Letzte Aktualisierung am 9. September 2024 von Dr. Michael Zechmann-Khreis
A food intolerance such as lactose or fructose intolerance is not always the reason for digestive problems. In addition to many other factors, it can also be a so-called small bowel dysbiosis (SIBO).
Small intestinal mal-colonization occurs in about 10-20% of the population, so it is not uncommon. This mal-colonization is often the result of untreated or undetected food intolerances, but can also be caused by other diseases or circumstances, such as Crohn’s disease, short bowel syndrome or advanced age.
Bacteria in the gut
Bacteria live not only in our large intestine, but in the entire digestive tract. Depending on the section, different types of bacteria – and we are talking about thousands of different species – are found. At the beginning of the digestive tract, bacteria of the Streptococcus and Lactobacillus genus are more common, while in the large intestine, for example, Clostridia or Bifidobacteria are found.
Bacteria usually live in colonies, i.e. they do not travel individually but occur in clusters. While there are tens of thousands of such bacterial colonies in the stomach and at the beginning of the small intestine, there are several billion in the large intestine. This microbiome (formerly known as “intestinal flora“) is a very important factor in digestion. The bacteria help us to break down food, defend us against pathogens or produce vitamins for us. Just a few years ago, it was assumed that the intestinal flora was “there”, but that it was not very important. Science is slowly beginning to understand the relevance of the microbiome. Microbiome research is a young discipline and is still in its infancy; many new findings can be expected in the coming years.
Bacteria in the wrong section of the intestine cause discomfort
Carbohydrates are absorbed in the small intestine. Everything that is not processed in the small intestine ends up in the large intestine. These two sections of the intestine are separated from each other by the so-called ileocecal valve. If this valve does not close properly or is pushed open by increased flatulence, bacteria from the large intestine can migrate into the small intestine and begin to digest carbohydrates there. This is called “small intestine bacterial overgrowth syndrome” and is abbreviated to“DDFB” or “SIBO” in accordance with the term “small intestine bacterial overgrowth syndrome”. The typical symptoms are flatulence, diarrhea, frequent urge to defecate and defecation, pain and, of course, long-term deficiency symptoms. Symptoms as a result of DDFB usually occur relatively soon after eating, as these bacteria live very far forward in the intestine, i.e. at the beginning of the digestive system.
Symptoms of small intestine colonization
The symptoms are flatulence, diarrhea, frequent urge to defecate and defecation, pain and, of course, long-term deficiency symptoms. The symptoms of small intestinal colonization usually appear relatively soon after eating, as these bacteria live very far forward in the intestine, i.e. at the beginning of the digestive system. The symptoms usually occur 20-30 minutes after eating.
Diagnosis and treatment of small bowel malabsorption
Small intestinal colonization is very easy to diagnose by means of an H2 breath test and can be treated effectively with appropriate antibiotics. For the H2 breath test, glucose or lactulose is used as a test substance if there is a suspicion of small intestinal colonization, but DDFB can also be detected during the fructose H2 test. However, the test interpretations are then different.
For lactulose: Test with 10g lactulose. If the value after 90 minutes has already risen by more than 20 ppm or is higher than the values after 120 or 180 minutes, a small intestinal overgrowth can be assumed.
For glucose: The test is performed with 50g glucose. An increase of more than 20 ppm from the initial value is generally considered a positive finding. Glucose is absorbed very quickly and often does not even reach the posterior sections of the small intestine, which is why the lactulose test should be preferred for the diagnosis of small intestinal colonization.
A fructose breath test (tested with 25g fructose), which is carried out if fructose intolerance is suspected, can also provide information. It is important to blow every 10-15 minutes for the first hour and then approx. every 30 minutes. If the measurement curve shows two extreme values, once after approx. 30 minutes and then again after approx. 110 minutes, you must assume a DDFB and a fructose intolerance. If there is only the first extreme value, you only have a DDFB, if there is only the second extreme value, you have no DDFB, but a fructose intolerance.
Is an intestinal flora analysis useful?
Not really. Home tests only reveal which bacterial genera (but not the diagnostically relevant species or subspecies!) are present in the intestine, especially in the rectum. They cannot make any statement about the different intestinal sections and their colonization.
Figuratively speaking: Imagine you are driving through a tunnel in a convertible. At three points in the tunnel, either red, blue or green sand trickles from the ceiling. So when the car drives out of the tunnel, it has red, blue and green sand in the driver’s compartment. The airstream naturally swirls the sand around and blows some of it out of the car. Based on the sand mixture (or a small sample of the sand mixture), it is impossible to say where in the tunnel which sand trickled from the ceiling and how much. Let’s say you have a lot more green sand in the car. This could mean that the green sand trickles down at the end, but it could also mean that it trickled down in enormous quantities at the beginning.
If you imagine our intestines as a tunnel and the bacteria as colorful sand, a home test cannot show how many bacteria of which genus are located where in the intestine.
Treatment of small bowel colonization
Treatment is uncomplicated and is carried out using antibiotics and intestinal flora supplements ( no intestinal flora analysis is necessary for their selection). Of course, it is also important to treat or eliminate the cause of the small intestine colonization. This is because different underlying diseases naturally require different treatment methods.
Sources
- Zechmann, M, Masterman, G., “First aid after diagnosis”, 2017, Berenkamp-Verlag; 5th edition
- World J Gastroenterol. 2014 Mar 14;20(10):2482-91. doi: 10.3748/wjg.v20.i10.2482 / Irritable bowel syndrome and small intestinal bacterial overgrowth: meaningful association or unnecessary hype.
- Uday C. Ghoshal, Ratnakar Shukla, and Ujjala Ghoshal / Gut Liver. 2017 Mar; 11(2): 196-208. Published online 2017 Mar 15. doi: 10.5009/gnl16126 / PMCID: PMC5347643PMID: 28274108, Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy
- Ghoshal UC, Srivastava D, Ghoshal U, Misra A. / Eur J Gastroenterol Hepatol. 2014 Jul;26(7):753-60. Breath tests in the diagnosis of small intestinal bacterial overgrowth in patients with irritable bowel syndrome in comparison with quantitative upper gut aspirate culture.
