Lymphatic absorption of structured glycerolipids containing medium-chain fatty acids and linoleic acid, and their effect on cholesterol absorption in rats

The effects of various structured triglycerides containing medium-chain (caprylic or capric acids) and long-chain (linoleic acid) fatty acids on fatty acid and cholesterol absorption were studied in lymph-cannulated rats. A considerable portion of capric and caprylic acid was absorbed through the lymph duct, although to a lesser extent than was linoleic acid. Capric and linoleic acid located at the 2-position of 2-decanoyl-1,3-dilinoleoyl-glycerol (18:2/10:0/18:2) and 2-linoleoyl-1,3-didecanoyl-glycerol (10:0/18:2/10:0), respectively, tended to be absorbed more efficiently than those located at the 1- and 3-position or those from tricaprin (10:0/10:0/10:0) or trilinolein (18:2/18:2/18:2). A similar trend was observed when the medium-chain fatty acid was caprylic acid instead of capric acid. Caprylic acid absorption from 2-octanoyl-1,3-dilinoleoylglycerol (18:2/8:0/18:2) was significantly greater (p<0.05) than from 2-linoleoyl-1,3-dioctanoyl-glycerol (8:0/18:2/8:0) or tricaprylin (8:0/8:0/8:0). Preferential absorption of caprylic and linoleic acid was not observed when the 1 to 2 and the 2 to 1 mixtures of 8:0/8:0/8:0 and 18:2/18:2/18:2, respectively, were administered. The structured lipids did not affect the lymphatic absorption of cholesterol. The results suggest that structured triglycerides composed of medium-chain fatty acids and linoleic acid may be more useful for the treatment of lipid malabsorption than are mixtures of medium-chain triglyceride (MCT) and long-chain triglycride (LCT).