Understanding SIBO: From Causes and Symptoms to Tests and Therapeutics

A Note from Jocelyn Strand, ND, Biocidin Botanicals Director of Clinical Education:

When I was in Medical School almost 20 years ago, there was no such diagnosis as SIBO or SIFO. In fact, we never even talked about the microbiome or dysbiosis! Our clinical understanding of gut health has evolved over time from defining mechanical function and mucosal integrity to the discovery of the importance of microbial balance. 

Now we understand that not only is the microbiome important, but that it needs to be isolated primarily to the colon, or it will generate what we now know of as SIBO. And while our clinical understanding improves, what stays consistent is the efficacy of plant medicine in helping to establish and maintain healthy balance, wherever microbes are playing a role. 

Registered Dietitian Erika Stowe-Madison, has taken a direct interest in SIBO and SIFO and makes it a point to stay updated on the latest research and clinical developments in the field. She has created the following monograph for clinicians as a resource.

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What is SIBO?

SIBO is an acronym that stands for small intestinal bacterial overgrowth. It is a condition where bacteria that should typically inhabit the colon (large intestine) are present in increased numbers in the small intestine.

What does SIBO look and feel like?

• Gas
• Bloating
• Diarrhea and/or constipation
• Malabsorption
• Anemia
• Weight gain or loss
• Abdominal pain
• Food intolerances
• Systemic inflammation

If these symptoms sound like Irritable Bowel Syndrome (IBS), that’s because 60%–80% of all IBS cases are actually caused by SIBO!

Why does SIBO happen?

Usually, our gut has natural mechanisms (such as hydrochloric acid, motility, and the ileocecal valve) to keep bacteria relatively quarantined in the large intestine so that the small intestine remains comparatively sterile. In SIBO, however, microorganisms from the colon excessively populate the small bowel. Some possible causes may include:¹

• Intestinal infection (parasites or food poisoning)
• Low fiber and high sugar diet
• History of abdominal surgery
• Diabetes (or other conditions that can affect the neurological system)
• Celiac disease
• Intestinal adhesions (or other anatomical differences)
• Chronic antibiotic use or acid-blocking medications

Determining if it’s SIBO  

Diagnosis of SIBO can be a challenge, as standardization and mainstream acceptance are lacking in the medical community. 

What are the testing options?

• Breath Tests. These are the least invasive and most widely available tests for SIBO. Breath tests are now available for all three SIBO varieties. Although research suggests their accuracy as a diagnostic tool is not ideal, prominent clinicians have varying opinions regarding their usefulness.  

• Jejunal Aspirates. Although considered the “gold standard” in the research community, these tests are invasive. (They include biopsies of mucosal juices in the mid-region of the small intestine). They are also expensive and largely unavailable.

Types of SIBO

Currently, three types of SIBO have been identified. While bloating, gas, and abdominal pain are the hallmark SIBO symptoms, each SIBO type has discrete symptoms.

• Hydrogen Dominant: diarrhea or mixed constipation/diarrhea
• Methane Dominant: now referred to as Intestinal Methanogen Overgrowth (IMO) – constipation
• Hydrogen Sulfide: diarrhea, nausea, bladder pain, and gas that smells like sulfur (rotten eggs)⁶

Clinical Pearl:  While each SIBO type has typical presentations, symptoms may also present atypically. Bearing that in mind, taking a breath test may offer greater insight versus diagnosis based on symptoms alone.

Addressing SIBO

To date, addressing SIBO has been largely empirical, as it has not undergone the scrutiny of sponsored clinical trials. As such, there are currently three supported types of therapeutic approaches.⁵

Antibiotics

The mainstay of conventional SIBO treatment is antibiotics. Practitioners are using rifaximin (non-systemic) to treat hydrogen dominant, while metronidazole (systemic) and neomycin are often used for methane dominant. Rifaximin, the most well-studied antibiotic for SIBO, has a breath test resolution rate between 49.5%-70%. While these percentages are reasonably adequate, it is worth mentioning that a one-month supply of this antibiotic costs ~$1,200. Its high price tag is likely due to the FDA, which has only approved its use for hepatic encephalopathy, not SIBO. 

Perhaps the most important question to consider regarding using antibiotics to treat SIBO is, do the benefits outweigh the risks? Evidence has revealed that the impacts of some antibiotics can remain for long periods. As Jackobsson and colleagues found in their study on Short-Term Antibiotic Treatment on the Human Throat and Gut Microbiome, residual effects can sometimes last up to four years post-treatment. Impacts observed are antibiotic resistance and changes to specific members of an individual's microbial community, lasting for extended periods.^{3, 11, 12, 13}

Clinical Pearl: Recurrent or persistent conditions (like SIBO) are often driven by biofilms. Biofilms are communities of microorganisms. They are present in all environments, including the human body. Not all biofilms are harmful; some are even beneficial. However, those biofilms consisting of pathogenic microorganisms can have adverse effects. Pathogenic biofilms have the ability to withstand the presence of high antibiotic concentrations, which can lead to antibiotic resistance.¹⁴

Botanicals

While the research into antimicrobial herbs to treat SIBO is still budding, it offers a promising alternative to costly antibiotics and may be less disruptive to the microbiome. Herbs tested for their antimicrobial effects regarding SIBO include oil of oregano, berberine, wormwood, lemon balm, red thyme, Indian barberry, garlic, black cumin, cloves, cinnamon, thyme, all-spices, bay leaves, mustard, peppermint, and rosemary. 

