Effect of age on the modification of rat plasma lipids by fish and soybean oil diets.

The effects of sardine and soybean oils on plasma lipids have been studied in young and aged rats. Plasma cholesterol and bile acids of aged rats fed on a sardine oil diet decreased to a greater degree than those of young rats. Cholesterol, bile acids and phospholipids of the soybean oil diet group decreased only in aged rats. Increases in plasma eicosapentaenoic (sardine) and linoleic (soybean) acid levels of aged rats were observed to be greater than those of young rats. These results indicate that the age enhances the effects of fish and soybean oils on plasma lipids by suppressing their characteristic fatty acid metabolism.