Supplementation by vitamin D compounds does not affect colonic tumor development in vitamin D sufficient murine models

► The effect of vitamin D compounds on colon tumors has been studied in the Pirc rat and Min mouse. ► Supplementation with 25(OH)D3 neither prevents nor slows the growth of tumors. ► A highly potent analog and a non-calcemic analog of 1,25(OH)2D3 each failed to affect tumor emergence or growth.