SIBO - Small Intestine Bacterial Overgrowth

Small Intestinal Bacterial Overgrowth (SIBO): Overview & Treatment

What is covered in this article?

  1. Defining small intestinal bacterial overgrowth (SIBO) and its potential causes
  2. Common symptoms
  3. Current functional diagnosis and treatment options
  4. One of the key Chinese herbal formula’s for treating SIBO
  5. Chinese medicine dietary and lifestyle considerations to ease symptoms and prevent recurrences
  6. A look at Betaine Hydrochloride in restoring stomach function and addressing one of the root causes of SIBO

What is Small Intestinal Bacteria Overgrowth?

Small Intestinal Bacterial Overgrowth (SIBO) refers to an imbalance and overgrowth of bacteria in the small intestine, which is marked by non-specific digestive symptoms. Although their are several proposed causes for this condition, current research indicates that dysfunction to the anatomy and motility of the small intestine are the largest risk factors for developing the condition [1]. Other potential causes include chronic use of antacids, also known as proton pump inhibitors (PPI’s), low stomach acid (hypochlorydria) or bile acids, pancreatic enzyme deficiency, dysfunction of the ileocecal valve, and metabolic or systemic conditions such as type 2 diabetes and hypothyroidism [2].

Previous research has been undertaken to investigate the common bacterial strains causing SIBO. One study based on a culture of jejunal aspirates demonstrated Streptococcus and Staphylococcus species, Klebsiella pneumoniae, E. coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Enterococcus faecium were some of the dominant bacteria amongst patients with SIBO [3].

Bacteria causing SIBO

Common symptoms of SIBO

SIBO often presents with a range of non-specific symptoms, including abdominal bloating and distention, gut pains, frequent burping or flatulence, reflux, nausea, changes to bowel habits and stool, weight loss, vitamin B12 deficiency, increased intestinal permeability (‘leaky gut’) and fatigue [4]. However, the two most common symptoms of SIBO are chronic loose stools and abdominal bloating, which is typically worse after consuming a meal containing carbohydrates or high FODMAP foods (more on this later). Ongoing research has also revealed that there is a likely a connection between SIBO and irritable bowel syndrome (IBS), as up to 78% of IBS sufferers may have underlying gastrointestinal dysbiosis and/or SIBO infection [5].

How is SIBO diagnosed?

The clinical ‘gold standard’ for testing SIBO is a small intestinal culture via endoscopy, however this method of testing is typically not used due to the invasiveness and limitations in obtaining an accurate sample. Instead, a 2-3 hour breath test is often the first line of investigation, as its considered simple, straightforward and non-invasive [4].

To perform a SIBO breath test, a patient will consume a small sugar solution, typically lactulose, which is a non-absorbable sugar in humans. Bacteria present in the gastrointestinal tract will metabolise the lactulose, and in turn produce hydrogen and methane gases as a byproduct. A positive SIBO breath test will result in early peaks in breath methane and hydrogen due to an overgrowth of bacteria in the small intestine, which metabolise the lactulose. Conversely, a negative SIBO test will result in a peak in breath hydrogen and methane at around the 2 to 3 hour mark, indicating normal metabolism of the lactulose by bacteria in the large intestine.

SIBO breath test

Functional medicine treatment for SIBO

To treat SIBO, it is vital to address the underlying cause, reduce bacterial overgrowth, and treat potential nutritional deficiencies. Dietary measures are often required for moderate to severe cases, including reducing lactose (a milk sugar) and commencing a low sugar/carbohydrate diet [6]. Among the most commonly utilised dietary interventions for SIBO is the low-FODMAP (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) diet, which restricts many foods and ideally should only be used short-term (see Figure.1 below for examples of low-FODMAP foods).

The core idea of a low-FODMAP diet is to restrict the intake of certain carbohydrates which can be fermented and metabolised by bacteria present in the small intestine, thereby reducing symptoms of gas and bloating [7]. A low-FODMAP diet is also secondarily used to starve the the overgrowth of bacteria, making it easy to reduce their numbers whilst in the ‘active phase’ or antimicrobial part of treatment.

Potential concerns of a Low-FODMAP diet:

Although a low-FODMAP diet is commonly used in the treatment of IBS and SIBO, there are some limitations which should be discussed based on a review paper from 2017 [8].

