<i>Bacillus Coagulans</i> BC99 Protects Ionizing Radiation‐Induced Intestinal Injury and Modulates Gut Microbiota and Metabolites in Mice

The gastrointestinal tract is highly sensitive to ionizing radiation (IR), which causes radiation-induced intestinal injury (RIII). There are no effective drugs available for RIII in routine clinical treatment, which is a major limiting factor during the process of radiotherapy for pelvic abdominal malignancies. In this study, we aimed to elucidate the potential of probiotic Bacillus coagulans BC99 (B.coagulans BC99) in preventing RIII. C57BL/6J mice were gavage-administered with B.coagulans BC99 for 30 days and then exposed to a single dose of 12 Gy x-ray whole abdominal irradiation (WAI). B.coagulans BC99 treatment could mitigate RIII by preventing weight loss, maintaining the integrity of intestinal structure and barrier, improving inflammatory symptoms, modulating oxidative stress, and regulating the composition of gut microbiota, thereby reestablishing intestinal homeostasis. In addition, the potential radioprotective mechanism of B.coagulans BC99 was closely related to the gut microbiota-derived metabolites. This study offers a novel perspective for advancing probiotic-based treatments for RIII and enhancing strategies for the prevention of RIII.