Protective Effects of Diets Supplemented with Omega-3 Polyunsaturated Fatty Acids and Calcium Against Colorectal Tumor Formation

This study is to evaluate the effect of dietary omega-3 polyunsaturated fatty acid (ω-3 PUFA) and/or calcium supplementation on colon tissue of the carcinogenic N -methyl- N -nitrosurea (NMU)-injected rats and to investigate this effect by the assessment of the oxidative stress. The rats were divided into four groups: those fed with a standard diet, with a diet supplemented by ω-3 PUFA, those fed with a diet with calcium, and those fed with a standard diet with the combination of ω-3 PUFA and calcium. Rats were injected with an intrarectal NMU. After 32 weeks, colon tissue specimens and plasma were taken to histopathologically investigate and analyze tissue superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) activities and erythrocyte MDA levels. The tumor incidences in supplemented-diet groups II and IV were found to be significantly lower when compared with those of the controls ( P