Lymphatic absorption of seal and fish oils and their effect on lipid metabolism and eicosanoid production in rats

Eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) were distributed mainly in the sn-1 and 3 positions of seal oil triglyceride and in the sn-2 position of fish oil triglyceride. In Expt. 1, the structural distribution of EPA and DHA in lymph triglyceride of rats given seal or fish oils was similar to the distribution in the administered oils. In Expt. 2, seal oil-rich or fish oil-rich fats having constant polyunsaturated/monounsaturated/saturated fatty acids and n-6/n-3 polyunsaturated fatty acids ratios were fed to rats for 3 weeks. Seal oil more effectively reduced plasma and liver triglyceride than fish oil. Ratio of the productions of aortic prostacyclin and platelet thromboxane A₂ stimulated by thrombin was significantly higher in rats fed seal oil than in those fed fish oil. The results suggested that the different intramolecular distribution of EPA and DHA in dietary fat affected lipid metabolism differently in rats.