What is SIBO?

SIBO stands for Small Intestinal Bacterial Overgrowth. This condition is becoming ever more prevalent, causing a great deal of digestive discomfort as well as symptoms outside of the gastrointestinal tract. SIBO is now considered to be a common underlying cause of IBS.

We all have some bacteria in the small intestine, but these normally occur at a much lower level than in the large intestine. The bacteria involved in SIBO are not always pathogenic, as you might encounter in a bout of food poisoning, but are just as likely to be commensal or opportunistic bacteria – almost like the right bacteria that are just in the wrong place.

One of the roles of bacteria in the large intestine is to break down foods that we aren’t able to digest by our own enzymes, further up the GI tract. This break down process by bacteria is called fermentation. When this fermentation process happens in the small intestine it can cause a lot of gas and bloating. Most of our food is digested and absorbed in the small intestine by our own range of digestive enzymes, but when excess bacteria are present they interfere with this process and get the opportunity to digest the food before we do with their fermentation activity, depriving us of the nutrients we would normally extract.

The bacteria responsible for SIBO produce methane, hydrogen or hydrogen sulfide gases that are responsible for some of the symptoms of SIBO; for example, gas, bloating, constipation or diarrhoea. Bacteria can also produce chemicals that damage the lining of your small intestine, further inhibiting your ability to absorb nutrients. Once the gut lining has been damaged toxins can leak through and cause problems elsewhere in the body, sometimes leading to Leaky Gut Syndrome, where the intestinal wall is letting large molecules of undigested food matter through into the bloodstream and causing immune system reactions.

Signs and Symptoms of SIBO

  • diarrhea or constipation

  • gas or bloating

  • belching 

  • GERD (Gastro-Esophageal Reflux Disorder – commonly known as heartburn)

  • nausea 

  • food sensitivities 

  • nutrient malabsorption 

  • leaky gut 

  • fatigue 

  • brain fog 

  • anxiety 

  • muscle or joint pains.

Factors that Increase The Risk for SIBO

  • Low digestive secretions (stomach acid, pancreatic enzymes, bile); sometimes also caused by the use of stomach-acid suppressing drugs called PPIs – Proton Pump Inhibitors, like omeprazole (e.g. Prilosec and Losec) and similar drugs used for GERD 

  • Use of Oral Contraceptives

  • Alcohol Consumption

  • obstruction/dysfunction in the GI tract including but not limited to digestive valve malfunction or damage to vagal nerve 

  • food poisoning 

  • stress

  • antibiotic use

  • Ehlers Danlos syndrome or Lyme

  • Poor motility from conditions such as hypothyroidism, brain trauma, damage/impediments to nerves​

How to Diagnose SIBO

SIBO is most commonly assessed via a breath test which measures levels of methane and hydrogen gases and can be easily carried out in your own home. The lactulose breath test is most commonly used, but a test using both lactulose AND glucose would be the gold standard.

If your practitioner is adequately trained in interpreting the breath test they should be able to tell you:

  • which type of SIBO you have: Methane, Hydrogen, or Hydrogen Sulphide (this third type may require stool testing)

  • If the overgrowth is occurring in the small or large intestine

  • Which type of SIBO to tackle first, if multiple types are present