In one retrospective study, Victor Chedid and colleagues looked at herbal therapies among SIBO patients, comparing their results to those taking rifaximin. They found that 46% of patients normalized their breath test with herbal therapy alone, compared to 34% with rifaximin, demonstrating no statistical difference between therapies. Furthermore, they found that 9% of individuals using rifaximin had side effects, one of which was the acquisition of C. difficile, which was not present in the herbal therapy group.^{5, 11}

Clinical Pearl: Herbs and other plant-derived extracts contain bioactive molecules that have been shown to suppress biofilm formation, leading to their title: anti-biofilm agents.¹⁵

Diet

The Elemental Formula has proven to be an effective SIBO therapy. This fiber-free formula, also referred to as pre-digested, contains nutrients in their simplest form. Patients are told to drink the formula for a minimum of 14 days, and more often 21 days, before retesting. The thought behind this treatment is that it will starve the microorganisms in the distal small intestine (the most problematic site for SIBO) until they die. This method is reported to be ~77% effective; however, it is not typically a one-and-done treatment method. For those who choose this route, it will often need to be revisited (1-2 times annually). This treatment is the most difficult for patients to adhere to and comes with other considerations. Thrush is one concern, and dysmotility is another. Practitioners often recommend concurrent use of antifungals and prokinetics to combat these concerns.⁵

The Low-FODMAP diet has been used to decrease SIBO’s non-specific symptoms (gas, bloating, nausea). Low-FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. Foods that are high in these are often not well-tolerated by those with SIBO or IBS. However, it is highly individual. It is worth mentioning that while this diet has been shown to alleviate common SIBO symptoms, it is not a sole intervention and should not be used long-term as it will lead to nutritional deficiencies.⁵

Nutritional Recommendations

Individuals with SIBO experience inflammation and damage to the brush border in the part of the bowel that normally absorbs nutrients. The resulting malabsorption may lead to steatorrhea, contributing to a deficiency of fat-soluble vitamins A, D, E, and K. Additionally, SIBO patients run the risk of developing a B12 deficiency (leading to neuropathy in some cases), as well as anemia due to B-12, B6, folate or iron deficiency. Fortunately, as Hippocrates said, we can let food be our medicine.

Foods containing glutamine, curcumin, zinc, and omega-3 fatty acids are particularly effective at quenching the intestinal inflammation often present in SIBO. These foods include meat, shellfish, and peanut butter (zinc); bone broth (glutamine); turmeric (curcumin); and salmon (omega-3). Other Low-FODMAP foods replete with nutrients SIBO sufferers are often deficient in are listed below.⁹

• Vitamin A: Eggs, lactose-free milk, carrots, arugula, spinach
• Vitamin D: Lactose-free milk, fatty fish such as salmon and sardines (Sun exposure is also helpful to increase Vitamin D intake.)
• Vitamin E: Sunflower seeds, peanuts, olive oil (garlic-infused olive oil too!)
• Vitamin K: Arugula, spinach, swiss chard
• Vitamin B6: Salmon, chicken, spinach
• Folate: Broccoli, spinach, romaine lettuce, fortified white rice
• Vitamin B-12: Meat, fish, poultry, lactose-free milk
• Iron: Meat, fish, poultry, quinoa, potatoes, spinach

Clinical Pearl: Probiotic supplements and foods are controversial among practitioners. Careful selection of SIBO-safe probiotics (such as Bacillus subtilis, Bacillus clausii, and Bacillus coagulans) is important for individuals with SIBO. Otherwise, it is recommended to wait until after antimicrobial treatment, when they can tolerate FODMAPs better. Additionally, fermented foods and beverages, such as kombucha, are generally not well-tolerated and can exacerbate discomfort, bloating, and other symptoms. Furthermore, some SIBO patients experience constipation and may be tempted to increase their fiber intake. However, fermentable fiber may exacerbate symptoms if added to the diet. Practitioners have used psyllium, a non-fermentable fiber, to help relieve constipation.

For those addressing SIBO nutritionally, these flavor-packed energy balls are simple to make and a great snack when you’re on the go. A SIBO-safe recipe to get you started!

