What is SIBO?
Small intestine bacterial overgrowth, or SIBO, is a condition that is characterized by a sudden excess number of bacteria in the small intestine. The small intestine, measuring about 6 to 7 feet in the average human, is located between the stomach and large intestine. Levels of bacteria in this part of the gut are normally low but when it exceeds 5 log colony-forming unit (CFU)/mL then a diagnosis of SIBO can be made.
The overgrowth of bacteria in the small intestine can cause the following gastrointestinal issues:
- Abdominal pain and cramps
- Bloating and gas
- Feeling full
- Sudden weight loss2
SIBO and Probiotics: What Organisms Are in the Small Intestine?
The gut is home to over 400 species of bacteria. One study looked at the microflora from 63 patients with SIBO. These patients had diarrhea, malabsorption and other conditions characteristic of SIBO. Results of the study confirmed concentrations of certain bacteria in 55 of the patients. These bacteria include:
- E coli
What are the best probiotics for SIBO?
SIBO is defined as having excessive amounts of microorganisms in the small intestine. How is it then that taking probiotics, which are microorganisms, be helpful for this condition?
The following clinical studies have found that probiotics are helpful for SIBO when used in conjunction with antibiotics. Probiotics help prevent SIBO from coming back after antibiotic treatment of SIBO.
In one study, researchers evaluated 30 patients suffering from chronic abdominal pain and diarrhea while passing a hydrogen breath test. These patients were randomized into two groups: a control group and a probiotic supplement group. Both groups received initial 3-week aggressive therapies using broad spectrum antibiotics. The probiotic group then received a 15-day maintenance antibiotic therapy using a probiotic with Lactobacillus sporogenes. After a 6-month period, researchers measured patients’ hydrogen breath test results and gastrointestinal symptoms.
Results showed that the probiotic group had a better response based on hydrogen breath test results and clinical symptoms. In patients who received the probiotic, all symptoms of abdominal pain were completely gone while gas, bloating, diarrhea, and other symptoms showed drastic improvement. This suggests that probiotics may be beneficial for SIBO when combined with traditional antibiotic therapy.5
In another study, 40 patients diagnosed with small intestine bacterial overgrowth based on the results of lactulose and glucose breath tests were randomly divided into two groups homogenous for age and gender.
The first group received 400 mg per day of rifaximin (an antibiotic used for SIBO) for seven days followed by Lactobacillus casei for another seven days. The second group was given the same antibiotic and dosage for seven days followed by a short chain fructo-oligosaccharide prebiotic supplement. The patients filled out questionnaires evaluating their own symptoms based on Rome III criteria for irritable bowel syndrome (IBS) and the Bristol scale for stool characteristics. These questionnaires were completed before the study and six months after treatment.
Researchers found that the group treated with antibiotics followed by probiotics had significant improvements in five out of six symptoms. The group treated with antibiotics followed by prebiotics had improvements in four out of six symptoms (there were no improvements in nausea or the number of bowel movements).
Researchers did observe a trend of probiotics being more effective than prebiotics, but the improvements in symptoms was not statistically significant.6
The use probiotics without antibiotics for SIBO has not been established but the use of probiotics after the administration of antibiotics may be helpful for the treatment of SIBO.
Determining the best probiotic supplement for SIBO is difficult and can vary based on your health and specific needs. As mentioned in the above studies, probiotics containing strains of Lactobacilli have been found to be effective, so the best probiotic for SIBO should contain Lactobacilli. However, be careful when using probiotics for SIBO. If you do decide to take SIBO probiotics, make sure that you talk to your doctor and use antibiotics beforehand.
While a variety of bacteria reside throughout the gastrointestinal system, in a healthy human the majority of gut microbes live in the large intestine and not in the large intestine. Microorganisms are generally kept out of the small intestine thanks to:
Gastric acids in the stomach help to break down foods while killing most organisms that are swallowed, preventing them from ever reaching the small intestine. Those with reduced or absent gastric from using antacids or proton-pump inhibitors often have a higher incidence of bacterial colonization in the upper small intestine.
Impaired Peristalsis (Migrating Motor Complexes)
Migrating motor complexes are a distinct form of electromechanical activity. The regular and rhythmic contractions of the gut move food from the stomach through the gut and out the other end. These contractions help keep the small intestine free of excess food particles and bacteria. People with impaired gastric motility, like those with diabetes, are more prone to SIBO.
Impaired Bile Production
Produced in the liver and stored in the gallbladder, bile is a fluid that aids in digestion. Similar to gastric acids, bile has antibacterial properties that may contribute to the regulation of bacteria levels in the small intestine. Those with problems producing or secreting bile may be more susceptible to SIBO.
Your gut microbiome helps keep bad microorganisms from taking over. Probiotics produce bacteriocins and compete against bad microorganisms to prevent their overgrowth.3