The incorporation of n-3 polyunsaturated fatty acids into plasma lipid and lipoprotein fractions in the postprandial phase in healthy volunteers.

OBJECTIVE: To examine the movement of long-chain polyunsaturated n-3 fatty acids across plasma lipoprotein fractions in the postprandial phase. DESIGN: Eight healthy volunteers ingested a test meal (% energy: protein 11, carbohydrate 16, fat 73) after an overnight fast where fish oil provided the sole fat source. Blood samples were taken at baseline and at hourly intervals thereafter for 12 h. Blood lipoprotein fractions were separated and analysed for triacylglycerol fatty acid compositions. These were also determined in non-esterified fatty acid and phospholipid fractions. RESULTS: All n-3 polyunsaturated fatty acids accumulated in all plasma lipoprotein fractions and in non-esterified fatty acids. The ratios of concentrations of docosahexaenoic acid (DHA) to eicosahexaenoic acid (EHA) were higher in chylomicrons (1.4 +/- 0.4) than in very low density lipoproteins (0.9 +/- 0.5) and particularly higher than in the non-esterified fatty acid fractions (0.8 +/- 0.4). The level of eicosapentaenoic acid (EPA) rose significantly in plasma phospholipids while that of docosahexaenoic acid (DHA) did not. CONCLUSIONS: All n-3 polyunsaturated fatty acids are rapidly incorporated into all plasma lipid fractions with the exception of uptake of DHA into plasma phospholipids. There is a clear tendency for EPA and DHA to partition differently into the different plasma lipid fractions.