Oat, cranberry, and chocolate chip energy balls¹⁰

Serving size = 1-2 balls 

1 cup rolled oats
1 tbsp chia seeds
1 tbsp flax seeds OR ground flax seeds
1.5 tsp ground cinnamon
1 tsp ground OR fresh-grated ginger
½ cup dried cranberries
1.5 Tbsp maple syrup
½ cup puffed quinoa
½ cup natural creamy peanut butter (OR other nut/seed butter that is free of added sugar, salt, and oil)
2 Tbsp refined coconut oil, separated into 1 tbsp increments 
2 Tbsp mini dark chocolate chips

1. Place oats, spices, flax, and chia into a food processor and process until the mixture is flour-like in consistency.
2. Add cranberries, maple syrup, and puffed quinoa to the food processor, then add ½ cup peanut butter and continue to process until a dough begins to form and stick together. Assess the dough by pinching it to see if it sticks together. If not, add 1 tbsp refined coconut oil. NOTE: Dough may be slightly crumbly after peanut butter is added. This is okay.
3. Add chocolate chips and pulse several times until well distributed through the dough.
4. Using a large spoon, scoop out a spoonful of dough and roll it between your hands into neat balls. Place balls in an airtight container and store them in the fridge.

Notes: 

1. For a nut-free alternative, blend 64g of sunflower seeds into a paste and use in place of peanut butter.
2. Dough may appear crumbly before forming into balls. This is okay – they will still form balls.
3. If you have IBS or SIBO, consider the serving size the maximum amount to eat in one sitting. Consuming more than this serving size may result in GI distress due to exceeding the “safe” concentration of FODMAPs in the cranberries (1 tbsp cranberries is the limit).
4. To reduce sugar content, swap regular dried cranberries with reduced-sugar dried cranberries.

Preparation Time: 20 minutes
Yields: 14-16, 1-inch balls
Equipment: food processor, large spoon, spatula

 

References

1. Dukowicz AC, Lacy BE, Levine GM. Small intestinal bacterial overgrowth: a comprehensive review. Gastroenterol Hepatol (N Y). 2007;3(2):112-22.
2. Takakura W, Pimentel M. Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome - An Update. Front Psychiatry. 2020; 11:664. Published 2020 Jul 10. doi:10.3389/fpsyt.2020.00664< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7366247/.
3. Rao SSC, Bhagatwala J. Small Intestinal Bacterial Overgrowth: Clinical Features and Therapeutic Management. Clin Transl Gastroenterol. 2019;10(10):e00078. doi:10.14309/ctg.0000000000000078 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6884350/.
4. Krajicek, E. J., M.D., & Hansel, Stephanie L,M.D., M.S. (2016). Small intestinal bacterial overgrowth: A primary care review. Mayo Clinic Proceedings, 91(12), 1828-1833. doi:http://dx.doi.org.buproxy.bastyr.edu:2048/10.1016/j.mayocp.2016.07.025 https://www-proquest-com.buproxy.bastyr.edu/docview/1845973699?pq-origsite=360link
5. Ren, X., Di, Z., Zhang, Z., Fu, B., Wang, Y., Huang, C., & Du, Y. (2020). Chinese herbal medicine for the treatment of small intestinal bacterial overgrowth (SIBO): A protocol for systematic review and meta-analysis. Medicine, 99(51), e23737. https://doi.org/10.1097/MD.0000000000023737 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7748159/
6. Ruscio, M. Treating SIBO with a High FODMAP Diet & Higher Carb Intake – How Hydrogen Sulfide SIBO Breaks the Rules with Dr. Nirala Jacobi. October 31, 2018. Accessed on June 5, 2021. https://drruscio.com/hydrogen-sulfide-sibo-treatment/
7. Fitzgerald, K (Host). (November 2020). Dr. Pimentel Presents New Perspectives on SIBO and IBS (Audio Podcast Episode). Soundcloud. https://www.drkarafitzgerald.com/2020/10/01/dr-mark-pimentel-presents-new-perspectives-on-sibo-and-ibs/
8. Xu, F., Li, N., Wang, C. et al. Clinical efficacy of fecal microbiota transplantation for patients with small intestinal bacterial overgrowth: a randomized, placebo-controlled clinic study. BMC Gastroenterol 21, 54 (2021). https://doi.org/10.1186/s12876-021-01630-x
9. Linus Pauling Micronutrient Information Center. Corvallis, OR. https://lpi.oregonstate.edu/mic. Accessed June 3, 2021. 
10. Adapted by Ashley Bent from Monash University FODMAP Diet application on March 9, 2019.
11. Chedid V, Dhalla S, Clarke JO, et al. Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Glob Adv Health Med. 2014;3(3):16-24. doi:10.7453/gahmj.2014.019
12. Jernberg C, Lofmark S, Edlund C, Jansson JK. Long-term impacts of antibiotic exposure on the human intestinal microbiota. Microbiology. 2010;156(Pt 11):3216–23
13. Jakobsson H. E., Jernberg C., Andersson A. F., Sjölund-Karlsson M., Jansson J. K., Engstrand L. 2010; Short-term antibiotic treatment has differing long-term impacts on the human throat and gut microbiome. PLoS ONE 5:e9836
14. Lebeaux D, Ghigo JM, Beloin C. Biofilm-related infections: bridging the gap between clinical management and fundamental aspects of recalcitrance toward antibiotics. Microbiol Mol Biol Rev. 2014;78(3):510-543. doi:10.1128/MMBR.00013-14
15. 15. Lu L, Hu W, Tian Z, et al. Developing natural products as potential anti-biofilm agents. Chin Med. 2019;14:11. Published 2019 Mar 20. doi:10.1186/s13020-019-0232-2