Insufficient dietary vitamin e increases the concentration of 7beta-hydroxycholesterol in tissues of rats fed salmon oil

This study was conducted to determine the interaction between the type of dietary fat (coconut oil or salmon oil) and the vitamin E concentration of the diet [10, 20, 40 or 240 mg alpha-tocopherol equivalents (alpha-toc)/kg] in relation to the concentration of 7beta-hydroxycholesterol (7beta-OH) in liver, plasma, LDL and erythrocytes of rats. In the rats whose diet contained salmon oil, the concentration of 7beta-OH was dependent on the dietary vitamin E concentration. Rats whose diet contained 10 mg alpha-toc/kg had significantly higher concentrations of 7beta-OH in all samples studied than those whose diet contained 20, 40 or 240 mg alpha-toc/kg. Increasing the dietary vitamin E concentration from 40 to 240 mg alpha-toc/kg did not reduce the concentration of 7beta-OH in any samples. In the rats whose diet contained coconut oil, the concentration of 7beta-OH was independent of the dietary vitamin E concentration in all samples. The study shows that insufficient vitamin E in the diet increases the formation of 7beta-OH in rats fed salmon oil, whereas a dietary vitamin E supply in excess of the requirement does not lower 7beta-OH concentrations compared with an adequate vitamin E supply.