SIBO, what is it and how to test for it 

SIBO test NZ

You’re suffering from digestive issues, and you heard about SIBO and SIBO test?

Here an article to understand what SIBO is and if SIBO testing is valid and required.

What is SIBO

SIBO stands for Small Intestinal Bacterial Overgrowth, referring to bacterial proliferation in the small intestine. It is normal (and needed) to have bacteria in our gut, but most of them should be in the large intestine, and much less in the small intestine.

Indeed, there are between 10,000 to 10 million bacteria/mL* in the small intestine. This may seem like a lot, but it’s just a drop in the bucket when you consider that there are 10 to 10,000 billion/mL* microbes in the large intestine!

Intestinal Methanogen Overgrowth (IMO) describes the proliferation of archaea and can extend throughout the entire digestive tract. It accounts for approximately 30% of microbial overgrowths (Banaszak et al., 2023). Archaea use hydrogen produced from carbohydrate proliferation to produce methane. Methanobrevibacter smithii is the dominant microorganism in cases of IMO (Banaszak et al., 2023).

SIBO and IMO are not induced by pathogenic bacteria. It is the excess of microbe that leads to numerous unpleasant symptoms and can also cause medium to long-term complications.

This is crucial because if you do have SIBO/IMO the goal won’t be to eradicate bacteria but to restore a balanced microbiome.

Why is SIBO problematic? 

When bacteria proliferate a bit higher in the digestive tract in the small intestine, troubles can appear (Sorathia & Rivas, 2021).

Most bacteria feed on carbohydrates (= sugars). This induces fermentation. Fermentation is responsible for gas production. In excess, gas cause bloating and abdominal distension (the famous “pregnant belly”).

The small intestine is where our food is broken down and absorbed. If bacteria are not pushed away from the small intestine, they will colonize as they can find plenty of food there!

The bacteria established in the small intestine will produce their own waste products, which will attack the mucosal villi and create (or worsen) intestinal hyperpermeability.

Intestinal hyperpermeability triggers an inflammatory immune response, mainly due to lipopolysaccharides (LPS), molecules found on the membrane of some bacteria species.

These endotoxins are pro-inflammatory and further damage the intestinal mucosa and disrupt our immune system.

If inflammation becomes chronic, it will have significant and detrimental consequences on the body.

Why does SIBO occur?

The cause of SIBO is multifactorial (= multiple causes)(Banaszak et al., 2023) and may be associated with other disorders/pathologies such as (Bures et al., 2010; Salem & Roland, 2014; Rao & Bhagatwala, 2019; Pimentel et al., 2020).

  • Gastroparesis
  • Diverticulitis
  • Crohn Disease
  • Endometriosis
  • Chirurgie (e.g bypass)
  • Hypochloridia (lack of stomach acid)
  • Bile insufficiency
  • Intestinal dysmotility linked with lifestyle, drugs or secondary to bacterial infection 
  • NASH
  • Autoimmune diseases: coeliac disease, IBD, ankylosing spondylitis (Garcia et al., 2019), systemic sclerosis (Marie et al., 2009; Parodi et al., 2008), Hashimoto’s thyroiditis (Lauritano et al., 2007; Patil, 2014)
  • IBD
  • Endometriosis
  • Obesity
  • Diabetes
  • Depression

SIBO is reported to be present in 4 to 78% of patients with IBS, and eradication of SIBO is often associated with improvement in IBS symptoms (Rao & Bhagatwala, 2019).

Post-infectious SIBO

The most common cause of SIBO is food poisoning by E. coli, Campylobacter jejuni, Salmonella, etc.. (Xiao et al., 2021). These bacteria’s, in addition to making us sick, produce a toxin: cytolethal distending toxin (CBT-B).

During food poisoning, or a simple gastroenteritis, our bodies produce antibodies that attack the bacteria and their toxins.

In general, we have a good bout of diarrhoea and/or vomiting for a few hours – or days for the unluckiest, and once the antibodies have done their job and the danger is averted, they “disappear” from circulation.

However, in 10% of cases, these antibodies are a bit confused and attack vinculin, a protein that plays a major role in the proper functioning of the migrating motor complex (you know, our intestinal broom).

This vinculin (protein) is molecularly similar to CBT-B (Morales et al., 2019). They are like twins in a way.

By destroying vinculin, the nerves of the MMC are damaged. The MMC can no longer perform its defense and sweeping role. The “cleaning” does not occur properly, and the bacteria remaining in the small intestine proliferate.

So you may not remember, but the cause of your SIBO may have been the dodgy steak you ate a few months ago!

To help you understand, imagine a river. If there is a current, there is little chance that you will see algae on the surface. However, if the water stagnates, you can observe (and even smell) the development of microorganisms. Well, it might not be a nice picture, but it’s kind of what can happen in your gut.