  1. A low-FODMAP plan has not been adequately tested against other diets, such as a gluten-free diet which is also moderately reduces high FODMAP foods. Therefore other dietary measures could be just as effective but less restrictive. However at this stage, there is currently not enough evidence to support the use of other diets for the treatment of SIBO.
  2. A low-FODMAP diet may increase the rates of eating disorders in certain individuals.
  3. When used long-term, a low-FODMAP diet can lead to several nutritional inadequacies, compounding nutritional deficiencies already present for people with chronic SIBO.
  4. Lastly, many FODMAP foods are metabolised and fermented by the beneficial bacteria present in the large intestine. Therefore, restricting FODMAP foods long-term can lead to a decrease in the numbers of beneficial bacteria, which are essential for modulating the immune system, producing certain vitamins (vitamin B1 and K2), short-chain fatty acids such a butyrate, and preventing overgrowth of harmful bacteria in the gastrointestinal tracts.
Low-FODMAP diet for SIBO

Figure 1: Examples of high-FODMAP foods

With concern to some of these limitations, it is imperative that a low-FODMAP diet is used short-term during the active treatment phase, which is typically between 4-6 weeks for most cases. However, in a clinical setting adjustments to one’s diet is specific and depends on individual circumstances, severity of the condition, other co-morbidities, and medications.

Antibiotic treatment for SIBO:

Antibiotics such as Rifaximin, Tetracycline, Neomycin, Metronidazole and Clindamycin are the most frequently used for gastrointestinal related infections. Among these, Rifaximin appears to be the most safe and effective antibiotic in the treatment of SIBO, with a success rate of around 67.7% according to some studies. However, other studies have indicated varying success rates [9].

Although Rifaximin is a broad-spectrum antibiotic, it is often the preferred antibiotic of choice as it targets both anaerobic and aerobic bacteria. Additionally, Rifaximin has shown minimal absorption into the blood stream, prevents bacterial translocation and adherence to the gastrointestinal tract wall, demonstrates moderate anti-inflammatory effects, and appears to exert minimal damage to the microbiome present in the large intestine [10].

Although Rifaximin is generally considered a safe and well tolerated treatment option, it will only reduce the present bacterial overgrowth in the small intestine and not address the underlying cause or prevent SIBO relapses. In the cases of SIBO relapses, repeated antibiotic use can lead to antibiotic resistant bacterial strains which are becoming an ongoing global health threat. Epidemiological studies have demonstrated a clear link between chronic antibiotic use and the dissemination of antibiotic resistant bacteria, which are an ongoing threat to positive clinical health outcomes. (11)

Antimicrobial herbs:

Previous research has been conducted to assess the efficacy of antimicrobial herbs in the treatment of SIBO. A study in 2017 was performed to investigate the use of herbal antimicrobials against Rifaximin for SIBO. The specific antimicrobial herbs included oregano oil, wormwood and berberine, which is plant constituent found in the Chinese herb Coptis Chinensis. The study revealed that a combination of antimicrobial herbs may be more effective than Rifaximin for the treatment of SIBO. However, there were some limitations to this study such as the timing of the intervention, smaller dose of Rifaximin used, lack of diet control, and the multiplicity of herbs [12]. Regardless of these potential limitations, the study did indicate that these antimicrobial herbs may be an effective treatment for SIBO.

Berberine Complex Panaxea International

Figure 2: A common product used in clinic for gastrointestinal infections, PCOS and diabetes mellitus II.

Key Chinese herbal formula & SIBO

There are several key classical Chinese herbal formulas which can be applied in the treatment of SIBO, dependant on the patient’s symptoms, pulse and tongue diagnosis. However, the formula Ban Xia Xie Xin Tang should take the limelight for its well researched use in several gastrointestinal conditions [13, 14, 15]. Ban Xia Xie Xin Tang predominately treats digestive symptoms, such as diarrhoea or constipation, upper abdominal fullness and bloating which is worse after a meal, reflux, nausea, flatulence and gastrointestinal pains. Sound very similar to how SIBO presents, right?

Ban Xia Xie Xin Tang contains the herbs Huang Lian (Coptis Chinensis) and Huang Qin (Scutellaria baicalensis), both which clear heat and toxicity, eliminate dampness and stop bleeding according to Chinese medicine. Both herbs also contain the active plant constituent berberine, which based on previous research has shown to have antibacterial effects against several bacterial strains, including antibiotic-resistant Methicillin-resistant Staphylococcus aureus (MRSA). Other studies indicate it also improves host immunity to fight infections [16, 17].

