Small intestinal bacterial overgrowth (SIBO) is an increasingly recognized condition that influences immune responses. It may be linked to atopic disorders such as bronchial asthma (BA), food allergies (FA), chronic spontaneous urticaria (CSU), and mast cell activation syndrome (MCAS). The aim of our study was to perform a structured literature search to assess the possible correlation between SIBO and the presentation of atopic disorders. The prevalence of SIBO was highest in patients with BA (60–100%) and FA (50–87.5%), followed by MCAS (30.9%) and CSU (27.9%). The diagnosis of SIBO was based on lactulose or glucose breath tests. SIBO exacerbated symptoms of atopic diseases, and treating it within BA and MCAS improved the symptoms, in contrast to CSU. The present evidence suggests a possible crosslink between SIBO and atopic manifestations. Bacterial overgrowth appears to trigger the Th2 immune response via the mucosal pathway and low-grade endotoxemia. These result in the increased synthesis of interleukins involved in allergic reactions (IL-4, IL-5, IL-13). Further studies are essential to confirm the clinical significance of this association. The “gut–allergy axis” may offer new therapeutic options and possibly improve quality of life in patients with atopy.
Terlecki et al. (Sun,) studied this question.