Effects of Medium-Chain Triglycerides, Long-Chain Triglycerides, or 2-Monododecanoin on Fatty Acid Composition in the Portal Vein, Intestinal Lymph, and Systemic Circulation in Rats

lipases preferentially hydrolyze the 1 and 3 ester bonds of the triglycerides and also show higher activity for short- and medium-chain fatty acids (MCFA) than for long-chain fatty acids (LCFA), producing 2 free fatty acids and one 2-monoglyceride per triglyceride acted upon.1-4 Therefore, dietary medium-chain triglycerides (MCT) and long-chain triglycerides (LCT) have very different metabolic path-ways in digestion and absorption. MCT are more likely to be degraded into 3 fatty acids and the simple glycerol backbone, or to be absorbed intact, and are also more readily oxidized to carbon dioxide or converted to 2 carbon fragments.1-4 MCFA absorbed from the small intestinal cells are transferred directly into the portal vein for transport to the liver for hepatic metabo-lism. In contrast, LCFA are usually reesterified into LCT from The hydrolysis of dietary triglycerides starts in thestomach by lingual lipase and continues in the duo-denum with gastric and pancreatic lipases. All these Background: Fatty acid absorption patterns can have a major impact on the fatty acid composition in the portal, intestinal lymph, and systemic circulation. This study sought to deter-mine the effects of long-chain triglycerides (LCT), medium-chain triglycerides (MCT), and 2-monododecanoin (2mono) on intestinal fatty acid composition during continuous feeding over a brief period. Methods: The lipid sources were 100 % LCT, 100 % MCT, a 50:50 mixture of LCT and MCT (LCT/MCT), and a 50:50 mixture of LCT and 2mono (LCT/2mono). A total of 27 rats were randomly given 1 of the 4 diets at 200 kcal/kg/d, with 30 % of total calories from lipids over 3 hours. Results: MCT significantly increased each of the medium-chain fatty acids (C6:0, C8:0, and C10:0) as free fatty acids in the portal vein and about 10%/mol of C10:0 as triglycerides in the lymph compared with the other groups. There was significantly less C10:0 in lymphatic triglycerides with LCT/MCT than with MCT, but more than in the LCT and LCT/2mono diets. MCT also significantly increased the contents of C16:0