The present invention provides compositions comprising β-hydroxybutyrate, cyclic or linear β-hydroxybutyrate oligomers, and/or β-hydroxybutyrate ester derivatives, or pharmaceutically-acceptable salts thereof. In various embodiments, the compositions are encapsulated by nanoparticles, such as nanoparticles comprising, e.g., poly(lactic-co-glycolic acid). In additional embodiments, the invention provides methods of using such compositions to induce intestinal stem cell regeneration and/or treat radiation-induced intestinal damage in a subject.