To investigate the effect of different dietary oils on the main hepatic enzymes involved in metabolism and their impact on oxidative stress status.Twenty-four male Wistar rats were fed for 60 d on the same basal diet plus different lipid sources from commercial oils: soybean (S), olive (O), coconut (C), and grape seed (G). After sacrifice, the liver lipid fatty acid composition, enzymatic and non-enzymatic components of the antioxidant defense system, and the activity of enzymes involved in lipid metabolism were determined. The concentration of Ca 2+ in plasma and liver homogenates was also measured.The diets produced significant changes in the total and polar lipid fatty acid compositions and alterations in key enzyme activities involved in lipid metabolism. The S and G groups showed significantly increased oxidative stress biomarkers. The enzymatic and non-enzymatic components of the antioxidant defense system were increased in the O and C groups. The highest levels of nitrite plus nitrate were observed in the S and G groups compared with the O and C groups in plasma and in liver homogenates. These were directly correlated with the Ca 2+ concentration. The most beneficial effects were obtained with olive oil. However, it is necessary to study in more detail appropriate mixtures of olive and soybean oils to provide an adequate balance between ω-3 and ω-6 fatty acids.Different dietary oils modify the lipid composition of the plasma and liver, local and systemic antioxidant statuses, and the activity of the key enzymes of lipid metabolism. The interrelation between Ca 2+ and nitrite plus nitrate could be the causal factor underlying the observed changes.
