiotics or for those who don’t respond to them for treatment.  With that being said, it is an extreme approach that we don’t recommend because it can cause diarrhea, weight loss and candida.  

3. Address nutrient deficiencies with a SIBO nutritionist

Nutritional support is required in those with nutrient deficiencies, malnutrition and weight loss.

What is the Best Diet for SIBO According to a SIBO Nutritionist?

Keep in mind that diet does not cure SIBO but rather helps manage symptoms and create a hospitable environment for healing. What CAN a SIBO diet do to help?

  • The right diet can help improve digestive function, which allows you to tolerate even more food with fewer symptoms
  • It can be customized to help improve bloating, gas, abdominal pain, diarrhea and/or constipation
  • Improve motility of the small intestine
  • Replete nutrients that are required for healing
  • Improve the gut microbiome, which can improve digestive function

There are a variety of diets that reduce fermentable carbohydrates to varying degrees such as the Low-FODMAP Diet, the SIBO-Bi-Phasic Diet and Paleo Diet.  We work with our clients to select a diet and modify it based on severity of symptoms, underlying cause, and presence of other health conditions.

It’s important to note that these diets are not forever diets. They are tools used to help manage symptoms, identify food sensitivities/intolerances and to help the digestive system heal. Once symptoms have improved, we can carefully and systematically reintroduce previously restricted foods. The goal is to liberalize the diet as much as possible while limiting symptoms.

Keep in mind that SIBO diets are meant to be short term elimination diets to help manage symptoms and heal the gut.  Often the more restrictive diets do more harm than good.

How to Prevent SIBO From Relapsing

SIBO is a relapsing condition, especially if the underlying causes are not identified and corrected. Options include:

  • Watchful observation and retreatment if necessary
  • Promotility drugs (also known as prokinetics) to address the poorly functioning migrating motor complex (MMC). Prescription motility drugs used for SIBO prevention include erythromycin, cisparide and prucalopride. Herbal prokinetics include Iberogast, ginger and Motilpro.
  • Lower carbohydrate diet
  • Use of select probiotics/prebiotics. A study indicates that probiotics may be protective for prevention of SIBO in those at high risk.

Our Functional Nutrition Approach to Healing SIBO

SIBO is a challenging condition that often relapses. Gut-healing protocols and addressing the root cause are essential to long lasting relief.  Through our 1:1 nutrition counseling program, we work with clients to:

  • Elicit a detailed health history to determine the potential root cause(s) and concurrent health conditions
  • Understand symptoms and triggers
  • Test for SIBO using at-home breath tests
  • Recommend a personalized SIBO diet to implement during antibiotic treatment
  • Improve digestive function
  • Implement a gut-healing protocol after treatment based on symptoms, health history, concurrent conditions and preferences
  • Address nutrient deficiencies, if necessary
  • Advise on lifestyle changes and stress reduction techniques
  • Reintroduce foods slowly and systematically to determine food sensitivities and intolerances
  • Celebrate the victories every step of the way!


We also offer our Solving SIBO Program that helps you customize your own gut healing protocol at a lower cost. 

View References

Bures, J., Cyrany, J., Kohoutova, D., Förstl, M., Rejchrt, S., Kvetina, J., … Kopacova, M. (2010). Small intestinal bacterial overgrowth syndrome. World Journal of Gastroenterology : WJG, 16(24), 2978–2990.

Chedid, V., Dhalla, S., Clarke, J. O., Roland, B. C., Dunbar, K. B., Koh, J., … Mullin, G. E. (2014). Herbal Therapy Is Equivalent to Rifaximin for the Treatment of Small Intestinal Bacterial Overgrowth. Global Advances in Health and Medicine, 3(3), 16–24.

Gatta, L., Scarpignato, C., McCallum, R. W., Lombardo, L., Pimentel, M., D’Incà, R., … Cerda, E. (2017). Systematic review with meta‐analysis: rifaximin is effective and safe for the treatment of small intestine bacterial overgrowth. Alimentary Pharmacology & Therapeutics, 45(5), 604–616.

Ghoshal, U. C., & Srivastava, D. (2014). Irritable bowel syndrome and small intestinal bacterial overgrowth: Meaningful association or unnecessary hype. World Journal of Gastroenterology : WJG, 20(10), 2482–2491.

Gorard, D. (1998). Is the cyclic nature of migrating motor complex dependent on the sleep cycle? Retrieved from

Grace, E., Shaw, C., Whelan, K., & Andreyev, H. J. N. (2013). Review article: small intestinal bacterial overgrowth – prevalence, clinical features, current and developing diagnostic tests, and treatment. Alimentary Pharmacology & Therapeutics, 38(7), 674–688.

Khalighi, A. R., Khalighi, M. R., Behdani, R., Jamali, J., Khosravi, A., Kouhestani, S., … Khalighi, N. (2014). Evaluating the efficacy of probiotic on treatment in patients with small intestinal bacterial overgrowth (SIBO) – A pilot study. Indian Journal of Med Res, 140(5), 604–608.

Kraijicek, E., & Hansel, S. (2016). Small intestinal bacterial overgrowth: A primary care review. Mayo Clinic Proceedings, 91(12), 1828–1833.

Leventogiannis, K., Gkolfakis, P., Spithakis, G., Tsatali, A., Pistiki, A., Sioulas, A., … Triantafyllou, K. (2018). Effect of a Preparation of Four Probiotics on Symptoms of Patients with Irritable Bowel Syndrome: Association with Intestinal Bacterial Overgrowth. Probiotics and Antimicrobial Proteins, 1–8.

Rezaie, A., Pimental, M., & Rao, S. (2016). How to test and treat small intestinal bacterial overgrowth: an Evidence-based approach. Current Gastroenterology Reports, 18(8), 1–11.

Soifer, L. O., Peralta, D., Dima, G., & Besasso, H. (2010). Comparative clinical efficacy of a probiotic vs. an antibiotic in the treatment of patients with intestinal bacterial overgrowth and chronic abdominal functional distension: a pilot study. Acta Gastroenterologica Latinoamericana, 40(4), 323–327.

Takahashi, T. (2012). Mechanism of Interdigestive Migrating Motor Complex. Journal of Neurogastroenterology and Motility, 18(3), 246–257.

Zhong, C., Qu, C., Wang, B., Liang, S., & Zeng, B. (2017). Probiotics for Preventing and Treating Small Intestinal Bacterial Overgrowth: A Meta-Analysis and Systematic Review of Current Evidence. Journal of Clinical Gastroenterology, 51(4), 300–311.

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Sara Kahn, MS, CNS, CDN

Sara Kahn, MS, CNS, CDN

SIBO Nutritionist

Sara Kahn is a board-certified nutritionist specializing in digestive health conditions like SIBO, IBS, acid reflux and more.  She’s the founder of Belly Bliss Nutrition and the Solving SIBO Program.

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