Butyrate is a bacterial metabolite of dietary fiber in the colon that has been used to treat inflammatory disease. However, the effect of oral supplementation with butyrate on colitis has not been fully explored. We evaluated the effects of and mechanisms underlying oral supplementation with butyrate on experimental murine colitis. In an in vitro study, we found that LPS induced the secretion of cytokines (i.e., IL-8 in COLO 205; TNF-alpha, IL-6, IL-12, and IL-10 in RAW 264.7; and TNF-alpha, IL-6 and IL-12 in peritoneal macrophages obtained from IL-10-deficient [IL-10(-/-)] mice). Butyrate (100muM and 500muM) inhibited pro-inflammatory cytokine production (i.e., IL-8 in COLO205 and TNF-alpha, IL-6 and IL-12 in macrophages) but promoted anti-inflammatory cytokine (i.e., IL-10) production in RAW264.7 cells. Butyrate attenuated both the LPS-induced degradation/phosphorylation of IkappaBalpha and DNA binding of NF-kappaB and enhanced histone H3 acetylation. To confirm that butyrate played a protective role in colitis, an acute colitis model was induced using dextran sulfate sodium (DSS) and a chronic colitis model was induced in IL-10(-/-) mice. The administration of oral butyrate (100mg/kg) significantly improved histological scores in both colitis models, including the IL-10(-/-) mice. In immunohistochemical staining, IkappaBalpha phosphorylation was attenuated, and histone H3 acetylation was reversed in the treated colons of both colitis models. Our results indicate that oral supplementation with butyrate attenuates experimental murine colitis by blocking NF-kappaB signaling and reverses histone acetylation. These anti-colitic effects of butyrate were IL-10-independent. Butyrate may therefore be a therapeutic agent for colitis.