Oxidative stress in mice: effects of dietary corn oil and iron

The aim of this study was to analyze the effect of high dietary Fe on liver antioxidant status in mice fed a corn-oil-enriched diet. Male Balb/c mice were fed for 3 wk with a standard diet enriched with 5% by weight of corn oil with adequate Fe (FCO diet) or supplemented with 1% carbonyl Fe (FCOFe diet). The control group was fed a standard diet. The high-Fe diet induced a twofold increase of hepatic Fe level. However, an increase of thymic Fe level has been induced solely by dietary fat. The hepatic copper (Cu) level slightly decreased in the FCO diet. In the spleen, the high-Fe diet-induced increase of Fe level was negatively correlated with the Cu level. The antioxidant status was influenced by both dietary fat and Fe. Mice fed corn-oil-enriched diets had a higher concentration of thiobarbituric acid-reactive substances (TBARS), with a greater increase in the FCOFe diet. Fatty acid analysis showed decreased n-3 and n-6/n-3 ratio, particularly in the FCOFe diet. Hepatic Cu/Zn superoxide dismutase (CuZn-SOD) activity was decreased in FCO diet, and Fe supplementation caused a further decrease in the enzyme activity. These results suggest that feeding with corn oil-enriched diet increases oxidative damage by decreasing antioxidant enzyme defense. The high-Fe diet additionally affects the antioxidant defense system, further increasing the tissue's susceptibility to lipid peroxidation. Additionally, both corn-oil- and Fe-enriched diets have increased the Cu requirement in mice.