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Small Intestinal Bacterial Overgrowth or SIBO

In essence, SIBO is the overgrowth of bacteria in the WRONG LOCATION.  They should be in the large intestine where they ferment food to produce SCFA’s (short chain fatty acids), not in the small intestine.  The small intestine is designed for enzymes and breaking down food into smaller molecules, especially carbohydrates.  How many of you have problems digesting carbohydrates and starches?  We would think many.

Symptoms of SIBO include:



Alternating constipation and diarrhoea

Abdominal cramping

Boating and/or wind

Burping and Acid reflux/GORD

Food sensitivities

Joint pain

Skin rashes

Iron & B12 deficiency

Respiratory symptoms such as asthma

There are many reasons why SIBO started in the first place.  Low stomach acid is certainly one of the first places we look at as this sets of the cascade of digestion problems.

How stomach acid is produced and why suppressing it is not a good idea.

Because it really affects small intestinal function it will disrupts many of the normal functions the small intestine is involved with such as:

  • Breakdown or digestion of monosaccharides and disaccharides (the last part of carbohydrate/starch digestion).
  • Fermentation of these monosacchardies/disaccharides that have not been properly digested resulting in methane or hydrogen sulphate gasses to build up.
  • Methane and hydrogen sulphate gas production that can damage the gut wall especially if butyrate is deficient because fermentation is not happening in the large intestine, but the small intestine, and CBS is upregulated or downregulated.
  • Malabsorption of vitamins and minerals in the small intestine, or amino acids if low stomach acid is involved.
  • Lack of DAO enzymes to break down excessive histamine in foods which can contribute to leaky gut and cause nutrient deficiencies and food intolerance reactions.

So what can cause SIBO?  Apart from the lack of stomach acid production as already mentioned, it can also occur after a bout of gastroenteritis or other infection.  Those consuming high carbohydrate diets (which is about 80% of the Australian population at the moment) or using medications such as antacids or PPI’s (Proton Pump Inhibitors)  will have increased likelihood of developing SIBO as you need proper stomach acid to kill pathogenic bacteria.

Stress!!  This is a big one.  Don’t underestimate the effect stress has on your body.  Stress can interfere with stomach acid production via the HPA (Hypothalamic-Pituitary-Adrenal) axis and really affect stomach acid production and the motility of the intestines via the cholinergic pathway (vagus nerve).  

Sometimes it can be more structural as malformation of the ileocecal valve, surgical intervention causing scarring and adhesions, or abnormal length of the colon or small intestine can all contribute to SIBO.

Often we have to go right back to birth to assess what bacteria colonized the gut first (natural birth vs caesarean birth) and what bacteria was promoted to grow the fastest (breast feeding vs bottle feeding).

Often SIBO itself can cause further damage to the absorptive surfaces of the small intestine and interfere with DAO, SULT and DPPIV enzymes.  This will affect the way you break down gluten, soy, dairy, carbohydrates, sugar, phenols, salicylates and sulfur foods such as garlic, onions, cabbage, broccoli and kale.  These enzymes sit on the villi (finger-like protrusions) on the surface of the small intestine which is why they are called ‘brush border enxymes’.  They have to do that final part of digestion that so many people seem to have problems with.  If they don’t digest properly, symptoms of food intolerances, salicylate intolerances, high-histamine food intolerances, gluten-wheat-soy intolerances all start to develop.  

Read more about SIBO

Contact us for more information or book an appointment with one of our practitioners.  Please note that our practitioners may have different areas of interest and don’t necessarily use the same testing methods.  If you have specific needs or expectations, and are not familiar with our practitioners, we suggest you contact us and we’ll direct your inquiry to the appropriate practitioner(s).

Associated Conditions

Fibromyalgia or Chronic fatigue – usually hydrogen-sulphate dominant

Chronic constipation – usually methane dominant

Irritable Bowel Syndrome (IBS)

Inflammatory Bowel Disease (IBD)

Acid reflux

Coeliac disease

Interstitial cystitis

Restless leg syndrome

Acne rosacea




Chronic prostatitis

Non Alcoholic Steatohepatitis (NASH)

Liver cirrhosis