Effects of dietary fish oil and oxidized cholesterol on the concentration of 7β‐hydroxycholesterol in liver, plasma, low density lipoproteins and erythrocytes of rats at various vitamin E supply

Abstract

AbstractTwo experiments with rats were carried out to investigate the effect of dietary fish oil and oxidized cholesterol on the concentration of 7β‐hydroxycholesterol, an oxysterol of mainly nonenzymatic origin, in liver, plasma, low density lipoproteins and erythrocytes of rats at different vitamin E supply. In Experiment 1, four groups of rats received diets with coconut oil or salmon oil (100 g/kg diet) and vitamin E concentrations of 40 or 240 mg α‐tocopherol equivalents/kg. In Experiment 2, eight groups of rats received diets supplemented with pure or oxidized cholesterol (5 g/kg), coconut oil or salmon oil (100 g/kg diet) and vitamin E concentrations of 40 or 240 mg α‐tocopherol equivalents/ kg. Rats fed the salmon oil diets had significantly higher concentrations of 7β‐hydroxycholesterol in liver, plasma, low density lipoproteins and erythrocytes than rats fed coconut oil diets. Rats fed the diets supplemented with oxidized cholesterol had significantly higher concentrations of 7β‐hydroxycholesterol in all the samples analyzed than rats fed pure cholesterol. Increasing the dietary vitamin E concentration from 40 to 240 mg α‐tocopherol equivalents/kg diet reduced the concentration of 7β‐hydroxycholesterol in plasma; the concentrations of 7β‐hydroxycholesterol in liver, low density lipoproteins and erythrocytes were not influenced by the dietary vitamin E concentration. The study suggests that diets with fish oil or oxidized cholesterol are critical with respect to the formation of 7β‐hydroxycholesterol.