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Small Intestinal Bacterial Overgrowth (SIBO)



Small Intestinal Bacterial Overgrowth (SIBO) occurs when bacteria colonise the small intestine. When we talk about bacteria/probiotics in the gut, we specifically mean the large intestine, not the small intestine (SI). If large numbers of bacteria take up residence in the SI, this can cause discomfort, nutrient malabsorption and eventually chronic health issues.


The most common symptoms of SIBO are bloating without being able to expel the gas (because it is stuck between the stomach and the large intestine), distention in the abdomen after eating a meal, especially a meal that contains fibre-rich foods, abdominal pain, fatigue and possibly nausea. Some patients are more prone to constipation and some to diarrhea - this will depend on the type of bacteria that has moved into the SI. Some patients will experience GERD/reflux/heartburn as well, because the pressure from the trapped gas pushes up on their stomachs causing the hydrochloric acid up the esophagus.


Pateints will also notice that some foods are associated with these symptoms, mostly foods high in fibre such as apples, onions, garlic, some grains, some green leafy vegetables, etc. Foods low in fibre, such as animal meats, tend not to cause any symptoms. Many patients who have been previously diagnosed with IBS actually have SIBO.


So, what's going on here? The bacteria in the SI are feeding off the fibre you ingest. Bacteria, like humans, respirate, and when they do they give off gas - this is the bloating you experience. But why are the bacteria in the wrong place? Most likely it is due to a mechanical or biochemical issue in the gastro-intestinal tract (GIT).


The main biochemical reason would be a reduction of hydrochloric acid in the stomach. Some of this acid reaches the SI and keeps the pH rather acidic. When we get older or if we take drugs to reduce the amount of stomach acid, the pH of the stomach and, therefore, of the SI, decreases and bacteria are able to colonise it.


The main mechanical reason is that the SI is not being cleaned out properly. We have a natual 'sweeping' mechanism in the GIT called the Migrating Motor Complex (MMC). This acts like a broom, pushing the mucous, food particles and other 'gunk' toward the large intestine. When the MMC stops functioning well, the SI can become quite 'dirty' - think of a stagnant pool of water - over time it become swampy, but when the water is running/moving it is naturally cleaned. This is what happens in the SI.


Treatment of SIBO is three-fold: 1) you have to stop feeding the bacteria fibres/roughage/prebiotics, 2) you need to use an anti-microbial treatment to further reduce the number of bacteria residing in the SI, and 3) use prokinetic herbs to get the MMC functioning again.


If you are interested in learning more about SIBO, listen to this podcast with the foremost researcher of SIBO and IBS, Dr. Mark Pimentel, speaking with Dr. Mark Hyman (founder of functional medicine).


If you suspect you may have SIBO, book an appointment to discuss how to treat it naturally with food, herbs and supplements.

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