Summer 2023 When SIBO hit Social Media
In recent times, SIBO (Small Intestinal Bacterial Overgrowth) has found its way from medical journals to trending social media topics. With its symptoms echoing those of the more common IBS (Irritable Bowel Syndrome), the condition has garnered attention from not just the medical community but also from a broader audience. Interestingly, social media influencers, even those without backgrounds in health or fitness, have been vocal about their experiences, leading to a wave of self-diagnoses predominantly among young adults, teens, and particularly among young females and girls. This article delves into the intricate relationship between SIBO and IBS, the advancements in diagnostic techniques, and the increasing importance of understanding the role of the gut microbiome in overall health.
IBS is a complex broad syndrome
Irritable bowel syndrome (IBS) is a functional bowel disorder produced by recurrent abdominal pain at least once a week in the last three months. It is associated with changes in stool form or stool frequency . Symptoms must arise at least six months before diagnosis. Bloating, constipation, diarrhoea, incontinence, and psychological disturbances are some of the various comorbidities experienced by these patients.
IBS has been associated with stress and anxiety. The brain-gut axis is fundamental in understanding IBS . As a result, many treatments were focus on antidepressants and neurobehavioral intervention . Apart from these different pathophysiological mechanisms had been proposed to explain de IBS symptoms as visceral hyperalgesia, intestinal permeability, immune activation, altered gastrointestinal motility, autoimmunity, and alteration of the gut microbiome .
IBS and microbiome disbyosis: SIBO
The gut microbiome has received significant interest over the last years. Abundant literature has shown a direct relationship between IBS symptoms and disorders of the gut microbiota. One manifestation of this dysbiosis associated with IBS is the small intestinal bacterial overgrowth [SIBO].
The Gold standard for diagnosing SIBO is the presence of ≥ 103 colony-forming units per millilitre (CFU/mL) of jejunal aspirate by culture [4, 5]. However, aspiration is invasive and expensive and requires a skilled gastroenterologist.
Breath Test: Diagnosing SIBO
The breath test is a simplified way to measure SIBO. This study is based on the measurement of gases produced by bacterial fermentation and exhaled on the breath. Hydrogen (H2) and methane (CH4) are an example of them [6-8]. To stimulate bacterial fermentation, we use different types of carbohydrates such as glucose and lactulose. Glucose is a monosaccharide easily absorbed in the proximal small intestine. In contrast, lactulose is a disaccharide that has limited absorbability since it is not digested by host enzymes. . The SIBO symptoms including bloating, abdominal pain, nausea, constipation, and diarrhea, are very similar to the IBS ones.
A positive H2 breath test is diagnostic of SIBO, which has been associated with diarrhea predominant IBS (IBS-D) and IBS with mixed bowel habits (IBS-M) . A positive CH4 breath test shows methanogen overgrowth, associated with constipation-predominant IBS (IBS-C) [5, 11, 12].
The relationship between SIBO and IBS was described in a meta-analysis. 25 case-control studies were included, involving 3.192 IBS subjects and 3.320 controls. The prevalence of SIBO in IBS was 31.0% (95% CI 29.4–32.6) with an OR of 3.7 (95% CI 2.3–6.0, p = 0.001) compared to controls .
Previous studies have shown that infectious gastroenteritis [14, 15] are associated with the development of IBS, which have been termed post-infectious IBS (PI-IBS). This is another evidence of the relationship between IBS and the gut microbiota.
Infectious diarrhoea is known to cause intestinal permeability [16,17], and a similar phenomenon is seen in patients with IBS, especially in patients with stress . This is thought to be partially mediated through bacterial effects on tight junctions . The mechanisms how intestinal permeability persists after the acute infection, can be explained by the dysbiosis of the gut microbiome.
IBS-SIBO associated to low microbiome diversity
A decline in the gut's microbial biodiversity can set off a chain reaction of health issues. Without a balanced representation of bacterial species, certain strains might proliferate unchecked, potentially leading to disorders like SIBO. It's like removing a predator from an ecosystem and seeing an explosion in the population of its prey, which can have cascading effects on the environment.
One pivotal study, as reported by the Javier Santos Group in Barcelona, illuminated this connection. Their findings showed a discernible decrease in butyrate-producing bacterial families in subjects diagnosed with IBS-D . When the populations of these butyrate-producing bacteria dwindle, the gut may become more susceptible to inflammation, increased permeability, and the consequent manifestation of IBS symptoms. This critical insight underscores the importance of maintaining a rich and varied gut microbiome to preempt or mitigate digestive disorders.
Different treatments for SIBO and IBS are target in the microbiome. The use of a non-absorbable oral antibiotic, rifaximin, is the one with the highest level of success. A meta-analysis that evaluated normalization of a breath test in response to antibiotics for SIBO found that rifaximin was the most common used. A metanalysis by Shah et al. found that antibiotics relieve symptoms in 81.6% of patients. Only five studies reported eradication of SIBO, and 93% of patients with a glucose breath test achieved normalization, while 71.4% of patients diagnosed via small bowel aspirate culture reached normalization . Furthermore, treatment with specific antibiotics results in decreased CH4 levels correlated with constipation improvements [21,22]. Of note, while neomycin and rifaximin can each reduce constipation in IBS-C, using a combination of both appears to be most effective .
Probiotics for IBS
Probiotics have also been evaluated in the treatment of IBS. A systemic review by Ford et al.  found that certain combinations of probiotics may help IBS. However, there was significant heterogeneity between the studies. Interpretation of probiotic studies' metanalyses is difficult since different strains are studied in different combinations assessing various endpoints. Many studies also have small sample sizes, making it hard to generalize the results.
Hydrogen Sulfide as a new marker for SIBO
The exhaled gas hydrogen sulfide [H2S] could be another potential marker of bacterial overgrowth. H2S appears to be implicated in multiple gastrointestinal disorders with pro- and anti-inflammatory properties . Singer-Englar et al. described an association between diarrhea and exhaled H2S levels . This could be a factor implicated in patients with IBS-D.
In today's age of digital information, SIBO has found a spotlight on social media, particularly with influencers sharing their personal narratives. However, it's imperative to tread with caution. The intricacies between SIBO and IBS aren't straightforward, and the symptoms of both can easily be conflated. It's vital not to confuse dysbiosis with a mere growth in the number of CFUs. The presence or abundance of specific microbial strains or taxa does not directly equate to the manifestation of symptoms.
Furthermore, while breath tests are gaining traction as a diagnostic tool, their relationship with the overall bacterial abundance, as measured by 16S rRNA sequencing, remains to be definitively established. Self-diagnosis, especially based on popular narratives, can lead to misinterpretations. Always seek expert medical advice before drawing conclusions about one's gut health. It's essential to separate trending online topics from genuine medical conditions, ensuring that our understanding is rooted in science and expert guidance.;
Because of its therapeutic potential, more research on IBS and SIBO is necessary.