The balance of the gut microbiota is essential for digestive health and, more generally, for the well-being of the body. In this context, SIBO (Small Intestinal Bacterial Overgrowth) is an increasingly common condition that affects many people. In this article, we will delve into what SIBO is, its causes, symptoms, and how probiotics can play a crucial role in its treatment.

1. What is SIBO?
2. Causes of SIBO
3. Symptoms of SIBO
4. Classification of SIBO:
5. Treatment of SIBO
6. How do probiotics help with SIBO?
7. Conclusion

What is SIBO?

SIBO, which stands for Small Intestinal Bacterial Overgrowth, is defined as the presence of an excessive number of bacteria in the small intestine, leading to the appearance of gastrointestinal symptoms, typically bloating, abdominal distension, diarrhea, abdominal pain or discomfort, fatigue, and weakness.

Under normal conditions, the bacterial concentration and composition throughout the digestive tract are distinct, with the large intestine being home to trillions of bacteria, while in the small intestine, these concentrations can decrease to about 10³ (thousands) of bacteria in the duodenum.

Although bacteria are essential for proper digestion and overall health, when their quantity increases abnormally in this area of the intestine, it can affect the proper absorption of nutrients, leading to various digestive issues.

However, several factors can disrupt this balance, allowing certain bacteria to proliferate and cause bacterial overgrowth, known as SIBO.

Causes of SIBO

There are several factors that can trigger the development of SIBO, among which the following stand out:

Biological Factors: Females have a higher prevalence of SIBO, and it mainly occurs between the ages of 30 and 50.

Alterations in Intestinal Motility: The intestine has mechanisms that prevent bacteria from colonizing the small intestine. If this function is compromised (for example, due to irritable bowel syndrome or prolonged use of opioids), bacteria may proliferate.

Enzymatic or Gastric Acid Deficiencies: Gastric acid and digestive enzymes are key to controlling the number of bacteria in the small intestine. A decrease in these elements (as occurs in hypochlorhydria or pancreatic insufficiency) can promote bacterial overgrowth.

Anatomical Alterations: Abnormalities in the gastrointestinal tract can create a favorable environment for SIBO. Blind loop syndrome is an example, occurring when a section of the small intestine does not move properly, facilitating excessive bacterial growth. This can result from previous surgeries, certain health conditions, or the use of specific medications.

Prolonged Use of Antibiotics, Opioids, and Other Drugs: Although necessary to treat infections, antibiotics can also disrupt the gut flora, eliminating beneficial bacteria and allowing harmful bacteria to grow uncontrollably. On the other hand, medications like antacids can alter the pH of the microbiota, promoting bacterial overgrowth.

Symptoms of SIBO

The excessive growth of bacteria in the small intestine causes these bacteria to ferment carbohydrates that have not been fully digested, producing gases such as hydrogen and methane. This fermentation not only increases the amount of gas but also interferes with the proper absorption of nutrients, which can increase intestinal permeability and cause symptoms like diarrhea. The symptoms of SIBO can vary from person to person, but the most common include:

• Abdominal distension and gas.
• Abdominal pain or digestive discomfort.
• Diarrhea or constipation.
• Nutritional malabsorption, which can lead to weight loss and nutritional deficiencies.
• Nausea.
• Loss of appetite.
• An uncomfortable feeling of fullness after eating.
• Persistent fatigue.
• Symptoms similar to irritable bowel syndrome (IBS).

These symptoms alone do not confirm a diagnosis of SIBO but may lead us to suspect it.

Classification of SIBO:

• Hydrogen SIBO: Occurs when there is excessive bacterial proliferation. People with this type of SIBO tend to have more diarrhea and rarely experience constipation.
• Methane SIBO (IMO): Occurs when there is an overgrowth of methanogenic archaea and is more associated with constipation.

According to the European Guidelines 2022, it is recommended to use hydrogen and methane breath tests to diagnose SIBO in patients presenting with bloating, abdominal pain, and gas, once other conditions have been ruled out. Although there is no absolute consensus on the interpretation of these tests, they are especially suggested for patients with predisposing factors.

Treatment of SIBO

The treatment of SIBO varies according to the severity of the case and the underlying conditions of each person. It should focus on identifying and correcting (when possible) the underlying causes, correcting nutritional deficiencies, and administering antibiotics.

• Antibiotics: The initial therapy consists of specific antibiotics to eradicate bacterial overgrowth.
• Diet: In patients with SIBO, adjusting the diet is key to alleviating symptoms such as excessive gas production. A low-fiber and low-fermentable sugar diet is recommended during treatment and for up to 8 weeks afterward. It is essential to always consult a professional for proper implementation and follow-up.
• Probiotics: These are live microorganisms currently used as restoratives of the microbiota during and after antibiotic treatment.

How do probiotics help with SIBO?

Probiotics are beneficial bacteria that, when consumed in adequate amounts, can help balance the gut microbiota. In the case of SIBO, several studies have demonstrated that probiotics are effective in reducing the bacterial load in patients with SIBO and alleviating their symptoms, as well as in preventing this condition.

Probiotics may help improve digestive health through the following actions:

• Nutrient Competition: Probiotics introduce beneficial bacteria that compete with harmful bacteria for resources in the intestine, limiting their proliferation and colonizing the gut.
• Production of Antimicrobial Substances: Some probiotic strains produce compounds that inhibit the growth of pathogenic bacteria.
• Strengthening the Intestinal Barrier: Probiotics enhance the function of the intestinal barrier, reducing permeability and preventing toxins and harmful bacteria from entering the body.
• Modulating the Immune System: They also boost the immune system, helping control inflammation and maintain an adequate immune response in the intestine.

Conclusion

SIBO is a condition that can cause debilitating symptoms if not treated appropriately. If you experience symptoms of SIBO or suspect you might have this disorder, it is important to consult a healthcare professional for a proper diagnosis and a personalized treatment plan.

Source

Mayo Clinic. (s.f.). Sobrecrecimiento bacteriano en el intestino delgado (SIBO): Síntomas y causas. Recuperado de https://www.mayoclinic.org/es/diseases-conditions/small-intestinal-bacterial-overgrowth/symptoms-causes/syc-20370168

Sociedad Española de Médicos de Atención Primaria (SEMERGEN). (2023, 28 de septiembre). SIBO: Una enfermedad emergente a tener en cuenta. Recuperado de https://semergen.es/?seccion=sociedad&subSeccion=detalleNoticia&idN=1300

Chong, C. Y. L., & Riordan, S. M. (2020). Small Intestinal Bacterial Overgrowth: Comprehensive Review of Diagnosis, Prevention, and Treatment Methods. Recuperado de https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386065/