IRON SUPPLEMENTATION DOES NOT AFFECT CELL-PROLIFERATION OR ABERRANT CRYPT FOCI DEVELOPMENT IN THE COLON OF SPRAGUE-DAWLEY RATS

It has been suggested that high iron stores enhance colon carcinogenes is. The effect of high dietary iron (Fe) on indices of iron, copper (C u) and manganese (Mn) status, lipid peroxidation using the thiobarbitu ric acid reactive substances assay, superoxide dismutase, glutathione peroxidase, glutathione transferase and ceruloplasmin activities, cell proliferation and development of preneoplastic lesions known as aberr ant crypt foci (ACF) in rat colon was examined using a 3 x 2 factorial design. Male weanling Sprague-Dawley rats were fed adequate (AFe; 45 mg Fe/kg diet), moderately high (MHFe; 225 mg Fe/kg diet) and high (HF e; 450 mg Fe/kg diet) dietary Fe for 2.5 wk, then treated with azoxyme thane (AOM; 2 injections, 1 wk apart; total dose 30 mg/kg body weight) or saline (n = 14-15 per group). Dietary treatment continued for anot her 6 wk after the second AOM dose, At the time of AOM injection, colo n Fe concentrations were one-and threefold higher for MHFe and HFe rat s, respectively, than for AFe rats. It was proposed that high dietary Fe would adversely affect Cu and Mn status, resulting in impaired anti oxidant enzyme activity. However, neither indices of Cu and Mn status nor colonic mucosal antioxidant enzyme activities were affected by die tary Fe except for plasma ceruloplasmin activity, which was slightly l ower in rats fed high iron diets than in rats fed adequate iron diets (P < 0.01). Dietary Fe had no significant effect on colonic mucosal li pid peroxidation, cell proliferation or ACF development. In conclusion , our findings suggest that dietary Fe concentrations that are similar to 5 and 10 times adequate do not enhance oxidative stress, cell prol iferation and ACF development in the colon of rats.