ABSTRACT
I n t ro d u c t i o n Most edible oils contain diacylglycerol (DAG) as a minor constituent. Although the isoform of DAG that occurs in the process of triacylglycerol (TAG) digestion by lingual or pancreatic lipase is 1,2-or 2,3-DAG, a substantial fraction of DAG in edible oils is converted to 1,3-DAG by acyl migration (1). We reported previously that the serum triglyceride concentration of rats fed DAG oil that is composed mainly of 1,3DAG was significantly lower than that of rats fed common TAG oil of a similar fatty acid composition (2). We also showed that the rate of lymphatic transport of triglyceride as chylomicrons was significantly retarded in rats that had been intragastrically infused with a DAG oil emulsion compared with a TAG oil emulsion (3). We reported recently that the long-term ingestion of dietary DAG oil, in contrast to TAG oil, reduces the accumulation of body fat in humans (4,5). In the digestive tract, 1,3-DAG is hydrolyzed either to 1 (or 3)-monoacylglycerol (MAG) and fatty acids or to glycerol and fatty acids v i a the intermediate 1-MAG (6), whereas TAG is hydrolyzed to 2MAG and fatty acids. On the basis of these results, we hypothesized that the limited availability of 2-MAG for reesterification retards chylomicron-triglyceride transport in rats that have been infused with the DAG oil emulsion.
