Abstract 190: Echium and Borage Oil Are as Atheroprotective as Fish Oil in Mice

Abstract

Background: Diets enriched in long chain (>18 carbon) polyunsaturated fatty acids (PUFAs), such as 20:5 n-3 and 22:6 n-3 in fish oil (FO), are atheroprotective. However, most dietary fats consist of 18 carbon PUFAs that are poorly converted to longer chain PUFAs by the rate limiting enzyme, delta-6 desaturase (D6D). Objective: We investigated whether botanical oils enriched in 18 carbon fatty acids beyond the D6D step in the n-6 (borage oil, BO, 18:3 n-6 enriched) and n-3 (Echium oil, EO,18:4 n-3 enriched) pathway of elongation-desaturation are as atheroprotective as FO and the extent to which these botanical oils would affect oxidized CE species in the aorta. Methods: Female low density lipoprotein knockout (LDLr-/-) mice were fed atherogenic diets containing 0.2% cholesterol and 10% calories as palm oil (PO) with an additional 10% of calories as PO, EO, FO, or BO for 16 weeks. Periodic blood samples were taken for lipid and lipoprotein measurements and aortas were harvested after 16 weeks to measure cholesterol content and oxidized CE species. Results: Compared to the PO group, mice fed BO, EO and FO had significantly lower plasma total and very low density lipoprotein cholesterol concentrations. EO and FO groups also had lower plasma triglyceride concentrations compare to PO and BO fed mice. Compared to the PO group, mice fed BO and EO had significantly reduced aortic CE and free cholesterol, comparable to the FO group. Oxidized CE species were not detected in aortas of any diet group. Conclusion: Botanical oils enriched in 18 carbon n-6 or n-3 fatty acids beyond D6D in the elongation-desaturation pathway are as atheroprotective as FO in LDLr -/- mice. Furthermore, mouse aorta oxidized CE species were undetectable; suggesting this oxidized lipid species has a minimal role in mouse atherosclerosis progression.