SIBO symptoms 

SIBO symptoms are common to other digestive disorders such as coeliac disease, lactose intolerance, and irritable bowel syndrome (Bures et al., 2010). Symptoms include:

  • Diarrhoea, steatorrhea (fatty stools)
  • Abdominal pain, gas in excess, bloating and abdominal distension rapidly after eating
  • Acid reflux, dyspepsia, nausea
  • Food intolerance (feeling that you can’t digest anything anymore)
  • Loss of appetite
  • Digestive symptoms develop 2 to 6 months after
    • gastroenteritis
    • taking PPIs
    • opioids
    • abdominal surgery,
    • prolonged antibiotic use
  • Digestive symptoms improve with antibiotic treatment
  • Digestive symptoms worsen after taking probiotics
  • Anxiety, depression, fatigue, brain fog (Rao et al., 2018)
  • Fibers worsen constipation
  • Deficiency in certain nutrients such as B12 (conversely, B12 levels can be abnormally high due to B12 production by certain bacteria)

SIBO and IMO manifest with similar symptoms but have differences. For example, individuals with IMO are less likely to develop a vitamin B12 deficiency (Madigan et al., 2022). Constipated individuals are more likely to have IMO (Madigan et al., 2022), while those with SIBO typically have diarrhea.

You may also present symptoms suggestive of histamine intolerance, which is secondary to SIBO (Schnedl & Enko, 2021).

How to diagnose SIBO – SIBO test

SIBO can induce deficiencies may include fat-soluble vitamins (A,D, or E) and vitamin B12 (Salem & Roland, 2014), magnesium, zinc, selenium, and essential fatty acids. A blood test can be performed but can’t be used as a diagnosis tool.

Aspiration of jejunal fluid for culture is the gold standard but is invasive and costly and is never used outside of studies.

Therefore, breath tests with glucose or lactulose measuring hydrogen and methane are currently the commonly used diagnostic methods (Banaszak et al., 2023).

A SIBO kit : the aim is to expire in the tube linked to a little bag every 20 minutes for 3 hours.

Glucose and lactulose breath tests involve blowing into a small bag after a 24 to 48-hour preparation. Then, the person drinks a sugary solution (either 75 g of glucose or 10 g of lactulose) and blows into a small bag every 20 minutes for 3 hours to track the sugar’s journey through the digestive tract.

Three gases (hydrogen, methane, and CO2) are measured using a Quintron machine

Where to perform SIBO test

In NZ, few labs propose the SIBO breath test kit. You can either go to the lab or do it at home and send back the kit.

Preparation before performing the test is crucial. Probiotics or antibiotics should not be taken up to 4 weeks before the test.

Once you’ve done the test, it is necessary to get an interpretation by a health professional trained to do so.

SIBO/IMO treatment will be different according to your situation and your choices.

SIBO test in NZ
Here an exemple of a SIBO breath test done in NZ.

Take away

  • SIBO/IMO is a proliferation of bacteria or archaea in the small intestine.
  • Symptoms are similar to IBS.
  •  A breath test where the amount of methane, hydrogen are measured is the main SIBO diagnostic method.
  • SIBO/IMO treatment will consist of eliminating microorganisms in excess, supporting digestion, and restoring good digestive health. Diet will play a supporting role. The chosen dietary regimen will need to be individualized.

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  • Banaszak, M., Górna, I., Woźniak, D., Przysławski, J., & Drzymała-Czyż, S. (2023). Association between Gut Dysbiosis and the Occurrence of SIBO, LIBO, SIFO and IMO. Microorganisms, 11(3), 573.
  • Bures, J., Cyrany, J., Kohoutova, D., Förstl, M., Rejchrt, S., Kvetina, J., Vorisek, V., & Kopacova, M. (2010). Small intestinal bacterial overgrowth syndrome. World journal of gastroenterology: WJG, 16(24), 2978.
  • Madigan, K. E., Bundy, R., & Weinberg, R. B. (2022). Distinctive clinical correlates of small intestinal bacterial overgrowth with methanogens. Clinical gastroenterology and hepatology, 20(7), 1598-1605. e1592.
  • Pimentel, M., Saad, R. J., Long, M. D., & Rao, S. S. (2020). ACG clinical guideline: small intestinal bacterial overgrowth. Official journal of the American College of Gastroenterology| ACG, 115(2), 165-178.
  • ao, S. S., & Bhagatwala, J. (2019). Small intestinal bacterial overgrowth: clinical features and therapeutic management. Clinical and Translational Gastroenterology, 10(10).
  • Rao, S. S., Rehman, A., Yu, S., & De Andino, N. M. (2018). Brain fogginess, gas and bloating: a link between SIBO, probiotics and metabolic acidosis. Clinical and Translational Gastroenterology, 9(6).
  • Salem, A., & Roland, B. (2014). Small intestinal bacterial overgrowth (SIBO). J Gastroint Dig Syst, 4(225), 2.
  • Sorathia, S. J., & Rivas, J. M. (2021). Small intestinal bacterial overgrowth. In StatPearls [Internet]. StatPearls Publishing.
  • Xiao, Z. X., Miller, J. S., & Zheng, S. G. (2021). An updated advance of autoantibodies in autoimmune diseases. Autoimmunity Reviews, 20(2), 102743.
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