Soyars K E, Fischer J G
Department of Foods and Nutrition, The University of Georgia, Athens, GA 30602, USA.
J Nutr. 1998 Apr;128(4):764-70. doi: 10.1093/jn/128.4.764.
It has been suggested that high iron stores enhance colon carcinogenesis. The effect of high dietary iron (Fe) on indices of iron, copper (Cu) and manganese (Mn) status, lipid peroxidation using the thiobarbituric acid reactive substances assay, superoxide dismutase, glutathione peroxidase, glutathione transferase and ceruloplasmin activities, cell proliferation and development of preneoplastic lesions known as aberrant 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 (HFe; 450 mg Fe/kg diet) dietary Fe for 2.5 wk, then treated with azoxymethane (AOM; 2 injections, 1 wk apart; total dose 30 mg/kg body weight) or saline (n = 14-15 per group). Dietary treatment continued for another 6 wk after the second AOM dose. At the time of AOM injection, colon Fe concentrations were one- and threefold higher for MHFe and HFe rats, respectively, than for AFe rats. It was proposed that high dietary Fe would adversely affect Cu and Mn status, resulting in impaired antioxidant enzyme activity. However, neither indices of Cu and Mn status nor colonic mucosal antioxidant enzyme activities were affected by dietary Fe except for plasma ceruloplasmin activity, which was slightly lower 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 lipid peroxidation, cell proliferation or ACF development. In conclusion, our findings suggest that dietary Fe concentrations that are approximately 5 and 10 times adequate do not enhance oxidative stress, cell proliferation and ACF development in the colon of rats.
有人提出，高铁储存量会增强结肠癌的发生。采用3×2析因设计，研究了高膳食铁（Fe）对大鼠结肠中铁、铜（Cu）和锰（Mn）状态指标、使用硫代巴比妥酸反应物质分析法测定的脂质过氧化、超氧化物歧化酶、谷胱甘肽过氧化物酶、谷胱甘肽转移酶和铜蓝蛋白活性、细胞增殖以及称为异常隐窝灶（ACF）的癌前病变发展的影响。雄性断乳Sprague-Dawley大鼠分别喂食充足铁（AFe；45毫克铁/千克饲料）、中度高铁（MHFe；225毫克铁/千克饲料）和高铁（HFe；450毫克铁/千克饲料）2.5周，然后用乙氧基甲烷（AOM；注射2次，间隔1周；总剂量30毫克/千克体重）或生理盐水处理（每组n = 14 - 15）。第二次AOM剂量后，饮食处理再持续6周。在注射AOM时，MHFe和HFe大鼠的结肠铁浓度分别比AFe大鼠高1倍和3倍。有人提出，高膳食铁会对铜和锰状态产生不利影响，导致抗氧化酶活性受损。然而，除了血浆铜蓝蛋白活性外，铜和锰状态指标以及结肠黏膜抗氧化酶活性均未受膳食铁的影响，喂食高铁饮食的大鼠血浆铜蓝蛋白活性略低于喂食充足铁饮食的大鼠（P < 0.01）。膳食铁对结肠黏膜脂质过氧化、细胞增殖或ACF发展没有显著影响。总之，我们的研究结果表明，约为充足量5倍和10倍的膳食铁浓度不会增强大鼠结肠中的氧化应激、细胞增殖和ACF发展。
