TIME RELATED INCORPORATION OF (N-3) POLYUNSATURATED FATTY-ACIDS FROM SEAL OIL OR FISH OIL INTO RAT-TISSUE PHOSPHOLIPIDS

In fish oil, (n-3) polyunsaturated fatty acids (PUFA) are mainly esterified in the sn-2 position of the triglycerides, whereas in seal oil they are mainly located in the sn-3 position. We have studied whether this difference affects the fatty acid profiles of phosphatidylethanolamine (PE) and phosphatidylinositol (PI) from heart and kidney in a short term feeding experiment. Three groups of rats were fed diets containing 20 wt% fat with 10% linoleic acid, 18:2(n-6). Two of the diets contained approximately 4% (n-3) fatty acids from either salmon oil or seal oil. At days 0, 1, 2, 4, 9, and 17 after the commencement of the dietary treatment with (n-3) PUFA, the fatty acid profiles were determined. Immediately after the start of the feeding period large replacements of (n-6) fatty acids by (n-3) fatty acids were observed. In the heart, arachidonic acid, 20:4(n-6), and docosapentaenoic acid, C22:5(n-6), were rapidly replaced by docosahexaenoic acid, C22:6(n-3), whereas in the kidney, C20:4(n-6) was replaced by both eicosapentaenoic acid, C20:5(n-3), and C22:6(n-3). The structural differences between the dietary triglycerides did not result in any significant differences (P < 0.05) between the two (n-3) PUFA dietary groups in either the incorporation rate of (n-3) fatty acid or the resulting unsaturation indices of the phospholipids.