Small Intestinal Bacterial, or Fungal, Overgrowth (SIBO or SIFO) also sometimes referred to as Small Bowel Bacterial Overgrowth Syndrome (SBBOS)

Bacteria abound in the intestines with the predominance in the large intestines.

There are ten times as many micro-organisms in the gut as there are cells in the human body! And they have an important job to do in letting us metabolise fatty acids, produce vitamins B and K and far more.However, with SIBO far more bacteria populate the small intestine than normal including those normally restricted to the large intestine.

(Image of Escherichia coli, one of the many species of bacteria present in the human gut, thanks to Wikipedia)

Symptoms of SIBO include those of Irritable Bowel Syndrome: constipation, diarrhoea, flatulence, nausea, bloating, abdominal pains and cramps, tiredness and loss of energy (though it is important to realise these symptoms are also commonly found due to other conditions).

The bacteria may rob our bodies of essential nutrients by feeding on them themselves, particularly iron and B12 vitamins which may render us anaemic.

Causes of overgrowth may not be clear. Some surgical procedures of the intestine and some medical conditions affecting the movement of bacteria down the intestines (the "Migrating Motor Complex") may be to blame.

Another possible cause could be the acid suppressant medication used by acid reflux sufferers. From a meta analyisis published in Clinical Gastroenterology and Hepatology in May 2013, "Proton pump inhibitor use and the risk of small intestinal bacterial overgrowth", the following observation was made, Use of proton pump inhibitors (PPIs) could predispose individuals to small intestinal bacterial overgrowth (SIBO) by altering the intraluminal environment and bacterial flora. There is controversy regarding the risk of SIBO among PPI users because of conflicting results from prior studies." and the following conclusions were reached, "PPI use statistically was associated with SIBO risk, but only when the diagnosis was made by a highly accurate test (duodenal or jejunal aspirate culture). Differences in study results could arise from the use of different tests to diagnose SIBO." [c-viii]

SIBO may be treated with antibiotics but frequently recurs.

There are suggested diets that some sufferers find relief from including Specific Carbohydrate Diet (SCD), the Gut And Psychology Syndrome Diet (GAPS), the Low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) diet, the Cedars-Sinai Diet (CSD) and the FAST TRACT diet. These have not been assessed here as are beyond the scope of this book.