Iron salts supplemented in a basal ratio, were fed to young Sprague-Dawley male rats for prolonged periods and the frequency of colonic
adenocarcinomas induced by repeated s.c. injection of
1,2-dimethylhydrazine (
DMH) at unit base doses of 9.0 mg/kg, ascertained and compared with the respective controls. In a series employing
ferric ammonium citrate (0.46% Fe), in addition to
ferrous sulfate (0.11% Fe) and
ferric ammonium sulfate (0.12% Fe),
DMH injection was started on day 15 and the animals necropsied 22 weeks after the last of 23 doses. The general condition was more involved with the 0.46% Fe diet and the total colonic lesion numbers were in the control range. However, the
ferric ammonium sulfate-fed group showed a significant increase in
tumors in the distal colon portion. In the second experiment, 15%
guar gum as such and in admixture with
ferric ammonium sulfate (0.12%) were compared with the respective controls, the first of 20 weekly dosages of
DMH being administered on day 28 of the feeding. At 32 weeks following injection 1, the overall lesion differences were not remarkable, but the
guar gum ratios engendered decreases in the distal colon
tumor frequencies. In general, lesion incidence was extensive, involving 80-100% of the animals per group of the 2 series.
Adenocarcinomas occurred in the small intestine and were more prominent in the control and 15%
guar gum dietary groups but fewer with the
ferric ammonium sulfate supplement.