To Low FODMAP, or Not to Low FODMAP: Dietary Impact on Microbial Imbalances in the Small Intestine

New Research Calls low-FODMAP Diet into Question as a Long-term Solution for SIBO

Forty percent of American adults have a functional GI disorder. SIBO is just one possible chronic GI condition causing their symptoms. And if their symptoms stem from IBS, there’s up to a 78% chance that SIBO plays a role.

Incidence of IBS and SIBO

Growing evidence suggests IBS overlaps considerably with SIBO. In fact, experts believe SIBO is implicated in the vast majority of the estimated 30 million cases of IBS in North America – and that number is climbing! Failure to properly treat SIBO can lead to nutrient malabsorption, weight loss or gain, and systemic inflammation – resulting in a host of downstream complications.  

Conventional treatment for SIBO involves antibiotics to eradicate overgrowth. However, 43% of patients had a SIBO recurrence nine months after completing antibiotic treatment.¹  Focusing solely on antibiotic therapy may not yield the results you and your patient are looking for.  

Antibiotic therapies don’t just address pathogenic bacteria – they induce changes in microbial diversity and reduce commensal bacteria,² inevitably causing dysbiosis. Further, when competing bacteria are diminished, the pendulum can swing from bacterial overgrowth to fungal overgrowth (most commonly Candida). The result? Fungi and yeast bloom across the body, and of particular note, in the small intestine, causing SIFO. 

Low-FODMAP Diet: A Commonly Prescribed Dietary Intervention 

Since the clinical picture of IBS and SIBO (and even SIFO) are comparable, some experts suggest the recommendations for IBS patients can be applied to SIBO patients – although this has yet to be established by research. One current nutritional strategy for managing SIBO includes implementing a low-FODMAP diet and supplementing with prebiotics and/or probiotics.

Reducing or eliminating foods high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) may reduce abdominal pain, bloating, constipation, and diarrhea by depriving small intestinal bacteria of their food source. 

Decreased intestinal osmotic activity and reduced gas production from the bacterial fermentation of unabsorbed, undigested carbohydrates in the colon results in symptomatic relief. However, little is known about the long-term risks of a low-FODMAP diet. 

A narrative literature review published in the journal Nutrients in August 2022 emphasizes the adverse effects of a prolonged low-FODMAP diet, resulting in an unfavorable shift in the microbiota composition and increasing dysbiosis in SIBO patients.³ One of the studies revealed that 42% of IBS patients on a low-FODMAP diet for four weeks scored higher on the dysbiosis index.⁴ This therapeutic diet might temporarily decrease discomfort in patients with GI symptoms. However, long-term adherence to the low-FODMAP diet may result in negative health effects. 

FODMAPs act as prebiotics to feed the microbiome and stimulate the growth of keystone species, including Akkermansia Municiphila, Bifidobacteria, and Faecalibacterium prausnitzii. 

These essential bacteria have a myriad of benefits, including:

• Promoting the production of short-chain fatty acids (SCFA)
• Supporting microbial diversity 
• Strengthening the gut barrier 
• Offering anti-inflammatory properties 

So, one might call the low-FODMAP diet an anti-prebiotic diet because it promotes a reduction in beneficial bacterial species!

As a practitioner, you know that implementing a restrictive diet needs to be done with great care. Restriction can be challenging to sustain and, in some patients, may result in disordered eating, such as orthorexia – when healthy eating becomes obsessive.

Therapeutics for SIBO

When addressing SIBO, apart from identifying risk factors and the underlying cause, therapeutics should involve:

• Antimicrobials to address the overgrowth – promote balance in the gut
• Addressing the oral microbiome – which translocates to the gut   
• Probiotics – Bacillus coagulans, Saccharomyces boulardii, and/or Lactobacillus reuteri
• Mindful eating – the migrating motor complex (MMC) responsible for sweeping food debris and bacteria in the GI tract into the colon is often compromised in individuals who have SIBO
• Prebiotics  –partially hydrolyzed guar gum (PHGG) and/or psyllium husk (Be selective, as some may aggravate symptoms)

While antibiotics are recognized as a first-line treatment for SIBO, they come with some problems. 

• Relapse is common.
• Some patients are resistant to antibiotic therapy.
• They are not selective - wiping out beneficials and creating space for different pathogens to overgrow.
• They are not effective against biofilms - a common cause of refractory illness. This is where botanical formulations shine! 

Botanicals as a Promising Alternative

In a pilot study, participants with hydrogen-dominant SIBO had a 50% reduction in the hydrogen breath test after supplementing with Biocidin® Liquid and GI Detox™+ for an eight-week period. Individuals with methane-dominant SIBO had a 75% decrease in methane-producing bacteria when their protocol included Biocidin® Liquid, Olivirex®, and GI Detox™+. 

In addition to reducing the pathogenic organisms, botanical formulations appear to be selective – resulting in an increase in probiotic abundance in the microbiome.  A 2020 pilot study using Biocidin® Liquid and GI Detox™+ for eight weeks resulted in a 69% increase of probiotic abundance. Notably 73% of the participants had an increase in Akkermansia muciniphila.

Don’t Forget the Mouth! An often overlooked area when addressing SIBO is the oral microbiome. Candida, bacteria, and other microbes are commonly overgrown in the mouth, leading to an overgrowth in the gastrointestinal tract. By balancing the gut microbiome and overlooking the oral microbiome, patients can struggle with recurrent flares. Both should be addressed when treating SIBO.

Final Thoughts

While conventional treatment for SIBO usually involves a low-FODMAP diet and one round – or more – of antibiotics, resolution is often temporary and comes with risks. Attempting a short-term low-FODMAP diet may help reduce symptoms, but it won’t address the root cause of the problem – bacterial overgrowth. 

For a definitive conclusion, more research into this area is required. Until then, it is reasonable to use caution when prescribing the low-FODMAP diet and instead target SIBO with lifestyle, diet – including prebiotics and probiotics, and botanical formulations. This combination may offer the results you and your patient are working toward.

For more information, see the SIBO/SIFO Protocol Sheet

References:

1. Lauritano EC, Gabrielli M, Scarpellini E, Lupascu A, Novi M, Sottili S, Vitale G, Cesario V, Serricchio M, Cammarota G, Gasbarrini G, Gasbarrini A. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. Am J Gastroenterol. 2008 Aug;103(8):2031-5. doi: 10.1111/j.1572-0241.2008.02030.x. PMID: 18802998.  
2. Patangia DV, Anthony Ryan C, Dempsey E, Paul Ross R, Stanton C. Impact of antibiotics on the human microbiome and consequences for host health. Microbiologyopen. 2022 Feb;11(1):e1260. doi: 10.1002/mbo3.1260. PMID: 35212478; PMCID: PMC8756738.
3. Wielgosz-Grochowska JP, Domanski N, Drywień ME. Efficacy of an Irritable Bowel Syndrome Diet in the Treatment of Small Intestinal Bacterial Overgrowth: A Narrative Review. Nutrients. 2022 Aug 17;14(16):3382. doi: 10.3390/nu14163382. PMID: 36014888; PMCID: PMC9412469.
4. Bennet SMP, Böhn L, Störsrud S, Liljebo T, Collin L, Lindfors P, Törnblom H, Öhman L, Simrén M. Multivariate modeling of fecal bacterial profiles of patients with IBS predicts responsiveness to a diet low in FODMAPs. Gut. 2018 May;67(5):872-881. doi: 10.1136/gutjnl-2016-313128. Epub 2017 Apr 17. PMID: 28416515.