Fig. 4.
Vitamin D deficiency did not increase colonic tumorigenesis in either strain. (A) In the colon of the F344-ApcPirc/+ rat, tumor multiplicities were reduced in animals given a diet devoid in vitamin D (P<0.001); reduced dietary calcium alone also significantly reduced tumor number (P<0.0003). (B) In the colon of the (ACIxF344)F1-ApcPirc/+ rat, there was no effect of vitamin D depletion alone on tumor multiplicity; however, reduction of dietary calcium alone (P=0.03) or in combination with vitamin D deficiency (P<0.005) reduced colonic tumor number. (C) For the small intestine, tumor count in both strains was significantly reduced when low dietary calcium was combined with vitamin D deficiency (P<0.03). By contrast, in the small intestine of the (ACIxF344)F1-ApcPirc/+ rat, tumor multiplicity was increased in rats given a diet absent in vitamin D but normal in calcium (P=0.0001) or vice versa (P=0.02). Each individual point represents data from a single animal. Open circles represent females, while closed circles represent males; all data were blocked by sex and then analyzed jointly. Data were analyzed using a two-tailed Wilcoxon test. All P-values shown have been Bonferroni corrected for multiple testing against a single control group.