LYMPHATIC ABSORPTION OF N-3 POLYUNSATURATED FATTY-ACIDS FROM MARINE OILS WITH DIFFERENT INTRAMOLECULAR FATTY-ACID DISTRIBUTIONS

Male Wistar rats were given 0.5 ml of either fish oil or seal oil intr agastrically. The intramolecular fatty acid distributions of the triac ylglycerols administered were determined by non-specific Grignard degr adation followed by isolation and analysis of the 2-mono-acylglycerols . The n - 3 polyunsaturated fatty acids (PUFAs), especially eicosapent aenoic acid (20:5(n - 3)) and docosahexaenoic acid (22:6(n - 3)), were located in outer positions (sn-1/3) in the seal oil triacylglycerols whereas the sn-2 position of fish oil triacylglycerols was enriched in 20:5(n - 3) and 22:6(n - 3). The mesenteric lymph was collected over the following 24 h and the absorption patterns of n - 3 PUFAs were det ermined. In the lymph, the n - 3 fatty acids characteristic of the mar ine oils rapidly increased both with regard to mole percentage and tra nsport (mu g/min). There were, however, no overall significant differe nces in the absorption patterns over a 24 h period. The ratio between mole percentage in the oil and mole percentage in the lymph calculated at the steady-state period was significantly greater for both 20:5(n - 3) and 22:6(n - 3) following fish oil administration compared with s eal oil. Initially, the recovery of it - 3 PUFAs as a percentage of th e total amount transported over the experimental period was higher fol lowing injection of fish oil than seal oil but seal oil resulted in gr eater recovery in the last two fractions at 8 and 24 h post injection, respectively. This indicated that n - 3 PUFAs from fish oil may have been better absorbed in the initial period of digestion but overall th e structure of dietary triacylglycerols had negligible effects on the assimilation of n - 3 PUFAs when these were administered as native mar ine oils.