Ban Xia Xie Xin Tang formula for gastrointestinal disorders

Figure 3: Herbs contained in Ban Xia Xie Xin Tang

Other herbs contained in Ban Xia Xie Xin Tang include Gan Jiang (Rhizoma Zingiberis/ginger) and Jiang Ban Xia (Rhizoma Pinelliae), which are used in Chinese medicine to harmonise the stomach, resolve phlegm and mucus and alleviate nausea. Research indicates that ginger can increase HCL production, as well as gut motility, gastric emptying time, and relieve digestive symptoms such as nausea or vomiting [18, 19]. Based on this reserach, ginger should be considered when addressing some of the underlying causes of SIBO, such as delayed gastrointestinal tract motility and low stomach acid production.

The last remaining herbs in Ban Xia Xie Xin Tang are Zhi Gan Cao (Radix Glycyrrhizae), Da Zao (fructus jujubae) and Ren Shen (Radix Ginseng). These herbs are used in Chinese medicine to replenishing Qi and Blood, restore Yang to increase energy levels, and relieve heat and toxicity. Research has also demonstrated that Zhi Gao Cao exerts antimicrobial, anti-inflammatory and immunoregulatory effects in the body [20].

Chinese medicine dietary considerations:

Regarding Chinese medicine interventions, it is essential to address the key lifestyle or dietary factors which contribute to the susceptibility to developing SIBO. The following suggestions can be used to assist both the acute and recovery phase of treatment, but please note that these are only general guidelines and often dietary advise is tailored to the individual and their presentation.

  1. Consume only cooked and easy to digest foods and avoid cold or raw foods such as salads, smoothies, juices and ice-cold beverages.
  2. During the initial stages of treatment, avoid the consumption of fruit, wheat-grains and sugary foods as these directly contribute to Dampness and Spleen weakness according to Chinese medicine. Low sugar containing fruits such as blueberries may be tolerated in small quantities for mild and moderate cases.
  3. Avoid consuming fluids 30mins prior and 30mins after a main meal to ensure the digestive fire is strong. If fluids are required to take medications/supplements during a meal, take small slow sips of warm water.
  4. Mix 1 tsp of apple cider vinegar (ACV) with 1 tsp of water (1:1 ratio) and consume this when eating a main meal. ACV helps to stimulate the digestive fire. However, it is best to avoid ACV if you suspect you have histamine intolerance. You can read more about histamine intolerance here. Generally considered a safe alternative to ACV is supplementing Betaine Hydrochloride + pepsin, which aids in stomach acid production and protein digestion (more on this in the next section).
  5. Avoid snacking between main meals, which allows intestinal Qi to move food contents throughout the intestine, preventing food stagnation. This is akin to our modern understanding of the migrating motor complex or intestinal peristalsis, which is a key factor to preventing SIBO.
  6. Take note of any suspected foods which potentially trigger gas, bloating, gut pains, loose stools, and consider eliminating these within the active phase of treatment.
  7. Chew all foods thoroughly and in a relaxed state.

Betaine Hydrochloride for SIBO

As previously stated, hypochlorhydria (low stomach acid) is a known underlying cause for the development of SIBO, especially in aging patient’s or after chronic PPI use. To correct the underproduction of stomach acid, previous research suggests the use of Betaine Hydrochloride (HCL) and pepsin (a protein degrading enzyme) to increase the amount of HCL present in the stomach when digesting food. If there is suspected hypochlorydria, one simple protocol involves taking 1 capsule of Betaine HCL with a meal and slowly increase the dose until the baseline tolerance has been met. When symptoms such as heat, burning or reflux begin to be felt, then the maximum therapeutic dose has been reached. However, if these symptoms are felt after taking only 1 capsule, then this likely indicates ‘normal’ HCL production and no concern of hypochlorydria [19, 21].

A caution: If experiencing any acute flare of gastritis or eosophagitis, then HCL should not be prescribed until these gastrointestinal inflammatory disorders have been adequately treated. This is why its imperative to work with a qualified health professional who can guide and tailor the treatment according to individual needs.

Closing Thoughts:

SIBO is a complex and multifaceted condition which requires tackling diet and lifestyle, and by actively decreasing bacterial overgrowth and removing key drivers. A combination of western functional medicine and Chinese medicine may offer the solution to navigating and treating this difficult condition. If you have been struggling with SIBO or any other niggling digestive disorder, seek the advise of a trusted health professional who can help you get to the bottom of your symptoms and regain a sense of inner health and wellbeing!


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