Dietary medium-chain triacylglycerol prevents the postprandial rise of plasma triacylglycerols but induces hypercholesterolemia in primary hypertriglyceridemic subjects

Background: Previous studies showed divergent results concerning the influence of medium-chain triacylglycerol (MCT) on lipoprotein metabolism. Objective: The objective of this study was to compare the effects of MCT and corn oil on plasma lipids in primary hypertriglyceridemic patients. Design: Ten subjects ate different proportions of corn oil and MCT for 12 wk. The subjects first ate a low-fat diet for 2 wk and during the next 4 wk, corn oil was added as the sole source of fat. Thereafter, for 2-wk periods, the subjects were sequentially fed corn oil and MCT mixed in the following proportions: 3:1, 1:1, and 0:1. Fasting plasma total cholesterol, triacylglycerol, and HDL-cholesterol concentrations were measured at the end of each period. At the end of the 100%-corn oil and of the 100%-MCT periods, subjects were fed a rest meal containing the respective oil (40 g fat/m(2) body surface area) and total cholesterol and triacylglycerols were measured at 2-h intervals over 8 h; fasting lipoprotein composition was also measured. Results: Compared with corn oil, MCT was associated with a higher mean (+/-SD) fasting total cholesterol concentration (6.39 +/- 1.14 compared with 5.51 +/- 0.98 mmol/L, respectively; P < 0.05); non-HDL-cholesterol concentrations were also higher with MCT (5.36 +/- 1.11 mmol/L) than with corn oil (4.51 +/- 0.92 mmol/L; P < 0.005). In response to the liquid test meal, plasma total cholesterol did not change with either diet but triacylglycerols increased with the 100%-corn oil diet. Conclusions: MCT prevents the risk of pancreatitis due to postprandial hypertriglyceridemia but has the inconvenience of raising total cholesterol concentrations in primary hypertriglyceridemic subjects.