SIBO: causes and treatment

Small intestine bacterial overgrowth, also known as SIBO, is frequently mentioned in the world of holistic medicine. Our opinion is that SIBO is over diagnosed and is in fact a pretty rare condition. For that reason we think an article on the subject could be useful in order to clarify many doubts that arise when it’s diagnosed.

SIBO is defined as an overgrowth of bacteria and/or fungus in the small intestine. In other words, the bowel becomes overcrowded with organisms that shouldn’t be there. Many holistic medicine practitioners use to say that this condition caused diseases such as irritable bowel syndrome or Crohn’s disease.

In a healthy subject, almost all bacteria and fungus live in the large bowel, where regulation of the immune system through T-regulatory cells occurs. In SIBO, however, these bacteria travel to the small intestine and cause digestive distress. Depending on the bacteria that have overgrown, we’ll have trouble with the digestion of specific nutrients. For example, certain strains will cause vitamin B12 and iron deficiencies as they feed on these nutrients. SIBO is characterized by several prolonged and intense digestive symptoms:



-Acid reflux




Diagnosis is made by measuring the production of gas after the ingestion of certain sugars such as lactulose and glucose. This, combined with the presence of two of the symptoms above during at least three months is the best diagnostic criteria. The origin of SIBO is unkown but many theories are considered as possible:

-Low stomach acid

-Altered intestinal motility

-Ileocecal valve failure

-Bacterial dysbiosis after antibiotic overuse

SIBO was only first described less than 30 years ago so we’re still miles away from precise diagnostic methods and treatment. The only test considered somewhat useful nowadays is the hydrogen breath test. The patient fasts the day before the test and in the following morning consumes a certain amount of sugar, which will fuel the bacterial activity. Then the amount of gas produced by the bacteria and therefore expelled is measured. The presence and quantity of hydrogen-producing and methane-producing bacteria is important since the treatment differs depending on which of the two types predominates.

Conventional treatment is based on the use of intestinal antibiotics such as metronidazole and rifaximin combined with diets that avoid all complex sugars. For this purpose several diets are useful: the low starch diet, the FODMAPS diet and the specific carbohydrate diet. There are also several natural compounds that seem to be as effective as antibiotics in the treatment of SIBO:

Monolaurin, found in coconut oil, is a strong natural antibiotic.

-Enteric coated peppermint oil has been found to be more useful than rifaximin.

Allicin, present in garlic extracts, is another natural antibiotic.

Oregano oil is another option but must be consumed with together with other oils.

Pau d’arco, ginger and thyme oil seem to increase the absortion of other antibiotics therefore improving the treatment results.

Natural antibiotics have been found effective and safe in SIBO treatment in several studies such as this one with a combination of compounds and this one with peppermint oil.

Diets alone cannot cure SIBO and antibiotic (either conventional or natural) treatment will be necessary in the vast majority of cases. The type of diets that are usually recommended for SIBO are unhealthy in the long term as the elimination of soluble fiber (rice, sweet potatoes, squash, etc…) reduce the production of short chain fatty acids such as butyrate in the bowel. Remember that starch and soluble fiber are necessary for maintenance of a correct bowel flora.

SIBO treatments usually last two years and should be based on the use of antibiotics and the combination of prebiotics and probiotics adapted to the patient. Furthermore, all external factors that may contribute to the disease such as concomitant drugs and an unhealthy diet need to be adressed and even after doing that symptoms may persist for several months.

In any case, patients shouldn’t diagnose themselves with SIBO and, if any suspicion arises, a gastroenterologist should be consulted for the diagnosis and treatment.

SIBO, as irritable bowel syndrome, comprises many symptoms that may occur in quite a few diseases. Because of that, a SIBO diagnosis should only be made after discarding other conditions. Even when SIBO seems to be the culprit, treatment should be personally adapted to each patient since cases can be very different.

Procedure for the diagnosis of SIBO:

-Discarding other diseases: Crohn’s, ulcerative colitis, microscopic colitis, irritable bowel syndrome or infections.

-Hydrogen breath test.

-See if the results of the test match the patient’s symptoms.

-Antimicrobial therapy with metronidazole, rifaximin or natural antibiotics such as peppermint oil, monolaurin, allicin, oregano oil, thyme oil and pau d’arco. The antibiotic of choice will depend on several factors and will be adapted to each patient.

-During the first months a diet low in complex sugars may be used. There are several options available, in our opinion the low starch diet, FODMAP diet, specific carbohydrate dietand even keto or GAPS are the most useful.

-Supplementation with prebiotics and probiotics will vary in each case.


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