Lipids and oil are very important nutrients to keep the human health. In addition to this function, lipid is more efective energy source than carbohydrate and protein. One gram of lipid can produce 9 kkal whereas carbohydrate and protein only can deliver 4 kkal/ gram. But, lipids are also involved in mayor health problems. One of them is hypertriglyceridemia. Hypertriglyceridemia in a fasting state is an independent risk factor for coronary artery disease.
Edible oils contain diacylglycerol, which consist two fatty acids that are bound by ester to a glycerol molecule. In animal and humans, incerase in serum triacylglycerol and remant like particle cholesterol concentrations, an index of postpandrial hyperlipidemia and a risk factor for arteriosclerosis, were significantly lower after diacylglycerol-enriched oil than after ingestion of conventional dietary triacylglycerol oil with a fatty acid composition similar to that of diacylglycerol oil. Triacylglycerol is a kind of lpid consist three fatty acids that are bound by ester to a glycerol. Therefore, diacylglycerol oil appears to be effective for preventing pospandrial hyperlipidemia.
This matter is evidenced by the study of Dr. Kazuichi Tomonobu from Kao Corporation, Japan. He examined the effect of ingestion between diacylglycerol oil and triacylglycerol oil to 43 Japanese subjects, 36 men and 7 postmenopausal women, who have passed the screening visit. He used diacylglycerol oil that was prepared by using soybean oil and rapeseed oil while triacylglycerol oil with similar fatty acid composition was prepared by mixing rapeseed oil, high-linoleic safflower oil and perilla oil. And after processing, was added to the test meal. The meal comprised a sandwich, shrimp salad, consomme sup and barley tea.
Subjects were randomized to one of two groups: one group ingested the diacylglycerol meal, and the other group ingested the triacylglycerol meal for the first measurement. In a second measurement, after 2 week washout period, meals were switched between groups. Subjects were instructed to maintain a consistent energy intake and activity level during the test period and to record their meal contents for 7 day before the first and second measurements in a specified dietary diary.
Subjects entered the test room at 9:00 AM on the morning of the test day. After collection of a fasting blood sample (0 h), each subject ingested the test meal within 15 min. Blood was collected at 2, 3, 4, and 6 h after ingestion of test meals. Subjects rested in a sitting position and drank only water during the test.
He found that postpandrial increases in serum triacylglycerol, remnant like particle cholesterol and chylomicron-triacylglycerol levels were significantly lower after ingestion of diacylglycerol oil than after ingestion of triacylglycerol oil in a typical meal. These effect were more evident in subjects with high fasting serum triacylglycerol level.
High fasting serum triacylglycerol levels are generally thought to be due to the increased production and secretion of triacylglycerol-rich lipoprotein or impaired catabolism. If fasting serum triacylglycerol levels are high, the clearance rate of chylomicron that is newely secreted in to the blood might be low due to competition for lipoprotein lipase, resulting in postpandrial hypertriglyceridemia. In the Dr Tomonobu’s study, subjects with high fasting serum triacylglycerol levels had lower increase serum triacylglycerol level after diacylglycerol oil consumption than after triacylglycerol oil consumption.
The metabolic characteristic of diacylglycerol in the digestive tract might be one reason for smaller increase in postpandrial triacylglycerol levels after ingestion of diacylglycerol oil than after ingestion of triacyglycerol oil as a part of meal. Triacylglycerol in the diet is selectively hydrolized in the digestive tract by pancreatic lipase, resulting in the production of 2-monoacylglycerol and free fatty acids. These digestion products are absorbed by small intestinenal epithelial cells, resythesized to triacylglycerol, and released in the form of chylomicron-triacylglycerol into the circulation. In contrast, diacylglycerol oil, might be hydrolized to 1-monoacylglycerol and free fatty acids or to glycerol and free fatty acids. 1-monoacylglycerol is less likely than 2-monoacylglycerol to form chylomicron-triaclyglycerol.
In conclusion, diacylglycerol oil when ingested in a typical meal, suppresses the postpandrial increase in serum levels of triacylglycerol and remnant like particle cholesterol compared with triacylglycerol oil. This effect of diacylglycerol oil might be useful for the prevention of pospandrial hyperlipidemia and other life-style related disease.
A resume completed by Wahyu D. Saputra from the Journal of Nutrition, “ Dietary diacylglycerol in a typical meal suppresses postprandial increases in serum lipid levels compared with dietary triacylglycerol “ ; Kazuichi Tomonobu et. al