Radiation colitis is an inflammatory response induced by damage to colonic tissue from radiation therapy that primarily affects patients undergoing abdominal or pelvic radiation treatments. In this study, we designed a selenium-loaded probiotic (EcN-Se@SA) encapsulated in sodium alginate gel for the oral treatment of radiation colitis. Selenium nanoparticles (Se NPs) exhibit antioxidant, anti-inflammatory, ferroptosis, and tissue repair-promoting properties. To enhance the therapeutic efficacy of Se NPs for radiation-induced colitis, we combined Se NPs with