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SIBO, SIFO, & IMO: Differences & Treatment Strategies

Gut dysbiosis has become a prominent concern, and various small intestinal overgrowths are now being recognized, including hydrogen-dominant SIBO, hydrogen sulfide-dominant SIBO, intestinal methanogen overgrowth (IMO), and small intestinal fungal overgrowth (SIFO). These overgrowths can lead to a host of digestive symptoms and potential nutrient malabsorption.

This article aims to shed light on these conditions, explore their contributing factors, discuss common symptoms, and highlight testing methods for accurate diagnosis. Furthermore, we will delve into treatment options, focusing on general strategies to address SIBO, SIFO, and IMO.

Understanding Small Intestinal Overgrowths:

Small Intestinal Overgrowth occurs when there is an abnormal increase in the number of microbes in the small intestine, disrupting its delicate balance. Unlike the large intestine, which harbors a rich microbial community, the small intestine typically maintains lower bacterial populations. Overgrowth can involve bacteria, fungi, or archaea, leading to a range of gastrointestinal symptoms, such as bloating, gas, diarrhea, constipation, abdominal pain, and cramping.

Factors Predisposing to Small Intestinal Overgrowths:

Several factors can contribute to the development of these overgrowths. Low gastric acid and slow motility are two primary mechanisms that protect the small intestine from overgrowth. When these protective mechanisms fail, SIBO, SIFO, and IMO can arise. Additionally, certain conditions like irritable bowel syndrome, intestinal motility disorders, and chronic pancreatitis increase the risk of small intestinal overgrowths. Prevalence also increases with age and in individuals with lower stomach acid levels or slower gut motility.

Symptoms and Nutrient Malabsorption:

Small intestinal overgrowths can manifest with diverse symptoms, overlapping with other digestive disorders. Common signs include bloating, excessive gas, diarrhea, constipation, abdominal pain, and cramping. Furthermore, malabsorption of nutrients, particularly fat-soluble vitamins (A, D, E, K) and essential minerals (iron, calcium, magnesium), can occur. Vitamin B12 deficiency, resulting from damage to the cobalamin binding sites in the mucosa caused by SIBO, is also common. Lastly, the overutilization of certain B vitamins by bacteria in the small intestine can lead to deficiencies in vitamin B1 and B3.

Testing for Small Intestinal Overgrowths:

To identify and diagnose different overgrowths accurately, various tests are available. Breath tests and stool tests are two primary types of tests used to deduce the type of microbial overgrowth. Breath tests involve drinking a sugar solution and collecting breath samples at specific intervals. The Trio Smart Breath Test assesses small intestinal overgrowth by measuring levels of hydrogen, methane, and hydrogen sulfide after the consumption of lactulose or glucose. Stool tests can provide insights into large intestine activity and may be valuable, especially in diagnosing SIFO. It is important to note, however, that small bowel aspirate and urine organic acid testing can also help in making accurate diagnoses.

Treatment Strategies for SIBO, SIFO, and IMO:

1. SIBO (Small Intestinal Bacterial Overgrowth):

  • Low FODMAP Diet: The Low FODMAP diet involves reducing fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) in the diet. This helps deprive bacteria of their main energy source, limiting their growth and fermentation. It can alleviate symptoms like bloating, gas, and abdominal discomfort. However, prolonged elimination of FODMAPs may disrupt gut bacteria balance, so this diet should not exceed six weeks if not effective.

  • Antimicrobial Therapy: Instead of using antibiotics, some people opt for natural antimicrobial agents to manage SIBO. Herbal extracts like oregano oil, berberine, garlic, and grapefruit seed extract have properties that can control the growth of undesirable bacteria in the small intestine. It is important to remember that, like antibiotics, these antimicrobials can impact the gut microbiota, so their use should be judicious.

  • Probiotics: Probiotics are live microorganisms that have positive effects on gut health. In the context of SIBO, probiotics can help balance the composition of gut bacteria and protect against harmful pathogens. They produce antimicrobial substances that inhibit the growth of undesirable bacteria. However, it's crucial to be cautious when using probiotics for SIBO, as their effects can vary depending on the specific strains used. Some individuals may experience worsened symptoms with certain probiotics, so careful selection is essential.

  • Prokinetics: Prokinetics are agents that increase gut motility, helping move food through the gastrointestinal tract. Medications that act as prokinetic agents are available, but natural options like ginger and peppermint can also possess prokinetic properties. These natural options may be considered as a more sustainable approach to support gastrointestinal function.

  • Elemental Diet: The elemental diet formulation consists of hydrolyzed nutrients, minimizing the need for digestion. It is an intense approach involving 14 days of consuming a blended mixture of amino acids, honey, MCT oil, salt, and water. A multivitamin is also consumed daily. After the elemental diet, a reintroduction and prevention protocol is followed, gradually transitioning to a more normal diet.

2. SIFO (Small Intestinal Fungal Overgrowth):

  • Antifungal Medications: In cases of SIFO, antifungal medications like fluconazole are often prescribed to target fungal overgrowth. Herbal antifungals such as artemisinin, oregano, garlic, and olive leaf extract are also used as alternatives to pharmaceutical medications. Antifungals help reduce fungal colonization and invasive fungal infections.

  • Probiotics: Specific probiotics, such as Saccharomyces boulardii, have been studied and shown to be as effective as nystatin in reducing fungal colonization and preventing invasive fungal infections. These probiotics can help balance the gut microbiota and protect against harmful fungal overgrowth.

  • Low Sugar Anti-Candida Diet: Individuals may choose to embark on a low sugar anti-candida diet, avoiding foods that can promote fungal growth. This dietary approach restricts sugar intake to prevent feeding the fungus and supports the overall management of SIFO.

3. IMO (Intestinal Methanogen Overgrowth) Previously Known as Methane-Dominant SIBO:

  • Antimicrobial Therapy: Similar to SIBO, natural antimicrobial agents like herbal extracts can be used to target methanogen overgrowth in the small intestine. Oregano oil, berberine, garlic, and grapefruit seed extract may be effective in controlling archaea growth.

  • Prokinetics: Since slow gut motility also predisposes individuals to IMO, prokinetics are used to improve gut motility and promote proper food movement. As mentioned earlier, ginger and peppermint are natural options with prokinetic properties.

  • Elemental Diet: As with SIBO, the elemental diet has been used in some cases of IMO to starve the archaea and reduce their overgrowth. Following the diet, a careful reintroduction and prevention protocol is followed to maintain gut health.


Effective treatment of small intestinal overgrowths requires a comprehensive approach tailored to each individual's condition. A combination of dietary adjustments, natural antimicrobials, probiotics, prokinetics, and possibly an elemental diet can help restore gut balance and alleviate symptoms. It is crucial to work closely with a qualified healthcare provider to accurately diagnose the type of overgrowth and design an appropriate treatment plan for optimal results.

1 Comment

Makes sense why we crave things like peppermint with an upset stomach!

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