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WorldWhat is SIBO, a stomach disorder where there is excess hydrogen in...

What is SIBO, a stomach disorder where there is excess hydrogen in the small intestine?

If you are a regular user of social networks, you have surely heard of the SIBO. Hardly anyone knows her, this intestinal disorder This summer it has become on everyone’s lips, especially young people and teenagers. Many influencers from Instagram and TikTok have shared that they suffered their efects.

The story that repeats itself is the following: a person suffers from digestions heavy, bloating and gas, heartburn, frequent diarrhea.

They give him a simple breath test and tell him that he releases much more hydrogen than normal, due to an overgrowth of bacteria in the small intestine. They prescribe antibiotics.

As a consequence alters entire gut microbiota and recommend that you take probiotics to replenish it.

Perhaps, incidentally, they suggest you do a complete analysis of the intestinal microbiota using a stool sample.

He gets bored of taking probiotics, so they design a “personalized” diet for him. In the end, after several hundred (or thousands) of euros spent, you feel a little better… or not.


What is SIBO and what does it mean?

SIBO is not the name of a bacteria, it is the acronym of Small Intestinal Bacterial Overgrowth (bacterial overgrowth in the small intestine). We call intestinal microbiota to the set of all microorganisms (bacteria, archaea, viruses, fungi and protozoa) that the digestive system houses. It is made up of hundreds, probably thousands, of different species.

In reality, we are a complex ecosystem in balance with millions of interactions between these microbes and our cells. The microbiota supports the healthy functioning of our digestive, immune, endocrine and nervous systems. It produces vitamins, short chain fatty acids, amino acids, neurotransmitters, hormones and many other compounds.

When this balance is altered, due to changes in the composition or number of microorganisms – known as dysbiosis – inflammatory bowel diseases, irritable bowel syndrome or metabolic ailments such as diabetes, obesity and allergies can develop.

But not everything is SIBO. Other types of disorders in the intestinal microbiota: LIBO (bacterial overgrowth in the large intestine), SIFO (fungal overgrowth in the small intestine) and IMO (intestinal methanogen overgrowth).

Too many bacteria in the small intestine

SIBO consists of the presence of colon-specific bacteria in the small intestine in quantities greater than 103 CFU/mL (Colony Forming Units per milliliter).

This involves a change in the balance of individual microbiota species in the small intestine and causes gastrointestinal symptoms. SIBO patients produce excess hydrogen due to fermentation of consumed carbohydrates.

Characteristic bacteria of such overgrowth include Streptococcus, Staphylococcus, Bacteroids and Lactobacillus. There is also usually an increase in the number of microorganisms of the genera Escherichia, Klebsiella and Proteus.

What are the symptoms of SIBO?

As for the symptoms, SIBO usually manifests with abdominal pain, bloating, gas, diarrhea, and irregular bowel movements. These problems can lead to malabsorption, resulting in nutritional deficiencies, anemia, or hypoproteinemia (decreased serum protein concentration).

Furthermore, the accumulation of microorganisms can generate an increase in some bacterial components (such as lipopolysaccharide), which stimulate an inflammatory response and They generate chronic inflammation.

He diagnosis It is performed by aspirating the contents of the jejunum (through endoscopy) and culturing the sample in the laboratory. A concentration greater than 103 CFU/mL in said culture would indicate the presence of SIBO. One of the limitations is that there is still no consensus on what the normal microbiota is in the small intestine.

Due to the invasive nature of this test, indirect breath tests are also used. They consist of measuring the amount of hydrogen and methane that is exhaled after drinking a mixture of water and glucose or lactulose. These types of sugars are They tend to be absorbed and degraded in the large intestine and not in the small intestine.

An increase of more than 20 ppm (parts per million) in hydrogen concentration compared to baseline is also used synonymously with a diagnosis of SIBO. However, this test can give false negatives and false positives.

Is SIBO overdiagnosed?

SIBO often accompanies to diseases of the digestive system and other conditions. Bacterial overgrowth is more common in people who suffer from irritable colon, Crohn’s disease and other inflammatory bowel diseases. It has also been linked to celiac disease, fistulas, strictures, surgical procedures and obesity.

The prevalence is significantly higher among type 1 and type 2 diabetic patients than in the general population.

In addition, the coexistence of SIBO in disease has been identified non-alcoholic fatty liver disease, cirrhosis, chronic pancreatitis, cystic fibrosis, heart failure, hypothyroidism, Parkinson’s disease, depression, systemic sclerosis and chronic kidney failure.

Additionally, irregularities in the structure and function of the intestinal wall, low pressure of the ileocecal valve, excessive concentrations of some compounds, the presence of proinflammatory cytokines, and increased gastric pH can cause the disorder.

In all of these cases, there is an unresolved question: is it the overgrowth of bacteria in the small intestine that causes these diseases or is it these ailments that generate SIBO?

Changing our microbiota is much more difficult than we think

Several strategies have been described to combat SIBO. Antibiotics are widely prescribed, although it is an empirical treatment, since it starts before having information on the microorganisms involved. It is, therefore, a probability treatment. The evidence supporting its use is scarce and it may have other unwanted effects on the intestinal microbiota, favor the development of resistance or infection by Clostridioides difficile.

A temporary beneficial effect has been suggested by reducing fermentable foods in the diet and avoiding products rich in fiber, polyols, sweeteners and prebiotics. This is what they call diets low in FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols).

They are based on temporarily reduce some foods (sugars, starches and fiber) that are poorly assimilated in the small intestine, absorb a lot of water – which alters peristaltic movements – and They ferment quickly in the colon, producing a lot of gases.

There is very little quality research on the effect of probiotics on the microbiota of the small intestine and, specifically, for the treatment of SIBO. The situation is similar with fecal microbiota transplantation: there is insufficient evidence to justify its effectiveness.

It must also be taken into account that a person can test positive for SIBO and be perfectly healthy, without symptoms. All of these treatments do not “cure” SIBO, they can only temporarily relieve symptoms.. SIBO is not a disease, it is a symptom. To eradicate it we would have to go to the causes, and the increase in the number of bacteria is probably a side effect of other diseases that must be treated.

What to do with SIBO?

Although there is an extensive literature on SIBO and other intestinal dysbiosis, its quality is generally limited. Despite recent interest in the gut microbiome and its disorders, more clinical research is needed to determine the pathophysiology, identify effective treatments and prevent microbiota overgrowth in the small and large intestine.

It is not only necessary to know who is there (metagenomics) but also to know what it does and what functions it has (metatranscriptomics and metaproteomics).

Future research may allow us to use specific changes in the composition and diversity of the gut microbiota as biomarkers of specific health or diseases. At the moment, the most urgent thing is, perhaps, to agree on protocols. And if in doubt, you should always go to the doctor and not self-diagnose or self-medicate.

*To read the note on the official site, click click here.

*Written by Ignacio López-Goñi, Member of the SEM (Spanish Society of Microbiology) and Professor of Microbiology, University of Navarra.

*The Conversation is an independent, nonprofit source of news, analysis and commentary from academic experts.

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